

Die vorliegende Übersetzung wurde maschinell erstellt. Im Falle eines Konflikts oder eines Widerspruchs zwischen dieser übersetzten Fassung und der englischen Fassung (einschließlich infolge von Verzögerungen bei der Übersetzung) ist die englische Fassung maßgeblich.

# Amazon QLDB Java-Anleitung
<a name="getting-started.java.tutorial"></a>

**Wichtig**  
Hinweis zum Ende des Supports: Bestandskunden können Amazon QLDB bis zum Ende des Supports am 31.07.2025 nutzen. Weitere Informationen finden Sie unter [Migrieren eines Amazon QLDB-Ledgers zu Amazon](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/) Aurora PostgreSQL.

In dieser Implementierung der Tutorial-Beispielanwendung verwenden Sie den Amazon QLDB-Treiber mit dem, um ein QLDB-Ledger AWS SDK für Java zu erstellen und es mit Beispieldaten zu füllen.

Während Sie dieses Tutorial durcharbeiten, können Sie sich auf die API-Referenz für [AWS SDK für Java Verwaltungs-API-Operationen](https://docs.aws.amazon.com/sdk-for-java/latest/reference/) beziehen. Informationen zu Transaktionsdatenoperationen finden Sie in der [QLDB Driver for](https://javadoc.io/doc/software.amazon.qldb/amazon-qldb-driver-java/latest/index.html) Java API-Referenz.

**Anmerkung**  
Gegebenenfalls enthalten einige Tutorial-Schritte unterschiedliche Befehle oder Codebeispiele für jede unterstützte Hauptversion des QLDB-Treibers für Java.

**Topics**
+ [Installation der Amazon QLDB-Java-Beispielanwendung](sample-app.java.md)
+ [Schritt 1: Erstellen Sie ein neues Hauptbuch](getting-started.java.step-1.md)
+ [Schritt 2: Testen Sie die Konnektivität zum Ledger](getting-started.java.step-2.md)
+ [Schritt 3: Erstellen Sie Tabellen, Indizes und Beispieldaten](getting-started.java.step-3.md)
+ [Schritt 4: Fragen Sie die Tabellen in einem Hauptbuch ab](getting-started.java.step-4.md)
+ [Schritt 5: Dokumente in einem Ledger ändern](getting-started.java.step-5.md)
+ [Schritt 6: Den Revisionsverlauf für ein Dokument anzeigen](getting-started.java.step-6.md)
+ [Schritt 7: Überprüfen Sie ein Dokument in einem Hauptbuch](getting-started.java.step-7.md)
+ [Schritt 8: Exportieren und validieren Sie Journaldaten in einem Ledger](getting-started.java.step-8.md)
+ [Schritt 9 (optional): Ressourcen bereinigen](getting-started.java.step-9.md)

# Installation der Amazon QLDB-Java-Beispielanwendung
<a name="sample-app.java"></a>

**Wichtig**  
Hinweis zum Ende des Supports: Bestandskunden können Amazon QLDB bis zum Ende des Supports am 31.07.2025 nutzen. Weitere Informationen finden Sie unter [Migrieren eines Amazon QLDB-Ledgers zu Amazon](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/) Aurora PostgreSQL.

In diesem Abschnitt wird beschrieben, wie Sie die bereitgestellte Amazon QLDB-Beispielanwendung für das step-by-step Java-Tutorial installieren und ausführen. Der Anwendungsfall für diese Beispielanwendung ist eine Datenbank der Straßenverkehrsbehörde, mit der die vollständigen Verlaufsinformationen über Fahrzeugzulassungen nachverfolgt werden.

[Die DMV-Beispielanwendung für Java ist Open Source im GitHub Repository aws-samples/ -java. amazon-qldb-dmv-sample](https://github.com/aws-samples/amazon-qldb-dmv-sample-java)

## Voraussetzungen
<a name="sample-app.java.prereqs"></a>

Bevor Sie beginnen, stellen Sie sicher, dass Sie den QLDB-Treiber für Java fertiggestellt haben. [Voraussetzungen](getting-started.java.md#getting-started.java.prereqs) Diese umfasst die folgenden Funktionen:

1. Melden Sie sich an für. AWS

1. Erstellen Sie einen Benutzer mit den entsprechenden QLDB-Berechtigungen. Um alle Schritte in diesem Tutorial ausführen zu können, benötigen Sie vollen Administratorzugriff auf Ihre Ledger-Ressource über die QLDB-API.

1. Wenn Sie eine andere IDE als verwenden AWS Cloud9, installieren Sie Java und gewähren Sie programmatischen Zugriff für die Entwicklung.

## Installation
<a name="sample-app.java.install"></a>

In den folgenden Schritten wird beschrieben, wie Sie die Beispielanwendung mit einer lokalen Entwicklungsumgebung herunterladen und einrichten. Oder Sie können die Einrichtung der Beispielanwendung automatisieren, indem Sie AWS Cloud9 als IDE eine CloudFormation Vorlage zur Bereitstellung Ihrer Entwicklungsressourcen verwenden.

### Lokale Entwicklungsumgebung
<a name="sample-app.java.local-ide"></a>

Diese Anweisungen beschreiben, wie Sie die QLDB-Java-Beispielanwendung mithilfe Ihrer eigenen Ressourcen und Entwicklungsumgebung herunterladen und installieren.

**So laden Sie die Beispielanwendung herunter und führen sie aus**

1. Geben Sie den folgenden Befehl ein, um die Beispielanwendung zu klonen. GitHub

------
#### [ 2.x ]

   ```
   git clone https://github.com/aws-samples/amazon-qldb-dmv-sample-java.git
   ```

------
#### [ 1.x ]

   ```
   git clone -b v1.2.0 https://github.com/aws-samples/amazon-qldb-dmv-sample-java.git
   ```

------

   Dieses Paket enthält die Gradle-Konfiguration und den vollständigen Code aus dem [Java-Lernprogramm](getting-started.java.tutorial.md).

1. Laden Sie die bereitgestellte Anwendung und führen Sie sie aus.
   + Wenn Sie Eclipse verwenden:

     1. Starten Sie Eclipse und wählen Sie im Menü **Eclipse** die Optionen **File (Datei)**, **Import (Importieren)** und dann **Existing Gradle Project (Bestehendes Gradle-Projekt)**.

     1. Durchsuchen Sie das Projekt-Stammverzeichnis und wählen Sie das Anwendungsverzeichnis, das die `build.gradle`-Datei enthält. Wählen Sie dann **Finish (Fertig stellen)**, um die Standard-Gradle-Einstellungen für den Import zu verwenden. 

     1. Sie können versuchen, das `ListLedgers`-Programm als Beispiel auszuführen. Öffnen Sie das Kontextmenü (rechte Maustaste) für die `ListLedgers.java`-Datei und wählen Sie **Run as Java Application (Als Java-Anwendung ausführen)** aus.
   + Wenn Sie IntelliJ verwenden:

     1. Starten Sie IntelliJ und wählen Sie im Menü **IntelliJ** **File (Datei)** und dann **Open (Öffnen)** aus.

     1. Durchsuchen Sie das Projekt-Stammverzeichnis und wählen Sie das Anwendungsverzeichnis, das die `build.gradle`-Datei enthält. Klicken Sie anschließend auf **OK**. Behalten Sie die Standardeinstellungen bei und klicken Sie erneut auf **OK**. 

     1. Sie können versuchen, das `ListLedgers`-Programm als Beispiel auszuführen. Öffnen Sie das Kontextmenü (Rechtsklick) für die `ListLedgers.java` Datei und wählen Sie **Ausführen '' ListLedgers**.

1. Fahren Sie mit [Schritt 1: Erstellen Sie ein neues Hauptbuch](getting-started.java.step-1.md) fort, um das Tutorial zu starten und ein Ledger zu erstellen.

### AWS Cloud9
<a name="sample-app.java.cfn-ac9"></a>

In diesen Anweisungen wird beschrieben, wie Sie die Einrichtung der Amazon QLDB-Beispielanwendung für Fahrzeugregistrierung für Java automatisieren, indem Sie [AWS Cloud9](https://aws.amazon.com/cloud9)sie als IDE verwenden. In diesem Handbuch verwenden Sie eine [CloudFormation](https://aws.amazon.com/cloudformation)-Vorlage, um Ihre Entwicklungsressourcen bereitzustellen.

Weitere Informationen zu AWS Cloud9 finden Sie im [AWS Cloud9 Benutzerhandbuch](https://docs.aws.amazon.com/cloud9/latest/user-guide/). Weitere Informationen zu CloudFormation finden Sie im [AWS CloudFormation -Benutzerhandbuch](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/).

**Topics**
+ [Teil 1: Stellen Sie Ihre Ressourcen bereit](#sample-app.java.cfn-ac9.step-1)
+ [Teil 2: Richten Sie Ihre IDE ein](#sample-app.java.cfn-ac9.step-2)
+ [Teil 3: Führen Sie die QLDB DMV-Beispielanwendung aus](#sample-app.java.cfn-ac9.step-3)

#### Teil 1: Stellen Sie Ihre Ressourcen bereit
<a name="sample-app.java.cfn-ac9.step-1"></a>

In diesem ersten Schritt stellen Sie die Ressourcen CloudFormation bereit, die für die Einrichtung Ihrer Entwicklungsumgebung mit der Amazon QLDB-Beispielanwendung erforderlich sind.

**Um die CloudFormation Konsole zu öffnen und die QLDB-Beispielanwendungsvorlage zu laden**

1. [Melden Sie sich bei der an AWS-Managementkonsole und öffnen Sie die CloudFormation Konsole unter https://console.aws.amazon.com /cloudformation.](https://console.aws.amazon.com/cloudformation/)

   Wechseln Sie zu einer Region, die QLDB unterstützt. Eine vollständige Liste finden Sie unter [Amazon QLDB-Endpunkte und Kontingente](https://docs.aws.amazon.com/general/latest/gr/qldb.html) in der. *Allgemeine AWS-Referenz* Der folgende Screenshot AWS-Managementkonsole zeigt die Region USA Ost (Nord-Virginia) als ausgewählt. AWS-Region  
![\[AWS-Managementkonsole zeigt USA Ost (Nord-Virginia) als ausgewählt AWS-Region.\]](http://docs.aws.amazon.com/de_de/qldb/latest/developerguide/images/cfn-ac9/aws-region-us-east-1.png)

1. Wählen Sie in der CloudFormation Konsole „**Stack erstellen**“ und anschließend „**Mit neuen Ressourcen (Standard)**“ aus.

1. Wählen Sie auf der Seite **Create stack (Stack erstellen)** unter **Specify template (Vorlage angeben)** die Option **Amazon S3 URL** aus.

1. Geben Sie die folgende URL ein und klicken Sie auf **Next (Weiter)**.

   ```
   https://amazon-qldb-assets.s3.amazonaws.com/templates/QLDB-DMV-SampleApp.yml
   ```

1. Geben Sie einen **Stack name (Stack-Namen)** ein (wie **qldb-sample-app**) und wählen Sie **Next (Weiter)** aus.

1. Sie können Tags nach Bedarf hinzufügen und die Standard-Optionen beibehalten. Wählen Sie anschließend **Weiter**.

1. Überprüfen Sie Ihre Stack-Einstellungen und klicken Sie auf **Create Stack (Stack erstellen)**. Es kann einige Minuten dauern, bis das CloudFormation Skript fertig ist.

   Dieses Skript stellt Ihrer AWS Cloud9 Umgebung eine zugehörige Amazon Elastic Compute Cloud (Amazon EC2) -Instance zur Verfügung, mit der Sie die QLDB-Beispielanwendung in diesem Tutorial ausführen. Es klont auch das [aws-samples/ amazon-qldb-dmv-sample -java-Repository](https://github.com/aws-samples/amazon-qldb-dmv-sample-java/) aus Ihrer Entwicklungsumgebung. GitHub AWS Cloud9 

#### Teil 2: Richten Sie Ihre IDE ein
<a name="sample-app.java.cfn-ac9.step-2"></a>

In diesem Schritt stellen Sie die Einrichtung Ihrer Cloud-Entwicklungsumgebung fertig. Sie laden ein bereitgestelltes Shell-Skript herunter und führen es aus, um Ihre AWS Cloud9 IDE mit den Abhängigkeiten der Beispielanwendung einzurichten.

**Um Ihre AWS Cloud9 Umgebung einzurichten**

1. Öffnen Sie die AWS Cloud9 Konsole unter [https://console.aws.amazon.com/cloud9/](https://console.aws.amazon.com/cloud9/).

1. Suchen Sie unter **Your environments (Ihre Umgebungen)** die Karte für die Umgebung mit der Bezeichnung **QLDB DMV Sample Application** und wählen Sie **Open IDE (IDE öffnen)** aus. Es kann eine Minute dauern, bis Ihre Umgebung geladen ist, wenn die zugrunde liegende EC2 Instance gestartet wird.

   Ihre AWS Cloud9 Umgebung ist mit den Systemabhängigkeiten vorkonfiguriert, die Sie für die Ausführung des Tutorials benötigen. Bestätigen Sie im Navigationsbereich **Environment (Umgebung)** Ihrer Konsole, dass Sie einen Ordner mit der Bezeichnung `QLDB DMV Sample Application` sehen. Der folgende Screenshot der AWS Cloud9 Konsole zeigt den Umgebungsordnerbereich der QLDB DMV-Beispielanwendung.  
![\[AWS Cloud9 Konsole mit dem Umgebungsordnerbereich für die QLDB DMV-Beispielanwendung.\]](http://docs.aws.amazon.com/de_de/qldb/latest/developerguide/images/cfn-ac9/cloud9-folders.png)

   Wenn Sie keinen Navigationsbereich sehen, blenden Sie die Registerkarte **Environment (Umgebung)** auf der linken Seite der Konsole ein/aus. Wenn Sie in dem Bereich keine Ordner sehen, aktivieren Sie mit dem Einstellungssymbol () die Option **Umgebungsstamm anzeigen**. ![\[Settings icon\]](http://docs.aws.amazon.com/de_de/qldb/latest/developerguide/images/settings.png)

1. Im unteren Bereich Ihrer Konsole sollten Sie ein `bash`-Terminal-Fenster sehen. Wenn Sie dies nicht sehen, wählen Sie **New Terminal (Neues Terminal)** aus dem Menü **Window (Fenster)** oben in der Konsole.

1. Laden Sie als Nächstes ein Setup-Skript herunter und führen Sie es aus, um OpenJDK 8 zu installieren. Falls zutreffend, checken Sie den entsprechenden Branch aus dem Git-Repository aus. Führen Sie in dem AWS Cloud9 Terminal, das Sie im vorherigen Schritt erstellt haben, die folgenden beiden Befehle nacheinander aus:

------
#### [ 2.x ]

   ```
   aws s3 cp s3://amazon-qldb-assets/setup-scripts/dmv-setup-v2.sh .
   ```

   ```
   sh dmv-setup-v2.sh
   ```

------
#### [ 1.x ]

   ```
   aws s3 cp s3://amazon-qldb-assets/setup-scripts/dmv-setup.sh .
   ```

   ```
   sh dmv-setup.sh
   ```

------

   Nachdem der Vorgang abgeschlossen ist, sollten Sie die folgende Nachricht im Terminal sehen:

   ```
   ** DMV Sample App setup completed , enjoy!! **
   ```

1. Nehmen Sie sich einen Moment Zeit, um den Code der Beispielanwendung zu durchsuchen AWS Cloud9, insbesondere im folgenden Verzeichnispfad:`src/main/java/software/amazon/qldb/tutorial`.

#### Teil 3: Führen Sie die QLDB DMV-Beispielanwendung aus
<a name="sample-app.java.cfn-ac9.step-3"></a>

In diesem Schritt erfahren Sie, wie Sie die Aufgaben der Amazon QLDB DMV-Beispielanwendung mithilfe von ausführen. AWS Cloud9 Um den Beispielcode auszuführen, kehren Sie zu Ihrem AWS Cloud9 Terminal zurück oder erstellen Sie ein neues Terminalfenster, wie Sie es in *Teil 2: IDE einrichten* getan haben.

**So führen Sie die Beispielanwendung aus**

1. Führen Sie den folgenden Befehl in Ihrem Terminal aus, um zum Projekt-Stammverzeichnis zu wechseln:

   ```
   cd ~/environment/amazon-qldb-dmv-sample-java
   ```

   Stellen Sie sicher, dass Sie die Beispiele im folgenden Verzeichnispfad ausführen.

   ```
   /home/ec2-user/environment/amazon-qldb-dmv-sample-java/
   ```

1. Der folgende Befehl zeigt die Gradle-Syntax zur Ausführung von einzelnen Aufgaben.

   ```
   ./gradlew run -Dtutorial=Task
   ```

   Führen Sie beispielsweise den folgenden Befehl aus, um alle Ledger in Ihrer AWS-Konto und der aktuellen Region aufzulisten.

   ```
   ./gradlew run -Dtutorial=ListLedgers
   ```

1. Fahren Sie mit [Schritt 1: Erstellen Sie ein neues Hauptbuch](getting-started.java.step-1.md) fort, um das Tutorial zu starten und ein Ledger zu erstellen.

1. (Optional) Wenn Sie das Tutorial abgeschlossen haben, bereinigen Sie Ihre CloudFormation -Ressourcen, wenn Sie sie nicht mehr benötigen.

   1. Öffnen Sie die CloudFormation Konsole unter [https://console.aws.amazon.com/cloudformation](https://console.aws.amazon.com/cloudformation/) und löschen Sie den Stack, den Sie in *Teil 1: Bereitstellen* Ihrer Ressourcen erstellt haben.

   1. Löschen Sie auch den AWS Cloud9 Stack, den die CloudFormation Vorlage für Sie erstellt hat.

# Schritt 1: Erstellen Sie ein neues Hauptbuch
<a name="getting-started.java.step-1"></a>

**Wichtig**  
Hinweis zum Ende des Supports: Bestandskunden können Amazon QLDB bis zum Ende des Supports am 31.07.2025 nutzen. Weitere Informationen finden Sie unter [Migrieren eines Amazon QLDB-Ledgers zu Amazon](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/) Aurora PostgreSQL.

In diesem Schritt erstellen Sie ein neues Amazon QLDB-Ledger mit dem Namen. `vehicle-registration`

**So erstellen Sie einen neuen Ledger**

1. Überprüfen Sie die folgende Datei (`Constants.java`), die konstante Werte enthält, die von allen anderen Programmen in diesem Tutorial verwendet werden.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonSystem;
   import com.amazon.ion.system.IonSystemBuilder;
   import com.fasterxml.jackson.databind.SerializationFeature;
   import com.fasterxml.jackson.dataformat.ion.IonObjectMapper;
   import com.fasterxml.jackson.dataformat.ion.ionvalue.IonValueMapper;
   
   /**
    * Constant values used throughout this tutorial.
    */
   public final class Constants {
       public static final int RETRY_LIMIT = 4;
       public static final String LEDGER_NAME = "vehicle-registration";
       public static final String STREAM_NAME = "vehicle-registration-stream";
       public static final String VEHICLE_REGISTRATION_TABLE_NAME = "VehicleRegistration";
       public static final String VEHICLE_TABLE_NAME = "Vehicle";
       public static final String PERSON_TABLE_NAME = "Person";
       public static final String DRIVERS_LICENSE_TABLE_NAME = "DriversLicense";
       public static final String VIN_INDEX_NAME = "VIN";
       public static final String PERSON_GOV_ID_INDEX_NAME = "GovId";
       public static final String VEHICLE_REGISTRATION_LICENSE_PLATE_NUMBER_INDEX_NAME = "LicensePlateNumber";
       public static final String DRIVER_LICENSE_NUMBER_INDEX_NAME = "LicenseNumber";
       public static final String DRIVER_LICENSE_PERSONID_INDEX_NAME = "PersonId";
       public static final String JOURNAL_EXPORT_S3_BUCKET_NAME_PREFIX = "qldb-tutorial-journal-export";
       public static final String USER_TABLES = "information_schema.user_tables";
       public static final String LEDGER_NAME_WITH_TAGS = "tags";
       public static final IonSystem SYSTEM = IonSystemBuilder.standard().build();
       public static final IonObjectMapper MAPPER = new IonValueMapper(SYSTEM);
   
       private Constants() { }
   
       static {
           MAPPER.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
       }
   }
   ```

------
#### [ 1.x ]

**Wichtig**  
Für das Amazon Ion-Paket müssen Sie den Namespace `com.amazon.ion` in Ihrer Anwendung verwenden. Das AWS SDK für Java hängt von einem anderen Ion-Paket unter dem Namespace ab`software.amazon.ion`, aber das ist ein Legacy-Paket, das nicht mit dem QLDB-Treiber kompatibel ist.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonSystem;
   import com.amazon.ion.system.IonSystemBuilder;
   import com.fasterxml.jackson.databind.SerializationFeature;
   import com.fasterxml.jackson.dataformat.ion.IonObjectMapper;
   import com.fasterxml.jackson.dataformat.ion.ionvalue.IonValueMapper;
   
   /**
    * Constant values used throughout this tutorial.
    */
   public final class Constants {
       public static final int RETRY_LIMIT = 4;
       public static final String LEDGER_NAME = "vehicle-registration";
       public static final String STREAM_NAME = "vehicle-registration-stream";
       public static final String VEHICLE_REGISTRATION_TABLE_NAME = "VehicleRegistration";
       public static final String VEHICLE_TABLE_NAME = "Vehicle";
       public static final String PERSON_TABLE_NAME = "Person";
       public static final String DRIVERS_LICENSE_TABLE_NAME = "DriversLicense";
       public static final String VIN_INDEX_NAME = "VIN";
       public static final String PERSON_GOV_ID_INDEX_NAME = "GovId";
       public static final String VEHICLE_REGISTRATION_LICENSE_PLATE_NUMBER_INDEX_NAME = "LicensePlateNumber";
       public static final String DRIVER_LICENSE_NUMBER_INDEX_NAME = "LicenseNumber";
       public static final String DRIVER_LICENSE_PERSONID_INDEX_NAME = "PersonId";
       public static final String JOURNAL_EXPORT_S3_BUCKET_NAME_PREFIX = "qldb-tutorial-journal-export";
       public static final String USER_TABLES = "information_schema.user_tables";
       public static final String LEDGER_NAME_WITH_TAGS = "tags";
       public static final IonSystem SYSTEM = IonSystemBuilder.standard().build();
       public static final IonObjectMapper MAPPER = new IonValueMapper(SYSTEM);
   
       private Constants() { }
   
       static {
           MAPPER.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
       }
   }
   ```

------
**Anmerkung**  
Diese `Constants` Klasse beinhaltet eine Instanz der Open-Source-Jackson-Klasse. `IonValueMapper` Sie können diesen Mapper verwenden, um Ihre [Amazon Ion](ion.md)-Daten bei Lese- und Schreibtransaktionen zu verarbeiten.

   Die `CreateLedger.java`-Datei verfügt auch über eine Abhängigkeit von folgendem Programm (`DescribeLedger.java`), das den aktuellen Status Ihres Ledgers beschreibt.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.model.DescribeLedgerRequest;
   import com.amazonaws.services.qldb.model.DescribeLedgerResult;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   /**
    * Describe a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class DescribeLedger {
       public static AmazonQLDB client = CreateLedger.getClient();
       public static final Logger log = LoggerFactory.getLogger(DescribeLedger.class);
   
       private DescribeLedger() { }
   
       public static void main(final String... args) {
           try {
   
               describe(Constants.LEDGER_NAME);
   
           } catch (Exception e) {
               log.error("Unable to describe a ledger!", e);
           }
       }
   
       /**
        * Describe a ledger.
        *
        * @param name
        *              Name of the ledger to describe.
        * @return {@link DescribeLedgerResult} from QLDB.
        */
       public static DescribeLedgerResult describe(final String name) {
           log.info("Let's describe ledger with name: {}...", name);
           DescribeLedgerRequest request = new DescribeLedgerRequest().withName(name);
           DescribeLedgerResult result = client.describeLedger(request);
           log.info("Success. Ledger description: {}", result);
           return result;
       }
   }
   ```

1. Kompilieren Sie das Programm `CreateLedger.java` und führen Sie es aus, um einen Ledger mit dem Namen `vehicle-registration` zu erstellen.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.client.builder.AwsClientBuilder;
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.AmazonQLDBClientBuilder;
   import com.amazonaws.services.qldb.model.CreateLedgerRequest;
   import com.amazonaws.services.qldb.model.CreateLedgerResult;
   import com.amazonaws.services.qldb.model.DescribeLedgerResult;
   import com.amazonaws.services.qldb.model.LedgerState;
   import com.amazonaws.services.qldb.model.PermissionsMode;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   /**
    * Create a ledger and wait for it to be active.
    * <p>
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class CreateLedger {
       public static final Logger log = LoggerFactory.getLogger(CreateLedger.class);
       public static final Long LEDGER_CREATION_POLL_PERIOD_MS = 10_000L;
       public static String endpoint = null;
       public static String region = null;
       public static AmazonQLDB client = getClient();
   
       private CreateLedger() {
       }
   
       /**
        * Build a low-level QLDB client.
        *
        * @return {@link AmazonQLDB} control plane client.
        */
       public static AmazonQLDB getClient() {
           AmazonQLDBClientBuilder builder = AmazonQLDBClientBuilder.standard();
           if (null != endpoint && null != region) {
               builder.setEndpointConfiguration(new AwsClientBuilder.EndpointConfiguration(endpoint, region));
           }
           return builder.build();
       }
   
       public static void main(final String... args) throws Exception {
           try {
               client = getClient();
   
               create(Constants.LEDGER_NAME);
   
               waitForActive(Constants.LEDGER_NAME);
   
           } catch (Exception e) {
               log.error("Unable to create the ledger!", e);
               throw e;
           }
       }
   
       /**
        * Create a new ledger with the specified ledger name.
        *
        * @param ledgerName Name of the ledger to be created.
        * @return {@link CreateLedgerResult} from QLDB.
        */
       public static CreateLedgerResult create(final String ledgerName) {
           log.info("Let's create the ledger with name: {}...", ledgerName);
           CreateLedgerRequest request = new CreateLedgerRequest()
                   .withName(ledgerName)
                   .withPermissionsMode(PermissionsMode.ALLOW_ALL);
           CreateLedgerResult result = client.createLedger(request);
           log.info("Success. Ledger state: {}.", result.getState());
           return result;
       }
   
       /**
        * Wait for a newly created ledger to become active.
        *
        * @param ledgerName Name of the ledger to wait on.
        * @return {@link DescribeLedgerResult} from QLDB.
        * @throws InterruptedException if thread is being interrupted.
        */
       public static DescribeLedgerResult waitForActive(final String ledgerName) throws InterruptedException {
           log.info("Waiting for ledger to become active...");
           while (true) {
               DescribeLedgerResult result = DescribeLedger.describe(ledgerName);
               if (result.getState().equals(LedgerState.ACTIVE.name())) {
                   log.info("Success. Ledger is active and ready to use.");
                   return result;
               }
               log.info("The ledger is still creating. Please wait...");
               Thread.sleep(LEDGER_CREATION_POLL_PERIOD_MS);
           }
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.AmazonQLDBClientBuilder;
   import com.amazonaws.services.qldb.model.CreateLedgerRequest;
   import com.amazonaws.services.qldb.model.CreateLedgerResult;
   import com.amazonaws.services.qldb.model.DescribeLedgerResult;
   import com.amazonaws.services.qldb.model.LedgerState;
   import com.amazonaws.services.qldb.model.PermissionsMode;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   /**
    * Create a ledger and wait for it to be active.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class CreateLedger {
       public static final Logger log = LoggerFactory.getLogger(CreateLedger.class);
       public static final Long LEDGER_CREATION_POLL_PERIOD_MS = 10_000L;
       public static AmazonQLDB client = getClient();
   
       private CreateLedger() { }
   
       /**
        * Build a low-level QLDB client.
        *
        * @return {@link AmazonQLDB} control plane client.
        */
       public static AmazonQLDB getClient() {
           return AmazonQLDBClientBuilder.standard().build();
       }
   
       public static void main(final String... args) throws Exception {
           try {
   
               create(Constants.LEDGER_NAME);
   
               waitForActive(Constants.LEDGER_NAME);
   
           } catch (Exception e) {
               log.error("Unable to create the ledger!", e);
               throw e;
           }
       }
   
       /**
        * Create a new ledger with the specified ledger name.
        *
        * @param ledgerName
        *              Name of the ledger to be created.
        * @return {@link CreateLedgerResult} from QLDB.
        */
       public static CreateLedgerResult create(final String ledgerName) {
           log.info("Let's create the ledger with name: {}...", ledgerName);
           CreateLedgerRequest request = new CreateLedgerRequest()
                   .withName(ledgerName)
                   .withPermissionsMode(PermissionsMode.ALLOW_ALL);
           CreateLedgerResult result = client.createLedger(request);
           log.info("Success. Ledger state: {}.", result.getState());
           return result;
       }
   
       /**
        * Wait for a newly created ledger to become active.
        *
        * @param ledgerName
        *              Name of the ledger to wait on.
        * @return {@link DescribeLedgerResult} from QLDB.
        * @throws InterruptedException if thread is being interrupted.
        */
       public static DescribeLedgerResult waitForActive(final String ledgerName) throws InterruptedException {
           log.info("Waiting for ledger to become active...");
           while (true) {
               DescribeLedgerResult result = DescribeLedger.describe(ledgerName);
               if (result.getState().equals(LedgerState.ACTIVE.name())) {
                   log.info("Success. Ledger is active and ready to use.");
                   return result;
               }
               log.info("The ledger is still creating. Please wait...");
               Thread.sleep(LEDGER_CREATION_POLL_PERIOD_MS);
           }
       }
   }
   ```

------
**Anmerkung**  
Im `createLedger`-Aufruf müssen Sie einen Ledger-Namen und einen Berechtigungsmodus angeben. Wir empfehlen, den `STANDARD` Berechtigungsmodus zu verwenden, um die Sicherheit Ihrer Ledger-Daten zu maximieren.
Wenn Sie einen Ledger erstellen, ist der *Löschschutz* standardmäßig aktiviert. Dies ist eine Funktion in QLDB, die verhindert, dass Ledger von Benutzern gelöscht werden. Sie haben die Möglichkeit, den Löschschutz bei der Ledger-Erstellung mithilfe der QLDB-API oder der () zu deaktivieren. AWS Command Line Interface AWS CLI
Optional können Sie auch Tags angeben, die Ihrem Ledger angefügt werden sollen.

Fahren Sie zum Überprüfen der Verbindung mit dem neuen Ledger mit [Schritt 2: Testen Sie die Konnektivität zum Ledger](getting-started.java.step-2.md) fort.

# Schritt 2: Testen Sie die Konnektivität zum Ledger
<a name="getting-started.java.step-2"></a>

**Wichtig**  
Hinweis zum Ende des Supports: Bestandskunden können Amazon QLDB bis zum Ende des Supports am 31.07.2025 nutzen. Weitere Informationen finden Sie unter [Migrieren eines Amazon QLDB-Ledgers zu Amazon](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/) Aurora PostgreSQL.

In diesem Schritt überprüfen Sie, ob Sie über den Transaktionsdaten-API-Endpunkt eine Verbindung zum `vehicle-registration` Ledger in Amazon QLDB herstellen können.

**So testen Sie die Verbindung zum Ledger**

1. Sehen Sie sich das folgende Programm (`ConnectToLedger.java`) an, das eine Datensitzungsverbindung zum Ledger herstellt. `vehicle-registration`

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import java.net.URI;
   import java.net.URISyntaxException;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.awssdk.auth.credentials.AwsCredentialsProvider;
   import software.amazon.awssdk.services.qldbsession.QldbSessionClient;
   import software.amazon.awssdk.services.qldbsession.QldbSessionClientBuilder;
   import software.amazon.qldb.QldbDriver;
   import software.amazon.qldb.RetryPolicy;
   
   /**
    * Connect to a session for a given ledger using default settings.
    * <p>
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class ConnectToLedger {
       public static final Logger log = LoggerFactory.getLogger(ConnectToLedger.class);
       public static AwsCredentialsProvider credentialsProvider;
       public static String endpoint = null;
       public static String ledgerName = Constants.LEDGER_NAME;
       public static String region = null;
       public static QldbDriver driver;
   
       private ConnectToLedger() {
       }
   
       /**
        * Create a pooled driver for creating sessions.
        *
        * @param retryAttempts How many times the transaction will be retried in
        * case of a retryable issue happens like Optimistic Concurrency Control exception,
        * server side failures or network issues.
        * @return The pooled driver for creating sessions.
        */
       public static QldbDriver createQldbDriver(int retryAttempts) {
           QldbSessionClientBuilder builder = getAmazonQldbSessionClientBuilder();
           return QldbDriver.builder()
                                .ledger(ledgerName)
                                .transactionRetryPolicy(RetryPolicy
                                      .builder()
                                      .maxRetries(retryAttempts)
                                      .build())
                                .sessionClientBuilder(builder)
                                .build();
       }
   
       /**
        * Create a pooled driver for creating sessions.
        *
        * @return The pooled driver for creating sessions.
        */
       public static QldbDriver createQldbDriver() {
           QldbSessionClientBuilder builder = getAmazonQldbSessionClientBuilder();
           return QldbDriver.builder()
               .ledger(ledgerName)
               .transactionRetryPolicy(RetryPolicy.builder()
                                                  .maxRetries(Constants.RETRY_LIMIT).build())
               .sessionClientBuilder(builder)
               .build();
       }
   
       /**
        * Creates a QldbSession builder that is passed to the QldbDriver to connect to the Ledger.
        *
        * @return An instance of the AmazonQLDBSessionClientBuilder
        */
       public static QldbSessionClientBuilder getAmazonQldbSessionClientBuilder() {
           QldbSessionClientBuilder builder = QldbSessionClient.builder();
           if (null != endpoint && null != region) {
               try {
                   builder.endpointOverride(new URI(endpoint));
               } catch (URISyntaxException e) {
                   throw new IllegalArgumentException(e);
               }
           }
           if (null != credentialsProvider) {
               builder.credentialsProvider(credentialsProvider);
           }
           return builder;
       }
   
       /**
        * Create a pooled driver for creating sessions.
        *
        * @return The pooled driver for creating sessions.
        */
       public static QldbDriver getDriver() {
           if (driver == null) {
               driver = createQldbDriver();
           }
           return driver;
       }
   
   
       public static void main(final String... args) {
           Iterable<String> tables = ConnectToLedger.getDriver().getTableNames();
           log.info("Existing tables in the ledger:");
           for (String table : tables) {
               log.info("- {} ", table);
           }
       }
   }
   ```

**Anmerkung**  
Um Datenoperationen in Ihrem Ledger auszuführen, müssen Sie eine Instanz der `QldbDriver` Klasse erstellen, um eine Verbindung zu einem bestimmten Ledger herzustellen. Dies ist ein anderes Client-Objekt als der `AmazonQLDB`-Client, den Sie im vorherigen Schritt zum Erstellen des Ledgers verwendet haben. Dieser vorherige Client wird nur verwendet, um die in der aufgeführten Verwaltungs-API-Operationen auszuführen. [Amazon QLDB API-Referenz](api-reference.md)
Erstellen Sie zunächst ein `QldbDriver`-Objekt. Beim Erstellen dieses Treibers müssen Sie einen Ledger-Namen angeben.  
Dann können Sie die Methode `execute` dieses Treibers verwenden, um PartiQL-Anweisungen auszuführen.
Optional können Sie eine maximale Anzahl von Wiederholungsversuchen für Transaktionsausnahmen angeben. Die `execute` Methode versucht automatisch, Konflikte mit optimistischer Parallelitätskontrolle (OCC) und andere häufig auftretende vorübergehende Ausnahmen bis zu diesem konfigurierbaren Limit erneut durchzuführen. Der Standardwert ist `4`.  
Wenn die Transaktion weiterhin fehlschlägt, nachdem das Limit erreicht ist, löst der Treiber die Ausnahme aus. Weitere Informationen hierzu finden Sie unter [Grundlegendes zur Wiederholungsrichtlinie mit dem Treiber in Amazon QLDB](driver-retry-policy.md).

------
#### [ 1.x ]

   ```
   /*
    * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.auth.AWSCredentialsProvider;
   import com.amazonaws.client.builder.AwsClientBuilder;
   import com.amazonaws.services.qldbsession.AmazonQLDBSessionClientBuilder;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.PooledQldbDriver;
   import software.amazon.qldb.QldbDriver;
   import software.amazon.qldb.QldbSession;
   import software.amazon.qldb.exceptions.QldbClientException;
   
   /**
    * Connect to a session for a given ledger using default settings.
    * <p>
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class ConnectToLedger {
       public static final Logger log = LoggerFactory.getLogger(ConnectToLedger.class);
       public static AWSCredentialsProvider credentialsProvider;
       public static String endpoint = null;
       public static String ledgerName = Constants.LEDGER_NAME;
       public static String region = null;
       private static PooledQldbDriver driver;
   
       private ConnectToLedger() {
       }
   
       /**
        * Create a pooled driver for creating sessions.
        *
        * @return The pooled driver for creating sessions.
        */
       public static PooledQldbDriver createQldbDriver() {
           AmazonQLDBSessionClientBuilder builder = AmazonQLDBSessionClientBuilder.standard();
           if (null != endpoint && null != region) {
               builder.setEndpointConfiguration(new AwsClientBuilder.EndpointConfiguration(endpoint, region));
           }
           if (null != credentialsProvider) {
               builder.setCredentials(credentialsProvider);
           }
           return PooledQldbDriver.builder()
                   .withLedger(ledgerName)
                   .withRetryLimit(Constants.RETRY_LIMIT)
                   .withSessionClientBuilder(builder)
                   .build();
       }
   
       /**
        * Create a pooled driver for creating sessions.
        *
        * @return The pooled driver for creating sessions.
        */
       public static PooledQldbDriver getDriver() {
           if (driver == null) {
               driver = createQldbDriver();
           }
           return driver;
       }
   
       /**
        * Connect to a ledger through a {@link QldbDriver}.
        *
        * @return {@link QldbSession}.
        */
       public static QldbSession createQldbSession() {
           return getDriver().getSession();
       }
   
       public static void main(final String... args) {
           try (QldbSession qldbSession = createQldbSession()) {
               log.info("Listing table names ");
               for (String tableName : qldbSession.getTableNames()) {
                   log.info(tableName);
               }
           } catch (QldbClientException e) {
               log.error("Unable to create session.", e);
           }
       }
   }
   ```

**Anmerkung**  
Um Datenoperationen auf Ihrem Ledger auszuführen, müssen Sie eine Instance der `PooledQldbDriver`- oder `QldbDriver`-Klasse erstellen, um eine Verbindung zu einem bestimmten Ledger herzustellen. Dies ist ein anderes Client-Objekt als der `AmazonQLDB`-Client, den Sie im vorherigen Schritt zum Erstellen des Ledgers verwendet haben. Dieser vorherige Client wird nur verwendet, um die in der aufgeführten Verwaltungs-API-Operationen auszuführen. [Amazon QLDB API-Referenz](api-reference.md)  
Wir empfehlen die Verwendung, `PooledQldbDriver` es sei denn, Sie müssen einen benutzerdefinierten Sitzungspool mit implementieren`QldbDriver`. Die Standard-Pool-Größe für `PooledQldbDriver` ist die [maximale Anzahl offener HTTP-Verbindungen](https://docs.aws.amazon.com/AWSJavaSDK/latest/javadoc/com/amazonaws/ClientConfiguration.html#getMaxConnections--), die der Sitzungs-Client zulässt.
Erstellen Sie zunächst ein `PooledQldbDriver`-Objekt. Beim Erstellen dieses Treibers müssen Sie einen Ledger-Namen angeben.  
Dann können Sie die Methode `execute` dieses Treibers verwenden, um PartiQL-Anweisungen auszuführen. Sie können auch manuell eine Sitzung aus diesem Pool-Treiberobjekt erstellen und die Methode `execute` der Sitzung verwenden. Eine Sitzung stellt eine einzelne Verbindung mit dem Konto dar.
Optional können Sie eine maximale Anzahl von Wiederholungsversuchen für Transaktionsausnahmen angeben. Die `execute` Methode versucht automatisch, Konflikte mit optimistischer Parallelitätskontrolle (OCC) und andere häufig auftretende vorübergehende Ausnahmen bis zu diesem konfigurierbaren Limit erneut durchzuführen. Der Standardwert ist `4`.  
Wenn die Transaktion weiterhin fehlschlägt, nachdem das Limit erreicht ist, löst der Treiber die Ausnahme aus. Weitere Informationen hierzu finden Sie unter [Grundlegendes zur Wiederholungsrichtlinie mit dem Treiber in Amazon QLDB](driver-retry-policy.md).

------

1. Kompilieren Sie das `ConnectToLedger.java` Programm und führen Sie es aus, um die Konnektivität Ihrer Datensitzung mit dem Ledger zu testen. `vehicle-registration`

**Überschreiben der AWS-Region**

Die Beispielanwendung stellt in Ihrer Standardeinstellung eine Verbindung zu QLDB her AWS-Region, die Sie wie im Schritt mit den Voraussetzungen beschrieben festlegen können. [Einstellung Ihrer AWS Standardanmeldedaten und Region](getting-started.java.md#getting-started.java.credentials) Sie können die Region auch ändern, indem Sie die Eigenschaften des QLDB-Session-Client-Builders ändern.

------
#### [ 2.x ]

Im folgenden Codebeispiel wird ein neues `QldbSessionClientBuilder`-Objekt instanziiert.

```
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.qldbsession.QldbSessionClientBuilder;

// This client builder will default to US East (Ohio)
QldbSessionClientBuilder builder = QldbSessionClient.builder()
    .region(Region.US_EAST_2);
```

Sie können die `region` Methode verwenden, um Ihren Code gegen QLDB in jeder Region auszuführen, in der er verfügbar ist. Eine vollständige Liste finden Sie unter [Amazon QLDB-Endpunkte und Kontingente](https://docs.aws.amazon.com/general/latest/gr/qldb.html) in der. *Allgemeine AWS-Referenz*

------
#### [ 1.x ]

Im folgenden Codebeispiel wird ein neues `AmazonQLDBSessionClientBuilder`-Objekt instanziiert.

```
import com.amazonaws.regions.Regions;
import com.amazonaws.services.qldbsession.AmazonQLDBSessionClientBuilder;

// This client builder will default to US East (Ohio)
AmazonQLDBSessionClientBuilder builder = AmazonQLDBSessionClientBuilder.standard()
    .withRegion(Regions.US_EAST_2);
```

Sie können die `withRegion` Methode verwenden, um Ihren Code gegen QLDB in jeder Region auszuführen, in der er verfügbar ist. Eine vollständige Liste finden Sie unter [Amazon QLDB-Endpunkte und Kontingente](https://docs.aws.amazon.com/general/latest/gr/qldb.html) in der. *Allgemeine AWS-Referenz*

------

Fahren Sie zum Erstellen von Tabellen im `vehicle-registration`-Ledger mit [Schritt 3: Erstellen Sie Tabellen, Indizes und Beispieldaten](getting-started.java.step-3.md) fort.

# Schritt 3: Erstellen Sie Tabellen, Indizes und Beispieldaten
<a name="getting-started.java.step-3"></a>

**Wichtig**  
Hinweis zum Ende des Supports: Bestandskunden können Amazon QLDB bis zum Ende des Supports am 31.07.2025 nutzen. Weitere Informationen finden Sie unter [Migrieren eines Amazon QLDB-Ledgers zu Amazon](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/) Aurora PostgreSQL.

Wenn Ihr Amazon QLDB-Ledger aktiv ist und Verbindungen akzeptiert, können Sie damit beginnen, Tabellen mit Daten über Fahrzeuge, deren Besitzer und deren Zulassungsinformationen zu erstellen. Nach dem Erstellen der Tabellen und Indizes können Sie Daten in diese laden.

In diesem Schritt erstellen Sie vier Tabellen im `vehicle-registration`-Ledger:
+ `VehicleRegistration`
+ `Vehicle`
+ `Person`
+ `DriversLicense`

Außerdem erzeugen Sie die folgenden Indizes.


****  

| Tabellenname | Feld | 
| --- | --- | 
| VehicleRegistration | VIN | 
| VehicleRegistration | LicensePlateNumber | 
| Vehicle | VIN | 
| Person | GovId | 
| DriversLicense | LicenseNumber | 
| DriversLicense | PersonId | 

Beim Einfügen von Beispieldaten fügen Sie zunächst Dokumente in die `Person`-Tabelle ein. Anschließend verwenden Sie die vom System zugewiesene `id` aus den `Person`-Dokumenten, um die entsprechenden Felder in den relevanten `VehicleRegistration`- und `DriversLicense`-Dokumenten auszufüllen.

**Tipp**  
Es hat sich bewährt, das vom System zugewiesene `id` Dokument als Fremdschlüssel zu verwenden. Sie können zwar Felder definieren, die eindeutige Kennungen (z. B. eine Kfz-VIN) sein sollen, die echte eindeutige Kennung eines Dokuments ist aber seine `id`. Dieses Feld ist in den Metadaten des Dokuments enthalten, die Sie in der *festgeschriebenen Ansicht* (d. h. in der vom System definierten Ansicht der Tabelle) abrufen können.  
Weitere Hinweise zu Ansichten in QLDB finden Sie unter. [Schlüsselkonzepte](ledger-structure.md) Weitere Informationen zu Metadaten finden Sie unter [Metadaten von Dokumenten werden abgefragt](working.metadata.md).

**So richten Sie den Beispiel-Stack ein**

1. Überprüfen Sie die folgenden `.java`-Dateien: Diese Modellklassen stellen Dokumente dar, die Sie in den `vehicle-registration`-Tabellen speichern. Sie können in das und vom Amazon Ion-Format serialisiert werden.
**Anmerkung**  
[Amazon QLDB-Dokumente](ql-reference.docs.md)werden im Ion-Format gespeichert, das eine Obermenge von JSON ist. Sie können also die FasterXML Jackson-Bibliothek verwenden, um die Daten in JSON zu modellieren.

   1. `DriversLicense.java`

      ```
      /*
       * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
      import com.fasterxml.jackson.databind.annotation.JsonSerialize;
      import software.amazon.qldb.tutorial.model.streams.RevisionData;
      
      import java.time.LocalDate;
      
      /**
       * Represents a driver's license, serializable to (and from) Ion.
       */
      public final class DriversLicense implements RevisionData {
          private final String personId;
          private final String licenseNumber;
          private final String licenseType;
      
          @JsonSerialize(using = IonLocalDateSerializer.class)
          @JsonDeserialize(using = IonLocalDateDeserializer.class)
          private final LocalDate validFromDate;
      
          @JsonSerialize(using = IonLocalDateSerializer.class)
          @JsonDeserialize(using = IonLocalDateDeserializer.class)
          private final LocalDate validToDate;
      
          @JsonCreator
          public DriversLicense(@JsonProperty("PersonId") final String personId,
                                @JsonProperty("LicenseNumber") final String licenseNumber,
                                @JsonProperty("LicenseType") final String licenseType,
                                @JsonProperty("ValidFromDate") final LocalDate validFromDate,
                                @JsonProperty("ValidToDate") final LocalDate validToDate) {
              this.personId = personId;
              this.licenseNumber = licenseNumber;
              this.licenseType = licenseType;
              this.validFromDate = validFromDate;
              this.validToDate = validToDate;
          }
      
          @JsonProperty("PersonId")
          public String getPersonId() {
              return personId;
          }
      
          @JsonProperty("LicenseNumber")
          public String getLicenseNumber() {
              return licenseNumber;
          }
      
          @JsonProperty("LicenseType")
          public String getLicenseType() {
              return licenseType;
          }
      
          @JsonProperty("ValidFromDate")
          public LocalDate getValidFromDate() {
              return  validFromDate;
          }
      
          @JsonProperty("ValidToDate")
          public LocalDate getValidToDate() {
              return  validToDate;
          }
      
          @Override
          public String toString() {
              return "DriversLicense{" +
                      "personId='" + personId + '\'' +
                      ", licenseNumber='" + licenseNumber + '\'' +
                      ", licenseType='" + licenseType + '\'' +
                      ", validFromDate=" + validFromDate +
                      ", validToDate=" + validToDate +
                      '}';
          }
      }
      ```

   1. `Person.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import java.time.LocalDate;
      
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
      import com.fasterxml.jackson.databind.annotation.JsonSerialize;
      
      import software.amazon.qldb.TransactionExecutor;
      import software.amazon.qldb.tutorial.Constants;
      import software.amazon.qldb.tutorial.model.streams.RevisionData;
      
      /**
       * Represents a person, serializable to (and from) Ion.
       */ 
      public final class Person implements RevisionData {
          private final String firstName;
          private final String lastName;
      
          @JsonSerialize(using = IonLocalDateSerializer.class)
          @JsonDeserialize(using = IonLocalDateDeserializer.class)
          private final LocalDate dob;
          private final String govId;
          private final String govIdType;
          private final String address;
      
          @JsonCreator
          public Person(@JsonProperty("FirstName") final String firstName,
                        @JsonProperty("LastName") final String lastName,
                        @JsonProperty("DOB") final LocalDate dob,
                        @JsonProperty("GovId") final String govId,
                        @JsonProperty("GovIdType") final String govIdType,
                        @JsonProperty("Address") final String address) {
              this.firstName = firstName;
              this.lastName = lastName;
              this.dob = dob;
              this.govId = govId;
              this.govIdType = govIdType;
              this.address = address;
          }
      
          @JsonProperty("Address")
          public String getAddress() {
              return address;
          }
      
          @JsonProperty("DOB")
          public LocalDate getDob() {
              return dob;
          }
      
          @JsonProperty("FirstName")
          public String getFirstName() {
              return firstName;
          }
      
          @JsonProperty("LastName")
          public String getLastName() {
              return lastName;
          }
      
          @JsonProperty("GovId")
          public String getGovId() {
              return govId;
          }
      
          @JsonProperty("GovIdType")
          public String getGovIdType() {
              return govIdType;
          }
      
          /**
           * This returns the unique document ID given a specific government ID.
           *
           * @param txn
           *              A transaction executor object.
           * @param govId
           *              The government ID of a driver.
           * @return the unique document ID.
           */
          public static String getDocumentIdByGovId(final TransactionExecutor txn, final String govId) {
              return SampleData.getDocumentId(txn, Constants.PERSON_TABLE_NAME, "GovId", govId);
          }
      
          @Override
          public String toString() {
              return "Person{" +
                      "firstName='" + firstName + '\'' +
                      ", lastName='" + lastName + '\'' +
                      ", dob=" + dob +
                      ", govId='" + govId + '\'' +
                      ", govIdType='" + govIdType + '\'' +
                      ", address='" + address + '\'' +
                      '}';
          }
      }
      ```

   1. `VehicleRegistration.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
      import com.fasterxml.jackson.databind.annotation.JsonSerialize;
      import software.amazon.qldb.TransactionExecutor;
      import software.amazon.qldb.tutorial.Constants;
      import software.amazon.qldb.tutorial.model.streams.RevisionData;
      
      import java.math.BigDecimal;
      import java.time.LocalDate;
      
      /**
       * Represents a vehicle registration, serializable to (and from) Ion.
       */ 
      public final class VehicleRegistration implements RevisionData {
      
          private final String vin;
          private final String licensePlateNumber;
          private final String state;
          private final String city;
          private final BigDecimal pendingPenaltyTicketAmount;
          private final LocalDate validFromDate;
          private final LocalDate validToDate;
          private final Owners owners;
      
          @JsonCreator
          public VehicleRegistration(@JsonProperty("VIN") final String vin,
                                     @JsonProperty("LicensePlateNumber") final String licensePlateNumber,
                                     @JsonProperty("State") final String state,
                                     @JsonProperty("City") final String city,
                                     @JsonProperty("PendingPenaltyTicketAmount") final BigDecimal pendingPenaltyTicketAmount,
                                     @JsonProperty("ValidFromDate") final LocalDate validFromDate,
                                     @JsonProperty("ValidToDate") final LocalDate validToDate,
                                     @JsonProperty("Owners") final Owners owners) {
              this.vin = vin;
              this.licensePlateNumber = licensePlateNumber;
              this.state = state;
              this.city = city;
              this.pendingPenaltyTicketAmount = pendingPenaltyTicketAmount;
              this.validFromDate = validFromDate;
              this.validToDate = validToDate;
              this.owners = owners;
          }
      
          @JsonProperty("City")
          public String getCity() {
              return city;
          }
      
          @JsonProperty("LicensePlateNumber")
          public String getLicensePlateNumber() {
              return licensePlateNumber;
          }
      
          @JsonProperty("Owners")
          public Owners getOwners() {
              return owners;
          }
      
          @JsonProperty("PendingPenaltyTicketAmount")
          public BigDecimal getPendingPenaltyTicketAmount() {
              return pendingPenaltyTicketAmount;
          }
      
          @JsonProperty("State")
          public String getState() {
              return state;
          }
      
          @JsonProperty("ValidFromDate")
          @JsonSerialize(using = IonLocalDateSerializer.class)
          @JsonDeserialize(using = IonLocalDateDeserializer.class)
          public LocalDate getValidFromDate() {
              return validFromDate;
          }
      
          @JsonProperty("ValidToDate")
          @JsonSerialize(using = IonLocalDateSerializer.class)
          @JsonDeserialize(using = IonLocalDateDeserializer.class)
          public LocalDate getValidToDate() {
              return validToDate;
          }
      
          @JsonProperty("VIN")
          public String getVin() {
              return vin;
          }
      
          /**
           * Returns the unique document ID of a vehicle given a specific VIN.
           *
           * @param txn
           *              A transaction executor object.
           * @param vin
           *              The VIN of a vehicle.
           * @return the unique document ID of the specified vehicle.
           */
          public static String getDocumentIdByVin(final TransactionExecutor txn, final String vin) {
              return SampleData.getDocumentId(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME, "VIN", vin);
          }
      
          @Override
          public String toString() {
              return "VehicleRegistration{" +
                      "vin='" + vin + '\'' +
                      ", licensePlateNumber='" + licensePlateNumber + '\'' +
                      ", state='" + state + '\'' +
                      ", city='" + city + '\'' +
                      ", pendingPenaltyTicketAmount=" + pendingPenaltyTicketAmount +
                      ", validFromDate=" + validFromDate +
                      ", validToDate=" + validToDate +
                      ", owners=" + owners +
                      '}';
          }
      }
      ```

   1. `Vehicle.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      import software.amazon.qldb.tutorial.model.streams.RevisionData;
      
      /**
       * Represents a vehicle, serializable to (and from) Ion.
       */
      public final class Vehicle implements RevisionData {
          private final String vin;
          private final String type;
          private final int year;
          private final String make;
          private final String model;
          private final String color;
      
          @JsonCreator
          public Vehicle(@JsonProperty("VIN") final String vin,
                         @JsonProperty("Type") final String type,
                         @JsonProperty("Year") final int year,
                         @JsonProperty("Make") final String make,
                         @JsonProperty("Model") final String model,
                         @JsonProperty("Color") final String color) {
              this.vin = vin;
              this.type = type;
              this.year = year;
              this.make = make;
              this.model = model;
              this.color = color;
          }
      
          @JsonProperty("Color")
          public String getColor() {
              return color;
          }
      
          @JsonProperty("Make")
          public String getMake() {
              return make;
          }
      
          @JsonProperty("Model")
          public String getModel() {
              return model;
          }
      
          @JsonProperty("Type")
          public String getType() {
              return type;
          }
      
          @JsonProperty("VIN")
          public String getVin() {
              return vin;
          }
      
          @JsonProperty("Year")
          public int getYear() {
              return year;
          }
      
          @Override
          public String toString() {
              return "Vehicle{" +
                      "vin='" + vin + '\'' +
                      ", type='" + type + '\'' +
                      ", year=" + year +
                      ", make='" + make + '\'' +
                      ", model='" + model + '\'' +
                      ", color='" + color + '\'' +
                      '}';
          }
      }
      ```

   1. `Owner.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.fasterxml.jackson.annotation.JsonProperty;
      
      /**
       * Represents a vehicle owner, serializable to (and from) Ion.
       */ 
      public final class Owner {
          private final String personId;
      
          public Owner(@JsonProperty("PersonId") final String personId) {
              this.personId = personId;
          }
      
          @JsonProperty("PersonId")
          public String getPersonId() {
              return personId;
          }
      
          @Override
          public String toString() {
              return "Owner{" +
                      "personId='" + personId + '\'' +
                      '}';
          }
      }
      ```

   1. `Owners.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.fasterxml.jackson.annotation.JsonProperty;
      
      import java.util.List;
      
      /**
       * Represents a set of owners for a given vehicle, serializable to (and from) Ion.
       */ 
      public final class Owners {
          private final Owner primaryOwner;
          private final List<Owner> secondaryOwners;
      
          public Owners(@JsonProperty("PrimaryOwner") final Owner primaryOwner,
                        @JsonProperty("SecondaryOwners") final List<Owner> secondaryOwners) {
              this.primaryOwner = primaryOwner;
              this.secondaryOwners = secondaryOwners;
          }
      
          @JsonProperty("PrimaryOwner")
          public Owner getPrimaryOwner() {
              return primaryOwner;
          }
      
          @JsonProperty("SecondaryOwners")
          public List<Owner> getSecondaryOwners() {
              return secondaryOwners;
          }
      
          @Override
          public String toString() {
              return "Owners{" +
                      "primaryOwner=" + primaryOwner +
                      ", secondaryOwners=" + secondaryOwners +
                      '}';
          }
      }
      ```

   1. `DmlResultDocument.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      
      /**
       * Contains information about an individual document inserted or modified
       * as a result of DML.
       */
      public class DmlResultDocument {
      
          private String documentId;
      
          @JsonCreator
          public DmlResultDocument(@JsonProperty("documentId") final String documentId) {
              this.documentId = documentId;
          }
      
          public String getDocumentId() {
              return documentId;
          }
      
          @Override
          public String toString() {
              return "DmlResultDocument{"
                  + "documentId='" + documentId + '\''
                  + '}';
          }
      }
      ```

   1. `RevisionData.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model.streams;
      
      /**
       * Allows modeling the content of all revisions as a generic revision data. Used
       * in the {@link Revision} and extended by domain models in {@link
       * software.amazon.qldb.tutorial.model} to make it easier to write the {@link
       * Revision.RevisionDataDeserializer} that must deserialize the {@link
       * Revision#data} from different domain models.
       */
      public interface RevisionData { }
      ```

   1. `RevisionMetadata.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import com.amazon.ion.IonInt;
      import com.amazon.ion.IonString;
      import com.amazon.ion.IonStruct;
      import com.amazon.ion.IonTimestamp;
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      import com.fasterxml.jackson.databind.annotation.JsonSerialize;
      import com.fasterxml.jackson.dataformat.ion.IonTimestampSerializers;
      import org.slf4j.Logger;
      import org.slf4j.LoggerFactory;
      
      import java.util.Date;
      import java.util.Objects;
      
      /**
       * Represents the metadata field of a QLDB Document
       */
      public class RevisionMetadata {
          private static final Logger log = LoggerFactory.getLogger(RevisionMetadata.class);
          private final String id;
          private final long version;
          @JsonSerialize(using = IonTimestampSerializers.IonTimestampJavaDateSerializer.class)
          private final Date txTime;
          private final String txId;
      
          @JsonCreator
          public RevisionMetadata(@JsonProperty("id") final String id,
                                  @JsonProperty("version") final long version,
                                  @JsonProperty("txTime") final Date txTime,
                                  @JsonProperty("txId") final String txId) {
              this.id = id;
              this.version = version;
              this.txTime = txTime;
              this.txId = txId;
          }
      
          /**
           * Gets the unique ID of a QLDB document.
           *
           * @return the document ID.
           */
          public String getId() {
              return id;
          }
      
          /**
           * Gets the version number of the document in the document's modification history.
           * @return the version number.
           */
          public long getVersion() {
              return version;
          }
      
          /**
           * Gets the time during which the document was modified.
           *
           * @return the transaction time.
           */
          public Date getTxTime() {
              return txTime;
          }
      
          /**
           * Gets the transaction ID associated with this document.
           *
           * @return the transaction ID.
           */
          public String getTxId() {
              return txId;
          }
      
          public static RevisionMetadata fromIon(final IonStruct ionStruct) {
              if (ionStruct == null) {
                  throw new IllegalArgumentException("Metadata cannot be null");
              }
              try {
                  IonString id = (IonString) ionStruct.get("id");
                  IonInt version = (IonInt) ionStruct.get("version");
                  IonTimestamp txTime = (IonTimestamp) ionStruct.get("txTime");
                  IonString txId = (IonString) ionStruct.get("txId");
                  if (id == null || version == null || txTime == null || txId == null) {
                      throw new IllegalArgumentException("Document is missing required fields");
                  }
                  return new RevisionMetadata(id.stringValue(), version.longValue(), new Date(txTime.getMillis()), txId.stringValue());
              } catch (ClassCastException e) {
                  log.error("Failed to parse ion document");
                  throw new IllegalArgumentException("Document members are not of the correct type", e);
              }
          }
      
          /**
           * Converts a {@link RevisionMetadata} object to a string.
           *
           * @return the string representation of the {@link QldbRevision} object.
           */
          @Override
          public String toString() {
              return "Metadata{"
                      + "id='" + id + '\''
                      + ", version=" + version
                      + ", txTime=" + txTime
                      + ", txId='" + txId
                      + '\''
                      + '}';
          }
      
          /**
           * Check whether two {@link RevisionMetadata} objects are equivalent.
           *
           * @return {@code true} if the two objects are equal, {@code false} otherwise.
           */
          @Override
          public boolean equals(Object o) {
              if (this == o) { return true; }
              if (o == null || getClass() != o.getClass()) { return false; }
              RevisionMetadata metadata = (RevisionMetadata) o;
              return version == metadata.version
                      && id.equals(metadata.id)
                      && txTime.equals(metadata.txTime)
                      && txId.equals(metadata.txId);
          }
      
          /**
           * Generate a hash code for the {@link RevisionMetadata} object.
           *
           * @return the hash code.
           */
          @Override
          public int hashCode() {
              // CHECKSTYLE:OFF - Disabling as we are generating a hashCode of multiple properties.
              return Objects.hash(id, version, txTime, txId);
              // CHECKSTYLE:ON
          }
      }
      ```

   1. `QldbRevision.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import com.amazon.ion.IonBlob;
      import com.amazon.ion.IonStruct;
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      import org.slf4j.Logger;
      import org.slf4j.LoggerFactory;
      import software.amazon.qldb.tutorial.Constants;
      import software.amazon.qldb.tutorial.Verifier;
      
      import java.io.IOException;
      import java.util.Arrays;
      import java.util.Objects;
      
      /**
       * Represents a QldbRevision including both user data and metadata.
       */
      public final class QldbRevision {
          private static final Logger log = LoggerFactory.getLogger(QldbRevision.class);
      
          private final BlockAddress blockAddress;
          private final RevisionMetadata metadata;
          private final byte[] hash;
          private final byte[] dataHash;
          private final IonStruct data;
      
          @JsonCreator
          public QldbRevision(@JsonProperty("blockAddress") final BlockAddress blockAddress,
                              @JsonProperty("metadata") final RevisionMetadata metadata,
                              @JsonProperty("hash") final byte[] hash,
                              @JsonProperty("dataHash") final byte[] dataHash,
                              @JsonProperty("data") final IonStruct data) {
              this.blockAddress = blockAddress;
              this.metadata = metadata;
              this.hash = hash;
              this.dataHash = dataHash;
              this.data = data;
          }
      
          /**
           * Gets the unique ID of a QLDB document.
           *
           * @return the {@link BlockAddress} object.
           */
          public BlockAddress getBlockAddress() {
              return blockAddress;
          }
      
          /**
           * Gets the metadata of the revision.
           *
           * @return the {@link RevisionMetadata} object.
           */
          public RevisionMetadata getMetadata() {
              return metadata;
          }
      
          /**
           * Gets the SHA-256 hash value of the revision.
           * This is equivalent to the hash of the revision metadata and data.
           *
           * @return the byte array representing the hash.
           */
          public byte[] getHash() {
              return hash;
          }
      
          /**
           * Gets the SHA-256 hash value of the data portion of the revision.
           * This is only present if the revision is redacted.
           *
           * @return the byte array representing the hash.
           */
          public byte[] getDataHash() {
              return dataHash;
          }
      
          /**
           * Gets the revision data.
           *
           * @return the revision data.
           */
          public IonStruct getData() {
              return data;
          }
      
          /**
           * Returns true if the revision has been redacted.
           * @return a boolean value representing the redaction status
           * of this revision.
           */
          public Boolean isRedacted() {
              return dataHash != null;
          }
      
          /**
           * Constructs a new {@link QldbRevision} from an {@link IonStruct}.
           *
           * The specified {@link IonStruct} must include the following fields
           *
           * - blockAddress -- a {@link BlockAddress},
           * - metadata -- a {@link RevisionMetadata},
           * - hash -- the revision's hash calculated by QLDB,
           * - dataHash -- the user data's hash calculated by QLDB (only present if revision is redacted),
           * - data -- an {@link IonStruct} containing user data in the document.
           *
           * If any of these fields are missing or are malformed, then throws {@link IllegalArgumentException}.
           *
           * If the document hash calculated from the members of the specified {@link IonStruct} does not match
           * the hash member of the {@link IonStruct} then throws {@link IllegalArgumentException}.
           *
           * @param ionStruct
           *              The {@link IonStruct} that contains a {@link QldbRevision} object.
           * @return the converted {@link QldbRevision} object.
           * @throws IOException if failed to parse parameter {@link IonStruct}.
           */
          public static QldbRevision fromIon(final IonStruct ionStruct) throws IOException {
              try {
                  BlockAddress blockAddress = Constants.MAPPER.readValue(ionStruct.get("blockAddress"), BlockAddress.class);
                  IonBlob revisionHash = (IonBlob) ionStruct.get("hash");
                  IonStruct metadataStruct = (IonStruct) ionStruct.get("metadata");
                  IonStruct data = ionStruct.get("data") == null || ionStruct.get("data").isNullValue() ?
                      null : (IonStruct) ionStruct.get("data");
                  IonBlob dataHash = ionStruct.get("dataHash") == null || ionStruct.get("dataHash").isNullValue() ?
                      null : (IonBlob) ionStruct.get("dataHash");
                  if (revisionHash == null || metadataStruct == null) {
                      throw new IllegalArgumentException("Document is missing required fields");
                  }
                  byte[] dataHashBytes = dataHash != null ? dataHash.getBytes() : QldbIonUtils.hashIonValue(data);
                  verifyRevisionHash(metadataStruct, dataHashBytes, revisionHash.getBytes());
                  RevisionMetadata metadata = RevisionMetadata.fromIon(metadataStruct);
                  return new QldbRevision(
                          blockAddress,
                          metadata,
                          revisionHash.getBytes(),
                          dataHash != null ? dataHash.getBytes() : null,
                          data
                  );
              } catch (ClassCastException e) {
                  log.error("Failed to parse ion document");
                  throw new IllegalArgumentException("Document members are not of the correct type", e);
              }
          }
      
          /**
           * Converts a {@link QldbRevision} object to string.
           *
           * @return the string representation of the {@link QldbRevision} object.
           */
          @Override
          public String toString() {
              return "QldbRevision{" +
                      "blockAddress=" + blockAddress +
                      ", metadata=" + metadata +
                      ", hash=" + Arrays.toString(hash) +
                      ", dataHash=" + Arrays.toString(dataHash) +
                      ", data=" + data +
                      '}';
          }
      
          /**
           * Check whether two {@link QldbRevision} objects are equivalent.
           *
           * @return {@code true} if the two objects are equal, {@code false} otherwise.
           */
          @Override
          public boolean equals(final Object o) {
              if (this == o) {
                  return true;
              }
              if (!(o instanceof QldbRevision)) {
                  return false;
              }
              final QldbRevision that = (QldbRevision) o;
              return Objects.equals(getBlockAddress(), that.getBlockAddress())
                      && Objects.equals(getMetadata(), that.getMetadata())
                      && Arrays.equals(getHash(), that.getHash())
                      && Arrays.equals(getDataHash(), that.getDataHash())
                      && Objects.equals(getData(), that.getData());
          }
      
          /**
           * Create a hash code for the {@link QldbRevision} object.
           *
           * @return the hash code.
           */
          @Override
          public int hashCode() {
              // CHECKSTYLE:OFF - Disabling as we are generating a hashCode of multiple properties.
              int result = Objects.hash(blockAddress, metadata, data);
              // CHECKSTYLE:ON
              result = 31 * result + Arrays.hashCode(hash);
              return result;
          }
      
          /**
           * Throws an IllegalArgumentException if the hash of the revision data and metadata
           * does not match the hash provided by QLDB with the revision.
           */
          public void verifyRevisionHash() {
              // Certain internal-only system revisions only contain a hash which cannot be
              // further computed. However, these system hashes still participate to validate
              // the journal block. User revisions will always contain values for all fields
              // and can therefore have their hash computed.
              if (blockAddress == null && metadata == null && data == null && dataHash == null) {
                  return;
              }
      
              try {
                  IonStruct metadataIon = (IonStruct) Constants.MAPPER.writeValueAsIonValue(metadata);
                  byte[] dataHashBytes = isRedacted() ? dataHash : QldbIonUtils.hashIonValue(data);
                  verifyRevisionHash(metadataIon, dataHashBytes, hash);
              } catch (IOException e) {
                  throw new IllegalArgumentException("Could not encode revision metadata to ion.", e);
              }
          }
      
          private static void verifyRevisionHash(IonStruct metadata, byte[] dataHash, byte[] expectedHash) {
              byte[] metadataHash = QldbIonUtils.hashIonValue(metadata);
              byte[] candidateHash = Verifier.dot(metadataHash, dataHash);
              if (!Arrays.equals(candidateHash, expectedHash)) {
                  throw new IllegalArgumentException("Hash entry of QLDB revision and computed hash "
                          + "of QLDB revision do not match");
              }
          }
      }
      ```

   1. `IonLocalDateDeserializer.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.amazon.ion.Timestamp;
      import com.fasterxml.jackson.core.JsonParser;
      import com.fasterxml.jackson.databind.DeserializationContext;
      import com.fasterxml.jackson.databind.JsonDeserializer;
      
      import java.io.IOException;
      import java.time.LocalDate;
      
      /**
       * Deserializes [java.time.LocalDate] from Ion.
       */
      public class IonLocalDateDeserializer extends JsonDeserializer<LocalDate> {
      
          @Override
          public LocalDate deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {
              return timestampToLocalDate((Timestamp) jp.getEmbeddedObject());
          }
      
          private LocalDate timestampToLocalDate(Timestamp timestamp) {
              return LocalDate.of(timestamp.getYear(), timestamp.getMonth(), timestamp.getDay());
          }
      }
      ```

   1. `IonLocalDateSerializer.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.model;
      
      import com.amazon.ion.Timestamp;
      import com.fasterxml.jackson.core.JsonGenerator;
      import com.fasterxml.jackson.databind.SerializerProvider;
      import com.fasterxml.jackson.databind.ser.std.StdScalarSerializer;
      import com.fasterxml.jackson.dataformat.ion.IonGenerator;
      
      import java.io.IOException;
      import java.time.LocalDate;
      
      /**
       * Serializes [java.time.LocalDate] to Ion.
       */
      public class IonLocalDateSerializer extends StdScalarSerializer<LocalDate> {
      
          public IonLocalDateSerializer() {
              super(LocalDate.class);
          }
      
          @Override
          public void serialize(LocalDate date, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
              Timestamp timestamp = Timestamp.forDay(date.getYear(), date.getMonthValue(), date.getDayOfMonth());
              ((IonGenerator) jsonGenerator).writeValue(timestamp);
          }
      }
      ```

1. Überprüfen Sie die folgende Datei (`SampleData.java`), die Daten darstellt, die Sie in die `vehicle-registration`-Tabellen einfügen.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial.model;
   
   import com.amazon.ion.IonString;
   import com.amazon.ion.IonStruct;
   import com.amazon.ion.IonValue;
   import java.io.IOException;
   import java.math.BigDecimal;
   import java.text.ParseException;
   import java.time.LocalDate;
   import java.time.format.DateTimeFormatter;
   import java.util.ArrayList;
   import java.util.Arrays;
   import java.util.Collections;
   import java.util.List;
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.ConnectToLedger;
   import software.amazon.qldb.tutorial.Constants;
   import software.amazon.qldb.tutorial.qldb.DmlResultDocument;
   import software.amazon.qldb.tutorial.qldb.QldbRevision;
   
   /**
    * Sample domain objects for use throughout this tutorial.
    */
   public final class SampleData {
       public static final DateTimeFormatter DATE_TIME_FORMAT = DateTimeFormatter.ofPattern("yyyy-MM-dd");
   
       public static final List<VehicleRegistration> REGISTRATIONS = Collections.unmodifiableList(Arrays.asList(
               new VehicleRegistration("1N4AL11D75C109151", "LEWISR261LL", "WA", "Seattle",
                       BigDecimal.valueOf(90.25), convertToLocalDate("2017-08-21"), convertToLocalDate("2020-05-11"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("KM8SRDHF6EU074761", "CA762X", "WA", "Kent",
                       BigDecimal.valueOf(130.75), convertToLocalDate("2017-09-14"), convertToLocalDate("2020-06-25"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("3HGGK5G53FM761765", "CD820Z", "WA", "Everett",
                       BigDecimal.valueOf(442.30), convertToLocalDate("2011-03-17"), convertToLocalDate("2021-03-24"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("1HVBBAANXWH544237", "LS477D", "WA", "Tacoma",
                       BigDecimal.valueOf(42.20), convertToLocalDate("2011-10-26"), convertToLocalDate("2023-09-25"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("1C4RJFAG0FC625797", "TH393F", "WA", "Olympia",
                       BigDecimal.valueOf(30.45), convertToLocalDate("2013-09-02"), convertToLocalDate("2024-03-19"),
                       new Owners(new Owner(null), Collections.emptyList()))
       ));
   
       public static final List<Vehicle> VEHICLES = Collections.unmodifiableList(Arrays.asList(
               new Vehicle("1N4AL11D75C109151", "Sedan", 2011,  "Audi", "A5", "Silver"),
               new Vehicle("KM8SRDHF6EU074761", "Sedan", 2015, "Tesla", "Model S", "Blue"),
               new Vehicle("3HGGK5G53FM761765", "Motorcycle", 2011, "Ducati", "Monster 1200", "Yellow"),
               new Vehicle("1HVBBAANXWH544237", "Semi", 2009, "Ford", "F 150", "Black"),
               new Vehicle("1C4RJFAG0FC625797", "Sedan", 2019, "Mercedes", "CLK 350", "White")
       ));
   
       public static final List<Person> PEOPLE = Collections.unmodifiableList(Arrays.asList(
               new Person("Raul", "Lewis", convertToLocalDate("1963-08-19"),
                       "LEWISR261LL", "Driver License",  "1719 University Street, Seattle, WA, 98109"),
               new Person("Brent", "Logan", convertToLocalDate("1967-07-03"),
                       "LOGANB486CG", "Driver License", "43 Stockert Hollow Road, Everett, WA, 98203"),
               new Person("Alexis", "Pena", convertToLocalDate("1974-02-10"),
                       "744 849 301", "SSN", "4058 Melrose Street, Spokane Valley, WA, 99206"),
               new Person("Melvin", "Parker", convertToLocalDate("1976-05-22"),
                       "P626-168-229-765", "Passport", "4362 Ryder Avenue, Seattle, WA, 98101"),
               new Person("Salvatore", "Spencer", convertToLocalDate("1997-11-15"),
                       "S152-780-97-415-0", "Passport", "4450 Honeysuckle Lane, Seattle, WA, 98101")
       ));
   
       public static final List<DriversLicense> LICENSES = Collections.unmodifiableList(Arrays.asList(
               new DriversLicense(null, "LEWISR261LL", "Learner",
                       convertToLocalDate("2016-12-20"), convertToLocalDate("2020-11-15")),
               new DriversLicense(null, "LOGANB486CG", "Probationary",
                       convertToLocalDate("2016-04-06"), convertToLocalDate("2020-11-15")),
               new DriversLicense(null, "744 849 301", "Full",
                       convertToLocalDate("2017-12-06"), convertToLocalDate("2022-10-15")),
               new DriversLicense(null, "P626-168-229-765", "Learner",
                       convertToLocalDate("2017-08-16"), convertToLocalDate("2021-11-15")),
               new DriversLicense(null, "S152-780-97-415-0", "Probationary",
                       convertToLocalDate("2015-08-15"), convertToLocalDate("2021-08-21"))
       ));
   
       private SampleData() { }
   
       /**
        * Converts a date string with the format 'yyyy-MM-dd' into a {@link java.util.Date} object.
        *
        * @param date
        *              The date string to convert.
        * @return {@link java.time.LocalDate} or null if there is a {@link ParseException}
        */
       public static synchronized LocalDate convertToLocalDate(String date) {
           return LocalDate.parse(date, DATE_TIME_FORMAT);
       }
   
       /**
        * Convert the result set into a list of IonValues.
        *
        * @param result
        *              The result set to convert.
        * @return a list of IonValues.
        */
       public static List<IonValue> toIonValues(Result result) {
           final List<IonValue> valueList = new ArrayList<>();
           result.iterator().forEachRemaining(valueList::add);
           return valueList;
       }
   
       /**
        * Get the document ID of a particular document.
        *
        * @param txn
        *              A transaction executor object.
        * @param tableName
        *              Name of the table containing the document.
        * @param identifier
        *              The identifier used to narrow down the search.
        * @param value
        *              Value of the identifier.
        * @return the list of document IDs in the result set.
        */
       public static String getDocumentId(final TransactionExecutor txn, final String tableName,
                                          final String identifier, final String value) {
           try {
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(value));
               final String query = String.format("SELECT metadata.id FROM _ql_committed_%s AS p WHERE p.data.%s = ?",
                       tableName, identifier);
               Result result = txn.execute(query, parameters);
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to retrieve document ID using " + value);
               }
               return getStringValueOfStructField((IonStruct) result.iterator().next(), "id");
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Get the document by ID.
        *
        * @param tableName
        *              Name of the table to insert documents into.
        * @param documentId
        *              The unique ID of a document in the Person table.
        * @return a {@link QldbRevision} object.
        * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
        */
       public static QldbRevision getDocumentById(String tableName, String documentId) {
           try {
               final IonValue ionValue = Constants.MAPPER.writeValueAsIonValue(documentId);
               Result result = ConnectToLedger.getDriver().execute(txn -> {
                   return txn.execute("SELECT c.* FROM _ql_committed_" + tableName + " AS c BY docId "
                                      + "WHERE docId = ?", ionValue);
               });
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to retrieve document by id " + documentId + " in table " + tableName);
               }
               return Constants.MAPPER.readValue(result.iterator().next(), QldbRevision.class);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Return a list of modified document IDs as strings from a DML {@link Result}.
        *
        * @param result
        *              The result set from a DML operation.
        * @return the list of document IDs modified by the operation.
        */
       public static List<String> getDocumentIdsFromDmlResult(final Result result) {
           final List<String> strings = new ArrayList<>();
           result.iterator().forEachRemaining(row -> strings.add(getDocumentIdFromDmlResultDocument(row)));
           return strings;
       }
   
       /**
        * Convert the given DML result row's document ID to string.
        *
        * @param dmlResultDocument
        *              The {@link IonValue} representing the results of a DML operation.
        * @return a string of document ID.
        */
       public static String getDocumentIdFromDmlResultDocument(final IonValue dmlResultDocument) {
           try {
               DmlResultDocument result = Constants.MAPPER.readValue(dmlResultDocument, DmlResultDocument.class);
               return result.getDocumentId();
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Get the String value of a given {@link IonStruct} field name.
        * @param struct the {@link IonStruct} from which to get the value.
        * @param fieldName the name of the field from which to get the value.
        * @return the String value of the field within the given {@link IonStruct}.
        */
       public static String getStringValueOfStructField(final IonStruct struct, final String fieldName) {
           return ((IonString) struct.get(fieldName)).stringValue();
       }
   
       /**
        * Return a copy of the given driver's license with updated person Id.
        *
        * @param oldLicense
        *              The old driver's license to update.
        * @param personId
        *              The PersonId of the driver.
        * @return the updated {@link DriversLicense}.
        */
       public static DriversLicense updatePersonIdDriversLicense(final DriversLicense oldLicense, final String personId) {
           return new DriversLicense(personId, oldLicense.getLicenseNumber(), oldLicense.getLicenseType(),
                   oldLicense.getValidFromDate(), oldLicense.getValidToDate());
       }
   
       /**
        * Return a copy of the given vehicle registration with updated person Id.
        *
        * @param oldRegistration
        *              The old vehicle registration to update.
        * @param personId
        *              The PersonId of the driver.
        * @return the updated {@link VehicleRegistration}.
        */
       public static VehicleRegistration updateOwnerVehicleRegistration(final VehicleRegistration oldRegistration,
                                                                        final String personId) {
           return new VehicleRegistration(oldRegistration.getVin(), oldRegistration.getLicensePlateNumber(),
                   oldRegistration.getState(), oldRegistration.getCity(), oldRegistration.getPendingPenaltyTicketAmount(),
                   oldRegistration.getValidFromDate(), oldRegistration.getValidToDate(),
                   new Owners(new Owner(personId), Collections.emptyList()));
       }
   }
   ```

------
#### [ 1.x ]

**Wichtig**  
Für das Amazon Ion-Paket müssen Sie den Namespace `com.amazon.ion` in Ihrer Anwendung verwenden. Das AWS SDK für Java hängt von einem anderen Ion-Paket unter dem Namespace ab`software.amazon.ion`, aber das ist ein Legacy-Paket, das nicht mit dem QLDB-Treiber kompatibel ist.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial.model;
   
   import com.amazon.ion.IonString;
   import com.amazon.ion.IonStruct;
   import com.amazon.ion.IonValue;
   import software.amazon.qldb.QldbSession;
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.Constants;
   import software.amazon.qldb.tutorial.qldb.DmlResultDocument;
   import software.amazon.qldb.tutorial.qldb.QldbRevision;
   
   import java.io.IOException;
   
   import java.math.BigDecimal;
   import java.text.ParseException;
   import java.time.LocalDate;
   import java.time.format.DateTimeFormatter;
   import java.util.ArrayList;
   import java.util.Arrays;
   import java.util.Collections;
   import java.util.List;
   
   /**
    * Sample domain objects for use throughout this tutorial.
    */
   public final class SampleData {
       public static final DateTimeFormatter DATE_TIME_FORMAT = DateTimeFormatter.ofPattern("yyyy-MM-dd");
   
       public static final List<VehicleRegistration> REGISTRATIONS = Collections.unmodifiableList(Arrays.asList(
               new VehicleRegistration("1N4AL11D75C109151", "LEWISR261LL", "WA", "Seattle",
                       BigDecimal.valueOf(90.25), convertToLocalDate("2017-08-21"), convertToLocalDate("2020-05-11"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("KM8SRDHF6EU074761", "CA762X", "WA", "Kent",
                       BigDecimal.valueOf(130.75), convertToLocalDate("2017-09-14"), convertToLocalDate("2020-06-25"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("3HGGK5G53FM761765", "CD820Z", "WA", "Everett",
                       BigDecimal.valueOf(442.30), convertToLocalDate("2011-03-17"), convertToLocalDate("2021-03-24"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("1HVBBAANXWH544237", "LS477D", "WA", "Tacoma",
                       BigDecimal.valueOf(42.20), convertToLocalDate("2011-10-26"), convertToLocalDate("2023-09-25"),
                       new Owners(new Owner(null), Collections.emptyList())),
               new VehicleRegistration("1C4RJFAG0FC625797", "TH393F", "WA", "Olympia",
                       BigDecimal.valueOf(30.45), convertToLocalDate("2013-09-02"), convertToLocalDate("2024-03-19"),
                       new Owners(new Owner(null), Collections.emptyList()))
       ));
   
       public static final List<Vehicle> VEHICLES = Collections.unmodifiableList(Arrays.asList(
               new Vehicle("1N4AL11D75C109151", "Sedan", 2011,  "Audi", "A5", "Silver"),
               new Vehicle("KM8SRDHF6EU074761", "Sedan", 2015, "Tesla", "Model S", "Blue"),
               new Vehicle("3HGGK5G53FM761765", "Motorcycle", 2011, "Ducati", "Monster 1200", "Yellow"),
               new Vehicle("1HVBBAANXWH544237", "Semi", 2009, "Ford", "F 150", "Black"),
               new Vehicle("1C4RJFAG0FC625797", "Sedan", 2019, "Mercedes", "CLK 350", "White")
       ));
   
       public static final List<Person> PEOPLE = Collections.unmodifiableList(Arrays.asList(
               new Person("Raul", "Lewis", convertToLocalDate("1963-08-19"),
                       "LEWISR261LL", "Driver License",  "1719 University Street, Seattle, WA, 98109"),
               new Person("Brent", "Logan", convertToLocalDate("1967-07-03"),
                       "LOGANB486CG", "Driver License", "43 Stockert Hollow Road, Everett, WA, 98203"),
               new Person("Alexis", "Pena", convertToLocalDate("1974-02-10"),
                       "744 849 301", "SSN", "4058 Melrose Street, Spokane Valley, WA, 99206"),
               new Person("Melvin", "Parker", convertToLocalDate("1976-05-22"),
                       "P626-168-229-765", "Passport", "4362 Ryder Avenue, Seattle, WA, 98101"),
               new Person("Salvatore", "Spencer", convertToLocalDate("1997-11-15"),
                       "S152-780-97-415-0", "Passport", "4450 Honeysuckle Lane, Seattle, WA, 98101")
       ));
   
       public static final List<DriversLicense> LICENSES = Collections.unmodifiableList(Arrays.asList(
               new DriversLicense(null, "LEWISR261LL", "Learner",
                       convertToLocalDate("2016-12-20"), convertToLocalDate("2020-11-15")),
               new DriversLicense(null, "LOGANB486CG", "Probationary",
                       convertToLocalDate("2016-04-06"), convertToLocalDate("2020-11-15")),
               new DriversLicense(null, "744 849 301", "Full",
                       convertToLocalDate("2017-12-06"), convertToLocalDate("2022-10-15")),
               new DriversLicense(null, "P626-168-229-765", "Learner",
                       convertToLocalDate("2017-08-16"), convertToLocalDate("2021-11-15")),
               new DriversLicense(null, "S152-780-97-415-0", "Probationary",
                       convertToLocalDate("2015-08-15"), convertToLocalDate("2021-08-21"))
       ));
   
       private SampleData() { }
   
       /**
        * Converts a date string with the format 'yyyy-MM-dd' into a {@link java.util.Date} object.
        *
        * @param date
        *              The date string to convert.
        * @return {@link LocalDate} or null if there is a {@link ParseException}
        */
       public static synchronized LocalDate convertToLocalDate(String date) {
           return LocalDate.parse(date, DATE_TIME_FORMAT);
       }
   
       /**
        * Convert the result set into a list of IonValues.
        *
        * @param result
        *              The result set to convert.
        * @return a list of IonValues.
        */
       public static List<IonValue> toIonValues(Result result) {
           final List<IonValue> valueList = new ArrayList<>();
           result.iterator().forEachRemaining(valueList::add);
           return valueList;
       }
   
       /**
        * Get the document ID of a particular document.
        *
        * @param txn
        *              A transaction executor object.
        * @param tableName
        *              Name of the table containing the document.
        * @param identifier
        *              The identifier used to narrow down the search.
        * @param value
        *              Value of the identifier.
        * @return the list of document IDs in the result set.
        */
       public static String getDocumentId(final TransactionExecutor txn, final String tableName,
                                          final String identifier, final String value) {
           try {
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(value));
               final String query = String.format("SELECT metadata.id FROM _ql_committed_%s AS p WHERE p.data.%s = ?",
                       tableName, identifier);
               Result result = txn.execute(query, parameters);
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to retrieve document ID using " + value);
               }
               return getStringValueOfStructField((IonStruct) result.iterator().next(), "id");
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Get the document by ID.
        *
        * @param qldbSession
        *              A QLDB session.
        * @param tableName
        *              Name of the table to insert documents into.
        * @param documentId
        *              The unique ID of a document in the Person table.
        * @return a {@link QldbRevision} object.
        * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
        */
       public static QldbRevision getDocumentById(QldbSession qldbSession, String tableName, String documentId) {
           try {
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(documentId));
               final String query = String.format("SELECT c.* FROM _ql_committed_%s AS c BY docId WHERE docId = ?", tableName);
               Result result = qldbSession.execute(query, parameters);
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to retrieve document by id " + documentId + " in table " + tableName);
               }
               return Constants.MAPPER.readValue(result.iterator().next(), QldbRevision.class);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Return a list of modified document IDs as strings from a DML {@link Result}.
        *
        * @param result
        *              The result set from a DML operation.
        * @return the list of document IDs modified by the operation.
        */
       public static List<String> getDocumentIdsFromDmlResult(final Result result) {
           final List<String> strings = new ArrayList<>();
           result.iterator().forEachRemaining(row -> strings.add(getDocumentIdFromDmlResultDocument(row)));
           return strings;
       }
   
       /**
        * Convert the given DML result row's document ID to string.
        *
        * @param dmlResultDocument
        *              The {@link IonValue} representing the results of a DML operation.
        * @return a string of document ID.
        */
       public static String getDocumentIdFromDmlResultDocument(final IonValue dmlResultDocument) {
           try {
               DmlResultDocument result = Constants.MAPPER.readValue(dmlResultDocument, DmlResultDocument.class);
               return result.getDocumentId();
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Get the String value of a given {@link IonStruct} field name.
        * @param struct the {@link IonStruct} from which to get the value.
        * @param fieldName the name of the field from which to get the value.
        * @return the String value of the field within the given {@link IonStruct}.
        */
       public static String getStringValueOfStructField(final IonStruct struct, final String fieldName) {
           return ((IonString) struct.get(fieldName)).stringValue();
       }
   
       /**
        * Return a copy of the given driver's license with updated person Id.
        *
        * @param oldLicense
        *              The old driver's license to update.
        * @param personId
        *              The PersonId of the driver.
        * @return the updated {@link DriversLicense}.
        */
       public static DriversLicense updatePersonIdDriversLicense(final DriversLicense oldLicense, final String personId) {
           return new DriversLicense(personId, oldLicense.getLicenseNumber(), oldLicense.getLicenseType(),
                   oldLicense.getValidFromDate(), oldLicense.getValidToDate());
       }
   
       /**
        * Return a copy of the given vehicle registration with updated person Id.
        *
        * @param oldRegistration
        *              The old vehicle registration to update.
        * @param personId
        *              The PersonId of the driver.
        * @return the updated {@link VehicleRegistration}.
        */
       public static VehicleRegistration updateOwnerVehicleRegistration(final VehicleRegistration oldRegistration,
                                                                        final String personId) {
           return new VehicleRegistration(oldRegistration.getVin(), oldRegistration.getLicensePlateNumber(),
                   oldRegistration.getState(), oldRegistration.getCity(), oldRegistration.getPendingPenaltyTicketAmount(),
                   oldRegistration.getValidFromDate(), oldRegistration.getValidToDate(),
                   new Owners(new Owner(personId), Collections.emptyList()));
       }
   }
   ```

------
**Anmerkung**  
Diese Klasse verwendet Ion-Bibliotheken, um Hilfsmethoden bereitzustellen, die Ihre Daten in das und aus dem Ion-Format konvertieren.
Die `getDocumentId`-Methode führt eine Abfrage für eine Tabelle mit dem Präfix `_ql_committed_` aus. Dies ist ein reserviertes Präfix, das angibt, dass Sie die *bestätigte Ansicht* einer Tabelle abfragen möchten. In dieser Ansicht sind Ihre Daten im `data`-Feld verschachtelt und Metadaten sind im `metadata`-Feld verschachtelt.

1. Kompilieren Sie das folgende Programm (`CreateTable.java`) und führen Sie es aus, um die zuvor genannten Tabellen zu erstellen.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Create tables in a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class CreateTable {
       public static final Logger log = LoggerFactory.getLogger(CreateTable.class);
   
       private CreateTable() { }
   
       /**
        * Registrations, vehicles, owners, and licenses tables being created in a single transaction.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param tableName
        *              Name of the table to be created.
        * @return the number of tables created.
        */
       public static int createTable(final TransactionExecutor txn, final String tableName) {
           log.info("Creating the '{}' table...", tableName);
           final String createTable = String.format("CREATE TABLE %s", tableName);
           final Result result = txn.execute(createTable);
           log.info("{} table created successfully.", tableName);
           return SampleData.toIonValues(result).size();
       }
   
       public static void main(final String... args) {
           ConnectToLedger.getDriver().execute(txn -> {
               createTable(txn, Constants.DRIVERS_LICENSE_TABLE_NAME);
               createTable(txn, Constants.PERSON_TABLE_NAME);
               createTable(txn, Constants.VEHICLE_TABLE_NAME);
               createTable(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME);
           });
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Create tables in a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class CreateTable {
       public static final Logger log = LoggerFactory.getLogger(CreateTable.class);
   
       private CreateTable() { }
   
       /**
        * Registrations, vehicles, owners, and licenses tables being created in a single transaction.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param tableName
        *              Name of the table to be created.
        * @return the number of tables created.
        */
       public static int createTable(final TransactionExecutor txn, final String tableName) {
           log.info("Creating the '{}' table...", tableName);
           final String createTable = String.format("CREATE TABLE %s", tableName);
           final Result result = txn.execute(createTable);
           log.info("{} table created successfully.", tableName);
           return SampleData.toIonValues(result).size();
       }
   
       public static void main(final String... args) {
           ConnectToLedger.getDriver().execute(txn -> {
               createTable(txn, Constants.DRIVERS_LICENSE_TABLE_NAME);
               createTable(txn, Constants.PERSON_TABLE_NAME);
               createTable(txn, Constants.VEHICLE_TABLE_NAME);
               createTable(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME);
           }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
       }
   }
   ```

------
**Anmerkung**  
Dieses Programm verdeutlicht, wie ein `TransactionExecutor`-Lambda an die `execute`-Methode übergeben wird. In diesem Beispiel führen Sie mehrere `CREATE TABLE` PartiQL-Anweisungen in einer einzigen Transaktion aus, indem Sie einen Lambda-Ausdruck verwenden.  
Die `execute` Methode startet implizit eine Transaktion, führt alle Anweisungen im Lambda aus und schreibt dann die Transaktion automatisch fest.

1. Kompilieren Sie das folgende Programm (`CreateIndex.java`) und führen Sie es aus, um wie zuvor beschrieben Indizes für die Tabellen zu erstellen.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Create indexes on tables in a particular ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class CreateIndex {
       public static final Logger log = LoggerFactory.getLogger(CreateIndex.class);
   
       private CreateIndex() { }
   
       /**
        * In this example, create indexes for registrations and vehicles tables.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param tableName
        *              Name of the table to be created.
        * @param indexAttribute
        *              The index attribute to use.
        * @return the number of tables created.
        */
       public static int createIndex(final TransactionExecutor txn, final String tableName, final String indexAttribute) {
           log.info("Creating an index on {}...", indexAttribute);
           final String createIndex = String.format("CREATE INDEX ON %s (%s)", tableName, indexAttribute);
           final Result r = txn.execute(createIndex);
           return SampleData.toIonValues(r).size();
       }
   
       public static void main(final String... args) {
           ConnectToLedger.getDriver().execute(txn -> {
               createIndex(txn, Constants.PERSON_TABLE_NAME, Constants.PERSON_GOV_ID_INDEX_NAME);
               createIndex(txn, Constants.VEHICLE_TABLE_NAME, Constants.VIN_INDEX_NAME);
               createIndex(txn, Constants.DRIVERS_LICENSE_TABLE_NAME, Constants.DRIVER_LICENSE_NUMBER_INDEX_NAME);
               createIndex(txn, Constants.DRIVERS_LICENSE_TABLE_NAME, Constants.DRIVER_LICENSE_PERSONID_INDEX_NAME);
               createIndex(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME, Constants.VIN_INDEX_NAME);
               createIndex(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME,
                       Constants.VEHICLE_REGISTRATION_LICENSE_PLATE_NUMBER_INDEX_NAME);
           });
           log.info("Indexes created successfully!");
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Create indexes on tables in a particular ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class CreateIndex {
       public static final Logger log = LoggerFactory.getLogger(CreateIndex.class);
   
       private CreateIndex() { }
   
       /**
        * In this example, create indexes for registrations and vehicles tables.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param tableName
        *              Name of the table to be created.
        * @param indexAttribute
        *              The index attribute to use.
        * @return the number of tables created.
        */
       public static int createIndex(final TransactionExecutor txn, final String tableName, final String indexAttribute) {
           log.info("Creating an index on {}...", indexAttribute);
           final String createIndex = String.format("CREATE INDEX ON %s (%s)", tableName, indexAttribute);
           final Result r = txn.execute(createIndex);
           return SampleData.toIonValues(r).size();
       }
   
       public static void main(final String... args) {
           ConnectToLedger.getDriver().execute(txn -> {
               createIndex(txn, Constants.PERSON_TABLE_NAME, Constants.PERSON_GOV_ID_INDEX_NAME);
               createIndex(txn, Constants.VEHICLE_TABLE_NAME, Constants.VIN_INDEX_NAME);
               createIndex(txn, Constants.DRIVERS_LICENSE_TABLE_NAME, Constants.DRIVER_LICENSE_NUMBER_INDEX_NAME);
               createIndex(txn, Constants.DRIVERS_LICENSE_TABLE_NAME, Constants.DRIVER_LICENSE_PERSONID_INDEX_NAME);
               createIndex(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME, Constants.VIN_INDEX_NAME);
               createIndex(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME,
                       Constants.VEHICLE_REGISTRATION_LICENSE_PLATE_NUMBER_INDEX_NAME);
           }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
           log.info("Indexes created successfully!");
       }
   }
   ```

------

1. Kompilieren Sie das folgende Programm (`InsertDocument.java`) und führen Sie es aus, um die Beispieldaten in Ihre Tabellen einzufügen.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.List;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import com.amazon.ion.IonValue;
   
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.DriversLicense;
   import software.amazon.qldb.tutorial.model.SampleData;
   import software.amazon.qldb.tutorial.model.VehicleRegistration;
   
   /**
    * Insert documents into a table in a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class InsertDocument {
       public static final Logger log = LoggerFactory.getLogger(InsertDocument.class);
   
       private InsertDocument() { }
   
       /**
        * Insert the given list of documents into the specified table and return the document IDs of the inserted documents.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param tableName
        *              Name of the table to insert documents into.
        * @param documents
        *              List of documents to insert into the specified table.
        * @return a list of document IDs.
        * @throws IllegalStateException if failed to convert documents into an {@link IonValue}.
        */
       public static List<String> insertDocuments(final TransactionExecutor txn, final String tableName,
                                                  final List documents) {
           log.info("Inserting some documents in the {} table...", tableName);
           try {
               final String query = String.format("INSERT INTO %s ?", tableName);
               final IonValue ionDocuments = Constants.MAPPER.writeValueAsIonValue(documents);
   
               return SampleData.getDocumentIdsFromDmlResult(txn.execute(query, ionDocuments));
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Update PersonIds in driver's licenses and in vehicle registrations using document IDs.
        *
        * @param documentIds
        *              List of document IDs representing the PersonIds in DriversLicense and PrimaryOwners in VehicleRegistration.
        * @param licenses
        *              List of driver's licenses to update.
        * @param registrations
        *              List of registrations to update.
        */
       public static void updatePersonId(final List<String> documentIds, final List<DriversLicense> licenses,
                                         final List<VehicleRegistration> registrations) {
           for (int i = 0; i < documentIds.size(); ++i) {
               DriversLicense license = SampleData.LICENSES.get(i);
               VehicleRegistration registration = SampleData.REGISTRATIONS.get(i);
               licenses.add(SampleData.updatePersonIdDriversLicense(license, documentIds.get(i)));
               registrations.add(SampleData.updateOwnerVehicleRegistration(registration, documentIds.get(i)));
           }
       }
   
       public static void main(final String... args) {
           final List<DriversLicense> newDriversLicenses = new ArrayList<>();
           final List<VehicleRegistration> newVehicleRegistrations = new ArrayList<>();
           ConnectToLedger.getDriver().execute(txn -> {
               List<String> documentIds = insertDocuments(txn, Constants.PERSON_TABLE_NAME, SampleData.PEOPLE);
               updatePersonId(documentIds, newDriversLicenses, newVehicleRegistrations);
               insertDocuments(txn, Constants.VEHICLE_TABLE_NAME, SampleData.VEHICLES);
               insertDocuments(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME,
                       Collections.unmodifiableList(newVehicleRegistrations));
               insertDocuments(txn, Constants.DRIVERS_LICENSE_TABLE_NAME,
                       Collections.unmodifiableList(newDriversLicenses));
           });
           log.info("Documents inserted successfully!");
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonValue;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.QldbSession;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.DriversLicense;
   import software.amazon.qldb.tutorial.model.SampleData;
   import software.amazon.qldb.tutorial.model.VehicleRegistration;
   
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.List;
   
   /**
    * Insert documents into a table in a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class InsertDocument {
       public static final Logger log = LoggerFactory.getLogger(InsertDocument.class);
   
       private InsertDocument() { }
   
       /**
        * Insert the given list of documents into the specified table and return the document IDs of the inserted documents.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param tableName
        *              Name of the table to insert documents into.
        * @param documents
        *              List of documents to insert into the specified table.
        * @return a list of document IDs.
        * @throws IllegalStateException if failed to convert documents into an {@link IonValue}.
        */
       public static List<String> insertDocuments(final TransactionExecutor txn, final String tableName,
                                                  final List documents) {
           log.info("Inserting some documents in the {} table...", tableName);
           try {
               final String statement = String.format("INSERT INTO %s ?", tableName);
               final IonValue ionDocuments = Constants.MAPPER.writeValueAsIonValue(documents);
               final List<IonValue> parameters = Collections.singletonList(ionDocuments);
               return SampleData.getDocumentIdsFromDmlResult(txn.execute(statement, parameters));
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Update PersonIds in driver's licenses and in vehicle registrations using document IDs.
        *
        * @param documentIds
        *              List of document IDs representing the PersonIds in DriversLicense and PrimaryOwners in VehicleRegistration.
        * @param licenses
        *              List of driver's licenses to update.
        * @param registrations
        *              List of registrations to update.
        */
       public static void updatePersonId(final List<String> documentIds, final List<DriversLicense> licenses,
                                         final List<VehicleRegistration> registrations) {
           for (int i = 0; i < documentIds.size(); ++i) {
               DriversLicense license = SampleData.LICENSES.get(i);
               VehicleRegistration registration = SampleData.REGISTRATIONS.get(i);
               licenses.add(SampleData.updatePersonIdDriversLicense(license, documentIds.get(i)));
               registrations.add(SampleData.updateOwnerVehicleRegistration(registration, documentIds.get(i)));
           }
       }
   
       public static void main(final String... args) {
           final List<DriversLicense> newDriversLicenses = new ArrayList<>();
           final List<VehicleRegistration> newVehicleRegistrations = new ArrayList<>();
           ConnectToLedger.getDriver().execute(txn -> {
               List<String> documentIds = insertDocuments(txn, Constants.PERSON_TABLE_NAME, SampleData.PEOPLE);
               updatePersonId(documentIds, newDriversLicenses, newVehicleRegistrations);
               insertDocuments(txn, Constants.VEHICLE_TABLE_NAME, SampleData.VEHICLES);
               insertDocuments(txn, Constants.VEHICLE_REGISTRATION_TABLE_NAME,
                       Collections.unmodifiableList(newVehicleRegistrations));
               insertDocuments(txn, Constants.DRIVERS_LICENSE_TABLE_NAME,
                       Collections.unmodifiableList(newDriversLicenses));
           }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
           log.info("Documents inserted successfully!");
       }
   }
   ```

------
**Anmerkung**  
Dieses Programm veranschaulicht, wie die `execute`-Methode mit parametrisierten Werten aufgerufen wird. Sie können außerdem eine Liste mit Datenparametern des Typs `IonValue` an die auszuführende PartiQL-Anweisung übergeben. Verwenden Sie ein Fragezeichen (`?`) als Variablenplatzhalter in Ihrer Anweisungszeichenfolge.
Wenn eine `INSERT`-Anweisung erfolgreich ist, wird die `id` jedes eingefügten Dokuments zurückgegeben.

Als Nächstes können Sie mit `SELECT`-Anweisungen Daten aus den Tabellen im `vehicle-registration`-Ledger lesen. Fahren Sie mit [Schritt 4: Fragen Sie die Tabellen in einem Hauptbuch ab](getting-started.java.step-4.md) fort.

# Schritt 4: Fragen Sie die Tabellen in einem Hauptbuch ab
<a name="getting-started.java.step-4"></a>

**Wichtig**  
Hinweis zum Ende des Supports: Bestandskunden können Amazon QLDB bis zum Ende des Supports am 31.07.2025 nutzen. Weitere Informationen finden Sie unter [Migrieren eines Amazon QLDB-Ledgers zu Amazon](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/) Aurora PostgreSQL.

Nachdem Sie Tabellen in einem Amazon QLDB-Ledger erstellt und mit Daten geladen haben, können Sie Abfragen ausführen, um die gerade eingefügten Fahrzeugregistrierungsdaten zu überprüfen. QLDB verwendet [PartiQL](ql-reference.md) als Abfragesprache und [Amazon Ion](ion.md) als dokumentenorientiertes Datenmodell.

PartiQL ist eine SQL-kompatible Open-Source-Abfragesprache, die für die Verwendung mit Ion erweitert wurde. Mit PartiSQL können Sie Ihre Daten mit vertrauten SQL-Operatoren einfügen, abfragen und verwalten. Amazon Ion ist eine Obermenge von JSON. Ion ist ein dokumentenbasiertes Open-Source-Datenformat, das Ihnen die Flexibilität bietet, strukturierte, halbstrukturierte und verschachtelte Daten zu speichern und zu verarbeiten.

In diesem Schritt verwenden Sie `SELECT`-Anweisungen zum Lesen von Daten aus den Tabellen im `vehicle-registration`-Ledger.

**Warnung**  
Wenn Sie eine Abfrage in QLDB ohne indizierte Suche ausführen, wird ein vollständiger Tabellenscan aufgerufen. PartiQL unterstützt solche Abfragen, weil es SQL-kompatibel ist. Führen *Sie jedoch keine* Tabellenscans für Produktionsanwendungsfälle in QLDB aus. Tabellenscans können bei großen Tabellen zu Leistungsproblemen führen, einschließlich Parallelitätskonflikten und Transaktions-Timeouts.  
Um Tabellenscans zu vermeiden, müssen Sie Anweisungen mit einer `WHERE` Prädikatklausel ausführen, indem Sie einen *Gleichheitsoperator* für ein indiziertes Feld oder eine Dokument-ID verwenden, z. B. oder. `WHERE indexedField = 123` `WHERE indexedField IN (456, 789)` Weitere Informationen finden Sie unter [Optimieren der Abfrageleistung](working.optimize.md).

**So fragen Sie die Tabellen ab**
+ Kompilieren Sie das folgende Programm (`FindVehicles.java`) und führen Sie es aus, um alle Fahrzeuge abzufragen, die unter einer Person in Ihrem Ledger registriert sind.

------
#### [ 2.x ]

  ```
  /*
   * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   * SPDX-License-Identifier: MIT-0
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy of this
   * software and associated documentation files (the "Software"), to deal in the Software
   * without restriction, including without limitation the rights to use, copy, modify,
   * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  package software.amazon.qldb.tutorial;
  
  import java.io.IOException;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.amazon.ion.IonValue;
  
  import software.amazon.qldb.Result;
  import software.amazon.qldb.TransactionExecutor;
  import software.amazon.qldb.tutorial.model.Person;
  import software.amazon.qldb.tutorial.model.SampleData;
  
  /**
   * Find all vehicles registered under a person.
   *
   * This code expects that you have AWS credentials setup per:
   * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
   */
  public final class FindVehicles {
      public static final Logger log = LoggerFactory.getLogger(FindVehicles.class);
  
      private FindVehicles() { }
  
      /**
       * Find vehicles registered under a driver using their government ID.
       *
       * @param txn
       *              The {@link TransactionExecutor} for lambda execute.
       * @param govId
       *              The government ID of the owner.
       * @throws IllegalStateException if failed to convert parameters into {@link IonValue}.
       */
      public static void findVehiclesForOwner(final TransactionExecutor txn, final String govId) {
          try {
              final String documentId = Person.getDocumentIdByGovId(txn, govId);
              final String query = "SELECT v FROM Vehicle AS v INNER JOIN VehicleRegistration AS r "
                      + "ON v.VIN = r.VIN WHERE r.Owners.PrimaryOwner.PersonId = ?";
  
              final Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(documentId));
              log.info("List of Vehicles for owner with GovId: {}...", govId);
              ScanTable.printDocuments(result);
          } catch (IOException ioe) {
              throw new IllegalStateException(ioe);
          }
      }
  
      public static void main(final String... args) {
          final Person person = SampleData.PEOPLE.get(0);
          ConnectToLedger.getDriver().execute(txn -> {
              findVehiclesForOwner(txn, person.getGovId());
          });
      }
  }
  ```

------
#### [ 1.x ]

  ```
  /*
   * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
   * SPDX-License-Identifier: MIT-0
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy of this
   * software and associated documentation files (the "Software"), to deal in the Software
   * without restriction, including without limitation the rights to use, copy, modify,
   * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  package software.amazon.qldb.tutorial;
  
  import java.io.IOException;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.amazon.ion.IonValue;
  
  import software.amazon.qldb.Result;
  import software.amazon.qldb.TransactionExecutor;
  import software.amazon.qldb.tutorial.model.Person;
  import software.amazon.qldb.tutorial.model.SampleData;
  
  /**
   * Find all vehicles registered under a person.
   *
   * This code expects that you have AWS credentials setup per:
   * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
   */
  public final class FindVehicles {
      public static final Logger log = LoggerFactory.getLogger(FindVehicles.class);
  
      private FindVehicles() { }
  
      /**
       * Find vehicles registered under a driver using their government ID.
       *
       * @param txn
       *              The {@link TransactionExecutor} for lambda execute.
       * @param govId
       *              The government ID of the owner.
       * @throws IllegalStateException if failed to convert parameters into {@link IonValue}.
       */
      public static void findVehiclesForOwner(final TransactionExecutor txn, final String govId) {
          try {
              final String documentId = Person.getDocumentIdByGovId(txn, govId);
              final String query = "SELECT v FROM Vehicle AS v INNER JOIN VehicleRegistration AS r "
                      + "ON v.VIN = r.VIN WHERE r.Owners.PrimaryOwner.PersonId = ?";
  
              final Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(documentId));
              log.info("List of Vehicles for owner with GovId: {}...", govId);
              ScanTable.printDocuments(result);
          } catch (IOException ioe) {
              throw new IllegalStateException(ioe);
          }
      }
  
      public static void main(final String... args) {
          final Person person = SampleData.PEOPLE.get(0);
          ConnectToLedger.getDriver().execute(txn -> {
              findVehiclesForOwner(txn, person.getGovId());
          }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
      }
  }
  ```

------
**Anmerkung**  
Zunächst fragt dieses Programm die `Person`-Tabelle nach dem Dokument mit `GovId LEWISR261LL` ab, um sein `id`-Metadatenfeld abzurufen.  
Anschließend verwendet es dieses Dokument `id` als Fremdschlüssel, um die `VehicleRegistration`-Tabelle nach `PrimaryOwner.PersonId` abzufragen. Es tritt führt außerdem `VehicleRegistration` mit der `Vehicle`-Tabelle im `VIN`-Feld zusammen.

Weitere Informationen zum Ändern von Dokumenten in den Tabellen im `vehicle-registration`-Ledger finden Sie unter [Schritt 5: Dokumente in einem Ledger ändern](getting-started.java.step-5.md).

# Schritt 5: Dokumente in einem Ledger ändern
<a name="getting-started.java.step-5"></a>

**Wichtig**  
Hinweis zum Ende des Supports: Bestandskunden können Amazon QLDB bis zum Ende des Supports am 31.07.2025 nutzen. Weitere Informationen finden Sie unter [Migrieren eines Amazon QLDB-Ledgers zu Amazon](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/) Aurora PostgreSQL.

Da Sie nun über Daten verfügen, mit denen Sie arbeiten können, können Sie damit beginnen, Änderungen an Dokumenten im `vehicle-registration` Hauptbuch in Amazon QLDB vorzunehmen. In diesem Schritt verdeutlichen die folgenden Codebeispiele, wie Sie Data Manipulation Language (DML)-Anweisungen ausführen. Diese Anweisungen aktualisieren den primären Eigentümer eines Fahrzeugs und fügen einem anderen Fahrzeug einen sekundären Eigentümer hinzu.

**So ändern Sie Dokumente**

1. Kompilieren Sie das folgende Programm (`TransferVehicleOwnership.java`) und führen Sie es aus, um den primären Eigentümer eines Fahrzeugs in Ihrem Ledger mit VIN `1N4AL11D75C109151` zu aktualisieren.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonReader;
   import com.amazon.ion.IonStruct;
   import com.amazon.ion.IonValue;
   import com.amazon.ion.system.IonReaderBuilder;
   
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.LinkedHashMap;
   import java.util.List;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.Owner;
   import software.amazon.qldb.tutorial.model.Person;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Find primary owner for a particular vehicle's VIN.
    * Transfer to another primary owner for a particular vehicle's VIN.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class TransferVehicleOwnership {
       public static final Logger log = LoggerFactory.getLogger(TransferVehicleOwnership.class);
   
       private TransferVehicleOwnership() { }
   
       /**
        * Query a driver's information using the given ID.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param documentId
        *              The unique ID of a document in the Person table.
        * @return a {@link Person} object.
        * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
        */
       public static Person findPersonFromDocumentId(final TransactionExecutor txn, final String documentId) {
           try {
               log.info("Finding person for documentId: {}...", documentId);
               final String query = "SELECT p.* FROM Person AS p BY pid WHERE pid = ?";
   
               Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(documentId));
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to find person with ID: " + documentId);
               }
   
               return Constants.MAPPER.readValue(result.iterator().next(), Person.class);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Find the primary owner for the given VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @return a {@link Person} object.
        * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
        */
       public static Person findPrimaryOwnerForVehicle(final TransactionExecutor txn, final String vin) {
           try {
               log.info("Finding primary owner for vehicle with Vin: {}...", vin);
               final String query = "SELECT Owners.PrimaryOwner.PersonId FROM VehicleRegistration AS v WHERE v.VIN = ?";
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
               Result result = txn.execute(query, parameters);
               final List<IonStruct> documents = ScanTable.toIonStructs(result);
               ScanTable.printDocuments(documents);
               if (documents.isEmpty()) {
                   throw new IllegalStateException("Unable to find registrations with VIN: " + vin);
               }
   
               final IonReader reader = IonReaderBuilder.standard().build(documents.get(0));
               final String personId = Constants.MAPPER.readValue(reader, LinkedHashMap.class).get("PersonId").toString();
               return findPersonFromDocumentId(txn, personId);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Update the primary owner for a vehicle registration with the given documentId.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @param documentId
        *              New PersonId for the primary owner.
        * @throws IllegalStateException if no vehicle registration was found using the given document ID and VIN, or if failed
        * to convert parameters into {@link IonValue}.
        */
       public static void updateVehicleRegistration(final TransactionExecutor txn, final String vin, final String documentId) {
           try {
               log.info("Updating primary owner for vehicle with Vin: {}...", vin);
               final String query = "UPDATE VehicleRegistration AS v SET v.Owners.PrimaryOwner = ? WHERE v.VIN = ?";
   
               final List<IonValue> parameters = new ArrayList<>();
               parameters.add(Constants.MAPPER.writeValueAsIonValue(new Owner(documentId)));
               parameters.add(Constants.MAPPER.writeValueAsIonValue(vin));
   
               Result result = txn.execute(query, parameters);
               ScanTable.printDocuments(result);
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to transfer vehicle, could not find registration.");
               } else {
                   log.info("Successfully transferred vehicle with VIN '{}' to new owner.", vin);
               }
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       public static void main(final String... args) {
           final String vin = SampleData.VEHICLES.get(0).getVin();
           final String primaryOwnerGovId = SampleData.PEOPLE.get(0).getGovId();
           final String newPrimaryOwnerGovId = SampleData.PEOPLE.get(1).getGovId();
   
           ConnectToLedger.getDriver().execute(txn -> {
               final Person primaryOwner = findPrimaryOwnerForVehicle(txn, vin);
               if (!primaryOwner.getGovId().equals(primaryOwnerGovId)) {
                   // Verify the primary owner.
                   throw new IllegalStateException("Incorrect primary owner identified for vehicle, unable to transfer.");
               }
   
               final String newOwner = Person.getDocumentIdByGovId(txn, newPrimaryOwnerGovId);
               updateVehicleRegistration(txn, vin, newOwner);
           });
           log.info("Successfully transferred vehicle ownership!");
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonReader;
   import com.amazon.ion.IonStruct;
   import com.amazon.ion.IonValue;
   import com.amazon.ion.system.IonReaderBuilder;
   
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.LinkedHashMap;
   import java.util.List;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.Owner;
   import software.amazon.qldb.tutorial.model.Person;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Find primary owner for a particular vehicle's VIN.
    * Transfer to another primary owner for a particular vehicle's VIN.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class TransferVehicleOwnership {
       public static final Logger log = LoggerFactory.getLogger(TransferVehicleOwnership.class);
   
       private TransferVehicleOwnership() { }
   
       /**
        * Query a driver's information using the given ID.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param documentId
        *              The unique ID of a document in the Person table.
        * @return a {@link Person} object.
        * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
        */
       public static Person findPersonFromDocumentId(final TransactionExecutor txn, final String documentId) {
           try {
               log.info("Finding person for documentId: {}...", documentId);
               final String query = "SELECT p.* FROM Person AS p BY pid WHERE pid = ?";
   
               Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(documentId));
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to find person with ID: " + documentId);
               }
   
               return Constants.MAPPER.readValue(result.iterator().next(), Person.class);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Find the primary owner for the given VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @return a {@link Person} object.
        * @throws IllegalStateException if failed to convert parameter into {@link IonValue}.
        */
       public static Person findPrimaryOwnerForVehicle(final TransactionExecutor txn, final String vin) {
           try {
               log.info("Finding primary owner for vehicle with Vin: {}...", vin);
               final String query = "SELECT Owners.PrimaryOwner.PersonId FROM VehicleRegistration AS v WHERE v.VIN = ?";
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
               Result result = txn.execute(query, parameters);
               final List<IonStruct> documents = ScanTable.toIonStructs(result);
               ScanTable.printDocuments(documents);
               if (documents.isEmpty()) {
                   throw new IllegalStateException("Unable to find registrations with VIN: " + vin);
               }
   
               final IonReader reader = IonReaderBuilder.standard().build(documents.get(0));
               final String personId = Constants.MAPPER.readValue(reader, LinkedHashMap.class).get("PersonId").toString();
               return findPersonFromDocumentId(txn, personId);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Update the primary owner for a vehicle registration with the given documentId.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @param documentId
        *              New PersonId for the primary owner.
        * @throws IllegalStateException if no vehicle registration was found using the given document ID and VIN, or if failed
        * to convert parameters into {@link IonValue}.
        */
       public static void updateVehicleRegistration(final TransactionExecutor txn, final String vin, final String documentId) {
           try {
               log.info("Updating primary owner for vehicle with Vin: {}...", vin);
               final String query = "UPDATE VehicleRegistration AS v SET v.Owners.PrimaryOwner = ? WHERE v.VIN = ?";
   
               final List<IonValue> parameters = new ArrayList<>();
               parameters.add(Constants.MAPPER.writeValueAsIonValue(new Owner(documentId)));
               parameters.add(Constants.MAPPER.writeValueAsIonValue(vin));
   
               Result result = txn.execute(query, parameters);
               ScanTable.printDocuments(result);
               if (result.isEmpty()) {
                   throw new IllegalStateException("Unable to transfer vehicle, could not find registration.");
               } else {
                   log.info("Successfully transferred vehicle with VIN '{}' to new owner.", vin);
               }
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       public static void main(final String... args) {
           final String vin = SampleData.VEHICLES.get(0).getVin();
           final String primaryOwnerGovId = SampleData.PEOPLE.get(0).getGovId();
           final String newPrimaryOwnerGovId = SampleData.PEOPLE.get(1).getGovId();
   
           ConnectToLedger.getDriver().execute(txn -> {
               final Person primaryOwner = findPrimaryOwnerForVehicle(txn, vin);
               if (!primaryOwner.getGovId().equals(primaryOwnerGovId)) {
                   // Verify the primary owner.
                   throw new IllegalStateException("Incorrect primary owner identified for vehicle, unable to transfer.");
               }
   
               final String newOwner = Person.getDocumentIdByGovId(txn, newPrimaryOwnerGovId);
               updateVehicleRegistration(txn, vin, newOwner);
           }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
           log.info("Successfully transferred vehicle ownership!");
       }
   }
   ```

------

1. Kompilieren Sie das folgende Programm (`AddSecondaryOwner.java`) und führen Sie es aus, um dem Fahrzeug mit VIN `KM8SRDHF6EU074761` in Ihrem Ledger einen sekundären Eigentümer hinzuzufügen.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import java.io.IOException;
   import java.util.Collections;
   import java.util.Iterator;
   import java.util.List;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import com.amazon.ion.IonValue;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.Owner;
   import software.amazon.qldb.tutorial.model.Owners;
   import software.amazon.qldb.tutorial.model.Person;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Finds and adds secondary owners for a vehicle.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class AddSecondaryOwner {
       public static final Logger log = LoggerFactory.getLogger(AddSecondaryOwner.class);
   
       private AddSecondaryOwner() { }
   
       /**
        * Check whether a secondary owner has already been registered for the given VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @param secondaryOwnerId
        *              The secondary owner to add.
        * @return {@code true} if the given secondary owner has already been registered, {@code false} otherwise.
        * @throws IllegalStateException if failed to convert VIN to an {@link IonValue}.
        */
       public static boolean isSecondaryOwnerForVehicle(final TransactionExecutor txn, final String vin,
                                                        final String secondaryOwnerId) {
           try {
               log.info("Finding secondary owners for vehicle with VIN: {}...", vin);
               final String query = "SELECT Owners.SecondaryOwners FROM VehicleRegistration AS v WHERE v.VIN = ?";
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
               final Result result = txn.execute(query, parameters);
               final Iterator<IonValue> itr = result.iterator();
               if (!itr.hasNext()) {
                   return false;
               }
   
               final Owners owners = Constants.MAPPER.readValue(itr.next(), Owners.class);
               if (null != owners.getSecondaryOwners()) {
                   for (Owner owner : owners.getSecondaryOwners()) {
                       if (secondaryOwnerId.equalsIgnoreCase(owner.getPersonId())) {
                           return true;
                       }
                   }
               }
   
               return false;
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Adds a secondary owner for the specified VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @param secondaryOwner
        *              The secondary owner to add.
        * @throws IllegalStateException if failed to convert parameter into an {@link IonValue}.
        */
       public static void addSecondaryOwnerForVin(final TransactionExecutor txn, final String vin,
                                                  final String secondaryOwner) {
           try {
               log.info("Inserting secondary owner for vehicle with VIN: {}...", vin);
               final String query = String.format("FROM VehicleRegistration AS v WHERE v.VIN = ?" +
                       "INSERT INTO v.Owners.SecondaryOwners VALUE ?");
               final IonValue newOwner = Constants.MAPPER.writeValueAsIonValue(new Owner(secondaryOwner));
               final IonValue vinAsIonValue = Constants.MAPPER.writeValueAsIonValue(vin);
               Result result = txn.execute(query, vinAsIonValue, newOwner);
               log.info("VehicleRegistration Document IDs which had secondary owners added: ");
               ScanTable.printDocuments(result);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       public static void main(final String... args) {
           final String vin = SampleData.VEHICLES.get(1).getVin();
           final String govId = SampleData.PEOPLE.get(0).getGovId();
   
           ConnectToLedger.getDriver().execute(txn -> {
               final String documentId = Person.getDocumentIdByGovId(txn, govId);
               if (isSecondaryOwnerForVehicle(txn, vin, documentId)) {
                   log.info("Person with ID {} has already been added as a secondary owner of this vehicle.", govId);
               } else {
                   addSecondaryOwnerForVin(txn, vin, documentId);
               }
           });
           log.info("Secondary owners successfully updated.");
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import java.io.IOException;
   import java.util.Collections;
   import java.util.Iterator;
   import java.util.List;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import com.amazon.ion.IonValue;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.Owner;
   import software.amazon.qldb.tutorial.model.Owners;
   import software.amazon.qldb.tutorial.model.Person;
   import software.amazon.qldb.tutorial.model.SampleData;
   
   /**
    * Finds and adds secondary owners for a vehicle.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class AddSecondaryOwner {
       public static final Logger log = LoggerFactory.getLogger(AddSecondaryOwner.class);
   
       private AddSecondaryOwner() { }
   
       /**
        * Check whether a secondary owner has already been registered for the given VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @param secondaryOwnerId
        *              The secondary owner to add.
        * @return {@code true} if the given secondary owner has already been registered, {@code false} otherwise.
        * @throws IllegalStateException if failed to convert VIN to an {@link IonValue}.
        */
       public static boolean isSecondaryOwnerForVehicle(final TransactionExecutor txn, final String vin,
                                                        final String secondaryOwnerId) {
           try {
               log.info("Finding secondary owners for vehicle with VIN: {}...", vin);
               final String query = "SELECT Owners.SecondaryOwners FROM VehicleRegistration AS v WHERE v.VIN = ?";
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
               final Result result = txn.execute(query, parameters);
               final Iterator<IonValue> itr = result.iterator();
               if (!itr.hasNext()) {
                   return false;
               }
   
               final Owners owners = Constants.MAPPER.readValue(itr.next(), Owners.class);
               if (null != owners.getSecondaryOwners()) {
                   for (Owner owner : owners.getSecondaryOwners()) {
                       if (secondaryOwnerId.equalsIgnoreCase(owner.getPersonId())) {
                           return true;
                       }
                   }
               }
   
               return false;
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Adds a secondary owner for the specified VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              Unique VIN for a vehicle.
        * @param secondaryOwner
        *              The secondary owner to add.
        * @throws IllegalStateException if failed to convert parameter into an {@link IonValue}.
        */
       public static void addSecondaryOwnerForVin(final TransactionExecutor txn, final String vin,
                                                  final String secondaryOwner) {
           try {
               log.info("Inserting secondary owner for vehicle with VIN: {}...", vin);
               final String query = String.format("FROM VehicleRegistration AS v WHERE v.VIN = '%s' " +
                       "INSERT INTO v.Owners.SecondaryOwners VALUE ?", vin);
               final IonValue newOwner = Constants.MAPPER.writeValueAsIonValue(new Owner(secondaryOwner));
               Result result = txn.execute(query, newOwner);
               log.info("VehicleRegistration Document IDs which had secondary owners added: ");
               ScanTable.printDocuments(result);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       public static void main(final String... args) {
           final String vin = SampleData.VEHICLES.get(1).getVin();
           final String govId = SampleData.PEOPLE.get(0).getGovId();
   
           ConnectToLedger.getDriver().execute(txn -> {
               final String documentId = Person.getDocumentIdByGovId(txn, govId);
               if (isSecondaryOwnerForVehicle(txn, vin, documentId)) {
                   log.info("Person with ID {} has already been added as a secondary owner of this vehicle.", govId);
               } else {
                   addSecondaryOwnerForVin(txn, vin, documentId);
               }
           }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
           log.info("Secondary owners successfully updated.");
       }
   }
   ```

------

Informationen zum Überprüfen dieser Änderungen im `vehicle-registration`-Ledger finden Sie unter [Schritt 6: Den Revisionsverlauf für ein Dokument anzeigen](getting-started.java.step-6.md).

# Schritt 6: Den Revisionsverlauf für ein Dokument anzeigen
<a name="getting-started.java.step-6"></a>

**Wichtig**  
Hinweis zum Ende des Supports: Bestandskunden können Amazon QLDB bis zum Ende des Supports am 31.07.2025 nutzen. Weitere Informationen finden Sie unter [Migrieren eines Amazon QLDB-Ledgers zu Amazon](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/) Aurora PostgreSQL.

Nach dem Bearbeiten der Zulassungsdaten für ein Fahrzeug im vorherigen Schritt können Sie den Verlauf aller registrierten Eigentümer und alle anderen aktualisierten Felder abfragen. In diesem Schritt führen Sie eine Abfrage des Revisionsverlaufs eines Dokuments in der `VehicleRegistration`-Tabelle in Ihrem `vehicle-registration`-Ledger durch.

**So zeigen Sie den Revisionsverlauf an**

1. Überprüfen Sie das folgende Programm (`QueryHistory.java`).

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import java.io.IOException;
   import java.time.Instant;
   import java.time.temporal.ChronoUnit;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import com.amazon.ion.IonValue;
   
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   import software.amazon.qldb.tutorial.model.VehicleRegistration;
   
   /**
    * Query a table's history for a particular set of documents.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class QueryHistory {
       public static final Logger log = LoggerFactory.getLogger(QueryHistory.class);
       private static final int THREE_MONTHS = 90;
   
       private QueryHistory() { }
   
       /**
        * In this example, query the 'VehicleRegistration' history table to find all previous primary owners for a VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              VIN to find previous primary owners for.
        * @param query
        *              The query to find previous primary owners.
        * @throws IllegalStateException if failed to convert document ID to an {@link IonValue}.
        */
       public static void previousPrimaryOwners(final TransactionExecutor txn, final String vin, final String query) {
           try {
               final String docId = VehicleRegistration.getDocumentIdByVin(txn, vin);
   
               log.info("Querying the 'VehicleRegistration' table's history using VIN: {}...", vin);
               final Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(docId));
               ScanTable.printDocuments(result);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       public static void main(final String... args) {
           final String threeMonthsAgo = Instant.now().minus(THREE_MONTHS, ChronoUnit.DAYS).toString();
           final String query = String.format("SELECT data.Owners.PrimaryOwner, metadata.version "
                                              + "FROM history(VehicleRegistration, `%s`) "
                                              + "AS h WHERE h.metadata.id = ?", threeMonthsAgo);
           ConnectToLedger.getDriver().execute(txn -> {
               final String vin = SampleData.VEHICLES.get(0).getVin();
               previousPrimaryOwners(txn, vin, query);
           });
           log.info("Successfully queried history.");
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonValue;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.QldbSession;
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   import software.amazon.qldb.tutorial.model.VehicleRegistration;
   
   import java.io.IOException;
   import java.time.Instant;
   import java.time.temporal.ChronoUnit;
   import java.util.Collections;
   import java.util.List;
   
   /**
    * Query a table's history for a particular set of documents.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class QueryHistory {
       public static final Logger log = LoggerFactory.getLogger(QueryHistory.class);
       private static final int THREE_MONTHS = 90;
   
       private QueryHistory() { }
   
       /**
        * In this example, query the 'VehicleRegistration' history table to find all previous primary owners for a VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              VIN to find previous primary owners for.
        * @param query
        *              The query to find previous primary owners.
        * @throws IllegalStateException if failed to convert document ID to an {@link IonValue}.
        */
       public static void previousPrimaryOwners(final TransactionExecutor txn, final String vin, final String query) {
           try {
               final String docId = VehicleRegistration.getDocumentIdByVin(txn, vin);
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(docId));
               log.info("Querying the 'VehicleRegistration' table's history using VIN: {}...", vin);
               final Result result = txn.execute(query, parameters);
               ScanTable.printDocuments(result);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       public static void main(final String... args) {
           final String threeMonthsAgo = Instant.now().minus(THREE_MONTHS, ChronoUnit.DAYS).toString();
           final String query = String.format("SELECT data.Owners.PrimaryOwner, metadata.version "
                                              + "FROM history(VehicleRegistration, `%s`) "
                                              + "AS h WHERE h.metadata.id = ?", threeMonthsAgo);
           ConnectToLedger.getDriver().execute(txn -> {
               final String vin = SampleData.VEHICLES.get(0).getVin();
               previousPrimaryOwners(txn, vin, query);
           }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
           log.info("Successfully queried history.");
       }
   }
   ```

------
**Anmerkung**  
Sie können den Revisionsverlauf eines Dokuments anzeigen, indem Sie die integrierte [Funktion „Verlauf“](working.history.md#working.history.function) in der folgenden Syntax abfragen.  

     ```
     SELECT * FROM history( table_name [, `start-time` [, `end-time` ] ] ) AS h
     [ WHERE h.metadata.id = 'id' ]
     ```
*Die *Startzeit und die Endzeit sind beide optional*.* Es handelt sich um Amazon Ion-Literalwerte, die mit Backticks () bezeichnet werden können. ``...`` Weitere Informationen hierzu finden Sie unter [Abfragen von Ion mit PartiQL in Amazon QLDB](ql-reference.query.md).
Es hat sich bewährt, eine Verlaufsabfrage sowohl mit einem Datumsbereich (*Start- und *Endzeit*) als auch mit einer Dokument-ID* () zu qualifizieren. `metadata.id` QLDB verarbeitet `SELECT` Abfragen in Transaktionen, die einem [Transaktions-Timeout-Limit](limits.md#limits.fixed) unterliegen.  
Der QLDB-Verlauf wird nach Dokument-ID indexiert, und Sie können derzeit keine zusätzlichen Verlaufsindizes erstellen. Bei Verlaufsabfragen, die eine Start- und Endzeit enthalten, wird der Vorteil einer Qualifizierung nach einem bestimmten Zeitraum genutzt.

1. Kompilieren Sie das `QueryHistory.java` Programm und führen Sie es aus, um den Revisionsverlauf des `VehicleRegistration` Dokuments mit VIN abzufragen`1N4AL11D75C109151`.

Fahren Sie zum kryptografischen Überprüfen einer Dokumentrevision im `vehicle-registration`-Ledger mit [Schritt 7: Überprüfen Sie ein Dokument in einem Hauptbuch](getting-started.java.step-7.md) fort.

# Schritt 7: Überprüfen Sie ein Dokument in einem Hauptbuch
<a name="getting-started.java.step-7"></a>

**Wichtig**  
Hinweis zum Ende des Supports: Bestandskunden können Amazon QLDB bis zum Ende des Supports am 31.07.2025 nutzen. Weitere Informationen finden Sie unter [Migrieren eines Amazon QLDB-Ledgers zu Amazon](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/) Aurora PostgreSQL.

Mit Amazon QLDB können Sie die Integrität eines Dokuments im Journal Ihres Hauptbuchs effizient überprüfen, indem Sie kryptografisches Hashing mit SHA-256 verwenden. Weitere Informationen darüber, wie Verifizierung und kryptografisches Hashing in QLDB funktionieren, finden Sie unter. [Datenüberprüfung in Amazon QLDB](verification.md)

In diesem Schritt überprüfen Sie eine Dokumentrevision in der Tabelle `VehicleRegistration` in Ihrem `vehicle-registration`-Ledger. Zuerst fordern Sie einen Digest an, der als Ausgabedatei zurückgegeben wird und als Signatur des gesamten Änderungsverlaufs Ihres Ledgers fungiert. Anschließend fordern Sie einen Nachweis für die Revision in Bezug auf diesen Digest an. Mit diesem Nachweis wird die Integrität Ihrer Revision verifiziert, wenn alle Validierungsprüfungen bestanden werden.

**So überprüfen Sie eine Dokumentrevision**

1. Sehen Sie sich die folgenden `.java` Dateien an, die QLDB-Objekte darstellen, die für die Überprüfung erforderlich sind, und Hilfsklassen mit Hilfsmethoden für Ion- und Zeichenkettenwerte.

   1. `BlockAddress.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import java.util.Objects;
      
      import org.slf4j.Logger;
      import org.slf4j.LoggerFactory;
      
      import com.fasterxml.jackson.annotation.JsonCreator;
      import com.fasterxml.jackson.annotation.JsonProperty;
      
      /**
       * Represents the BlockAddress field of a QLDB document.
       */
      public final class BlockAddress {
      
          private static final Logger log = LoggerFactory.getLogger(BlockAddress.class);
      
          private final String strandId;
          private final long sequenceNo;
      
          @JsonCreator
          public BlockAddress(@JsonProperty("strandId") final String strandId,
                              @JsonProperty("sequenceNo") final long sequenceNo) {
              this.strandId = strandId;
              this.sequenceNo = sequenceNo;
          }
      
          public long getSequenceNo() {
              return sequenceNo;
          }
      
          public String getStrandId() {
              return strandId;
          }
      
          @Override
          public String toString() {
              return "BlockAddress{"
                      + "strandId='" + strandId + '\''
                      + ", sequenceNo=" + sequenceNo
                      + '}';
          }
      
          @Override
          public boolean equals(final Object o) {
              if (this == o) {
                  return true;
              }
              if (o == null || getClass() != o.getClass()) {
                  return false;
              }
              BlockAddress that = (BlockAddress) o;
              return sequenceNo == that.sequenceNo
                      && strandId.equals(that.strandId);
          }
      
          @Override
          public int hashCode() {
              // CHECKSTYLE:OFF - Disabling as we are generating a hashCode of multiple properties.
              return Objects.hash(strandId, sequenceNo);
              // CHECKSTYLE:ON
          }
      }
      ```

   1. `Proof.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import com.amazon.ion.IonReader;
      import com.amazon.ion.IonSystem;
      import com.amazon.ion.system.IonSystemBuilder;
      import com.amazonaws.services.qldb.model.GetRevisionRequest;
      import com.amazonaws.services.qldb.model.GetRevisionResult;
      
      import java.util.ArrayList;
      import java.util.List;
      
      /**
       * A Java representation of the {@link Proof} object.
       * Returned from the {@link com.amazonaws.services.qldb.AmazonQLDB#getRevision(GetRevisionRequest)} api.
       */
      public final class Proof {
          private static final IonSystem SYSTEM = IonSystemBuilder.standard().build();
      
          private List<byte[]> internalHashes;
      
          public Proof(final List<byte[]> internalHashes) {
              this.internalHashes = internalHashes;
          }
      
          public List<byte[]> getInternalHashes() {
              return internalHashes;
          }
      
          /**
           * Decodes a {@link Proof} from an ion text String. This ion text is returned in
           * a {@link GetRevisionResult#getProof()}
           *
           * @param ionText
           *              The ion text representing a {@link Proof} object.
           * @return {@link JournalBlock} parsed from the ion text.
           * @throws IllegalStateException if failed to parse the {@link Proof} object from the given ion text.
           */
          public static Proof fromBlob(final String ionText) {
              try {
                  IonReader reader = SYSTEM.newReader(ionText);
                  List<byte[]> list = new ArrayList<>();
                  reader.next();
                  reader.stepIn();
                  while (reader.next() != null) {
                      list.add(reader.newBytes());
                  }
                  return new Proof(list);
              } catch (Exception e) {
                  throw new IllegalStateException("Failed to parse a Proof from byte array");
              }
          }
      }
      ```

   1. `QldbIonUtils.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import com.amazon.ion.IonReader;
      import com.amazon.ion.IonValue;
      import com.amazon.ionhash.IonHashReader;
      import com.amazon.ionhash.IonHashReaderBuilder;
      import com.amazon.ionhash.MessageDigestIonHasherProvider;
      import software.amazon.qldb.tutorial.Constants;
      
      public class QldbIonUtils {
      
          private static MessageDigestIonHasherProvider ionHasherProvider = new MessageDigestIonHasherProvider("SHA-256");
      
          private QldbIonUtils() {}
      
          /**
           * Builds a hash value from the given {@link IonValue}.
           *
           * @param ionValue
           *              The {@link IonValue} to hash.
           * @return a byte array representing the hash value.
           */
          public static byte[] hashIonValue(final IonValue ionValue) {
              IonReader reader = Constants.SYSTEM.newReader(ionValue);
              IonHashReader hashReader = IonHashReaderBuilder.standard()
                      .withHasherProvider(ionHasherProvider)
                      .withReader(reader)
                      .build();
              while (hashReader.next() != null) {  }
              return hashReader.digest();
          }
      
      }
      ```

   1. `QldbStringUtils.java`

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial.qldb;
      
      import com.amazon.ion.IonWriter;
      import com.amazon.ion.system.IonReaderBuilder;
      import com.amazon.ion.system.IonTextWriterBuilder;
      import com.amazonaws.services.qldb.model.GetBlockResult;
      import com.amazonaws.services.qldb.model.GetDigestResult;
      import com.amazonaws.services.qldb.model.ValueHolder;
      
      import java.io.IOException;
      
      /**
       * Helper methods to pretty-print certain QLDB response types.
       */
      public class QldbStringUtils {
      
          private QldbStringUtils() {}
      
          /**
           * Returns the string representation of a given {@link ValueHolder}.
           * Adapted from the AWS SDK autogenerated {@code toString()} method, with sensitive values un-redacted.
           * Additionally, this method pretty-prints any IonText included in the {@link ValueHolder}.
           *
           * @param valueHolder the {@link ValueHolder} to convert to a String.
           * @return the String representation of the supplied {@link ValueHolder}.
           */
          public static String toUnredactedString(ValueHolder valueHolder) {
              StringBuilder sb = new StringBuilder();
              sb.append("{");
              if (valueHolder.getIonText() != null) {
      
                  sb.append("IonText: ");
                  IonWriter prettyWriter = IonTextWriterBuilder.pretty().build(sb);
                  try {
                      prettyWriter.writeValues(IonReaderBuilder.standard().build(valueHolder.getIonText()));
                  } catch (IOException ioe) {
                      sb.append("**Exception while printing this IonText**");
                  }
              }
      
              sb.append("}");
              return sb.toString();
          }
      
          /**
           * Returns the string representation of a given {@link GetBlockResult}.
           * Adapted from the AWS SDK autogenerated {@code toString()} method, with sensitive values un-redacted.
           *
           * @param getBlockResult the {@link GetBlockResult} to convert to a String.
           * @return the String representation of the supplied {@link GetBlockResult}.
           */
          public static String toUnredactedString(GetBlockResult getBlockResult) {
              StringBuilder sb = new StringBuilder();
              sb.append("{");
              if (getBlockResult.getBlock() != null) {
                  sb.append("Block: ").append(toUnredactedString(getBlockResult.getBlock())).append(",");
              }
      
              if (getBlockResult.getProof() != null) {
                  sb.append("Proof: ").append(toUnredactedString(getBlockResult.getProof()));
              }
      
              sb.append("}");
              return sb.toString();
          }
      
          /**
           * Returns the string representation of a given {@link GetDigestResult}.
           * Adapted from the AWS SDK autogenerated {@code toString()} method, with sensitive values un-redacted.
           *
           * @param getDigestResult the {@link GetDigestResult} to convert to a String.
           * @return the String representation of the supplied {@link GetDigestResult}.
           */
          public static String toUnredactedString(GetDigestResult getDigestResult) {
              StringBuilder sb = new StringBuilder();
              sb.append("{");
              if (getDigestResult.getDigest() != null) {
                  sb.append("Digest: ").append(getDigestResult.getDigest()).append(",");
              }
      
              if (getDigestResult.getDigestTipAddress() != null) {
                  sb.append("DigestTipAddress: ").append(toUnredactedString(getDigestResult.getDigestTipAddress()));
              }
      
              sb.append("}");
              return sb.toString();
          }
      }
      ```

   1. `Verifier.java`

------
#### [ 2.x ]

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial;
      
      import java.nio.ByteBuffer;
      import java.nio.charset.StandardCharsets;
      import java.security.MessageDigest;
      import java.security.NoSuchAlgorithmException;
      import java.util.ArrayList;
      import java.util.Arrays;
      import java.util.Comparator;
      import java.util.Iterator;
      import java.util.List;
      import java.util.concurrent.ThreadLocalRandom;
      
      import org.slf4j.Logger;
      import org.slf4j.LoggerFactory;
      
      import com.amazonaws.util.Base64;
      
      import software.amazon.qldb.tutorial.qldb.Proof;
      
      /**
       * Encapsulates the logic to verify the integrity of revisions or blocks in a QLDB ledger.
       *
       * The main entry point is {@link #verify(byte[], byte[], String)}.
       *
       * This code expects that you have AWS credentials setup per:
       * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
       */
      public final class Verifier {
          public static final Logger log = LoggerFactory.getLogger(Verifier.class);
          private static final int HASH_LENGTH = 32;
          private static final int UPPER_BOUND = 8;
      
          /**
           * Compares two hashes by their <em>signed</em> byte values in little-endian order.
           */
          private static Comparator<byte[]> hashComparator = (h1, h2) -> {
              if (h1.length != HASH_LENGTH || h2.length != HASH_LENGTH) {
                  throw new IllegalArgumentException("Invalid hash.");
              }
              for (int i = h1.length - 1; i >= 0; i--) {
                  int byteEqual = Byte.compare(h1[i], h2[i]);
                  if (byteEqual != 0) {
                      return byteEqual;
                  }
              }
      
              return 0;
          };
      
          private Verifier() { }
      
          /**
           * Verify the integrity of a document with respect to a QLDB ledger digest.
           *
           * The verification algorithm includes the following steps:
           *
           * 1. {@link #buildCandidateDigest(Proof, byte[])} build the candidate digest from the internal hashes
           * in the {@link Proof}.
           * 2. Check that the {@code candidateLedgerDigest} is equal to the {@code ledgerDigest}.
           *
           * @param documentHash
           *              The hash of the document to be verified.
           * @param digest
           *              The QLDB ledger digest. This digest should have been retrieved using
           *              {@link com.amazonaws.services.qldb.AmazonQLDB#getDigest}
           * @param proofBlob
           *              The ion encoded bytes representing the {@link Proof} associated with the supplied
           *              {@code digestTipAddress} and {@code address} retrieved using
           *              {@link com.amazonaws.services.qldb.AmazonQLDB#getRevision}.
           * @return {@code true} if the record is verified or {@code false} if it is not verified.
           */
          public static boolean verify(
                  final byte[] documentHash,
                  final byte[] digest,
                  final String proofBlob
          ) {
              Proof proof = Proof.fromBlob(proofBlob);
      
              byte[] candidateDigest = buildCandidateDigest(proof, documentHash);
      
              return Arrays.equals(digest, candidateDigest);
          }
      
          /**
           * Build the candidate digest representing the entire ledger from the internal hashes of the {@link Proof}.
           *
           * @param proof
           *              A Java representation of {@link Proof}
           *              returned from {@link com.amazonaws.services.qldb.AmazonQLDB#getRevision}.
           * @param leafHash
           *              Leaf hash to build the candidate digest with.
           * @return a byte array of the candidate digest.
           */
          private static byte[] buildCandidateDigest(final Proof proof, final byte[] leafHash) {
              return calculateRootHashFromInternalHashes(proof.getInternalHashes(), leafHash);
          }
      
          /**
           * Get a new instance of {@link MessageDigest} using the SHA-256 algorithm.
           *
           * @return an instance of {@link MessageDigest}.
           * @throws IllegalStateException if the algorithm is not available on the current JVM.
           */
          static MessageDigest newMessageDigest() {
              try {
                  return MessageDigest.getInstance("SHA-256");
              } catch (NoSuchAlgorithmException e) {
                  log.error("Failed to create SHA-256 MessageDigest", e);
                  throw new IllegalStateException("SHA-256 message digest is unavailable", e);
              }
          }
      
          /**
           * Takes two hashes, sorts them, concatenates them, and then returns the
           * hash of the concatenated array.
           *
           * @param h1
           *              Byte array containing one of the hashes to compare.
           * @param h2
           *              Byte array containing one of the hashes to compare.
           * @return the concatenated array of hashes.
           */
          public static byte[] dot(final byte[] h1, final byte[] h2) {
              if (h1.length == 0) {
                  return h2;
              }
              if (h2.length == 0) {
                  return h1;
              }
              byte[] concatenated = new byte[h1.length + h2.length];
              if (hashComparator.compare(h1, h2) < 0) {
                  System.arraycopy(h1, 0, concatenated, 0, h1.length);
                  System.arraycopy(h2, 0, concatenated, h1.length, h2.length);
              } else {
                  System.arraycopy(h2, 0, concatenated, 0, h2.length);
                  System.arraycopy(h1, 0, concatenated, h2.length, h1.length);
              }
              MessageDigest messageDigest = newMessageDigest();
              messageDigest.update(concatenated);
      
              return messageDigest.digest();
          }
      
          /**
           * Starting with the provided {@code leafHash} combined with the provided {@code internalHashes}
           * pairwise until only the root hash remains.
           *
           * @param internalHashes
           *              Internal hashes of Merkle tree.
           * @param leafHash
           *              Leaf hashes of Merkle tree.
           * @return the root hash.
           */
          private static byte[] calculateRootHashFromInternalHashes(final List<byte[]> internalHashes, final byte[] leafHash) {
              return internalHashes.stream().reduce(leafHash, Verifier::dot);
          }
      
          /**
           * Flip a single random bit in the given byte array. This method is used to demonstrate
           * QLDB's verification features.
           *
           * @param original
           *              The original byte array.
           * @return the altered byte array with a single random bit changed.
           */
          public static byte[] flipRandomBit(final byte[] original) {
              if (original.length == 0) {
                  throw new IllegalArgumentException("Array cannot be empty!");
              }
              int alteredPosition = ThreadLocalRandom.current().nextInt(original.length);
              int b = ThreadLocalRandom.current().nextInt(UPPER_BOUND);
              byte[] altered = new byte[original.length];
              System.arraycopy(original, 0, altered, 0, original.length);
              altered[alteredPosition] = (byte) (altered[alteredPosition] ^ (1 << b));
              return altered;
          }
      
          public static String toBase64(byte[] arr) {
              return new String(Base64.encode(arr), StandardCharsets.UTF_8);
          }
      
          /**
           * Convert a {@link ByteBuffer} into byte array.
           *
           * @param buffer
           *              The {@link ByteBuffer} to convert.
           * @return the converted byte array.
           */
          public static byte[] convertByteBufferToByteArray(final ByteBuffer buffer) {
              byte[] arr = new byte[buffer.remaining()];
              buffer.get(arr);
              return arr;
          }
      
          /**
           * Calculates the root hash from a list of hashes that represent the base of a Merkle tree.
           *
           * @param hashes
           *              The list of byte arrays representing hashes making up base of a Merkle tree.
           * @return a byte array that is the root hash of the given list of hashes.
           */
          public static byte[] calculateMerkleTreeRootHash(List<byte[]> hashes) {
              if (hashes.isEmpty()) {
                  return new byte[0];
              }
      
              List<byte[]> remaining = combineLeafHashes(hashes);
              while (remaining.size() > 1) {
                  remaining = combineLeafHashes(remaining);
              }
              return remaining.get(0);
          }
      
          private static List<byte[]> combineLeafHashes(List<byte[]> hashes) {
              List<byte[]> combinedHashes = new ArrayList<>();
              Iterator<byte[]> it = hashes.stream().iterator();
      
              while (it.hasNext()) {
                  byte[] left = it.next();
                  if (it.hasNext()) {
                      byte[] right = it.next();
                      byte[] combined = dot(left, right);
                      combinedHashes.add(combined);
                  } else {
                      combinedHashes.add(left);
                  }
              }
      
              return combinedHashes;
          }
      }
      ```

------
#### [ 1.x ]

      ```
      /*
       * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
       * SPDX-License-Identifier: MIT-0
       *
       * Permission is hereby granted, free of charge, to any person obtaining a copy of this
       * software and associated documentation files (the "Software"), to deal in the Software
       * without restriction, including without limitation the rights to use, copy, modify,
       * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
       * permit persons to whom the Software is furnished to do so.
       *
       * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
       * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
       * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
       * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
       * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
       * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
       */
      
      package software.amazon.qldb.tutorial;
      
      import com.amazonaws.util.Base64;
      import org.slf4j.Logger;
      import org.slf4j.LoggerFactory;
      import software.amazon.qldb.tutorial.qldb.Proof;
      
      import java.nio.ByteBuffer;
      import java.nio.charset.StandardCharsets;
      import java.security.MessageDigest;
      import java.security.NoSuchAlgorithmException;
      import java.util.*;
      import java.util.concurrent.ThreadLocalRandom;
      
      /**
       * Encapsulates the logic to verify the integrity of revisions or blocks in a QLDB ledger.
       *
       * The main entry point is {@link #verify(byte[], byte[], String)}.
       *
       * This code expects that you have AWS credentials setup per:
       * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
       */
      public final class Verifier {
          public static final Logger log = LoggerFactory.getLogger(Verifier.class);
          private static final int HASH_LENGTH = 32;
          private static final int UPPER_BOUND = 8;
      
          /**
           * Compares two hashes by their <em>signed</em> byte values in little-endian order.
           */
          private static Comparator<byte[]> hashComparator = (h1, h2) -> {
              if (h1.length != HASH_LENGTH || h2.length != HASH_LENGTH) {
                  throw new IllegalArgumentException("Invalid hash.");
              }
              for (int i = h1.length - 1; i >= 0; i--) {
                  int byteEqual = Byte.compare(h1[i], h2[i]);
                  if (byteEqual != 0) {
                      return byteEqual;
                  }
              }
      
              return 0;
          };
      
          private Verifier() { }
      
          /**
           * Verify the integrity of a document with respect to a QLDB ledger digest.
           *
           * The verification algorithm includes the following steps:
           *
           * 1. {@link #buildCandidateDigest(Proof, byte[])} build the candidate digest from the internal hashes
           * in the {@link Proof}.
           * 2. Check that the {@code candidateLedgerDigest} is equal to the {@code ledgerDigest}.
           *
           * @param documentHash
           *              The hash of the document to be verified.
           * @param digest
           *              The QLDB ledger digest. This digest should have been retrieved using
           *              {@link com.amazonaws.services.qldb.AmazonQLDB#getDigest}
           * @param proofBlob
           *              The ion encoded bytes representing the {@link Proof} associated with the supplied
           *              {@code digestTipAddress} and {@code address} retrieved using
           *              {@link com.amazonaws.services.qldb.AmazonQLDB#getRevision}.
           * @return {@code true} if the record is verified or {@code false} if it is not verified.
           */
          public static boolean verify(
                  final byte[] documentHash,
                  final byte[] digest,
                  final String proofBlob
          ) {
              Proof proof = Proof.fromBlob(proofBlob);
      
              byte[] candidateDigest = buildCandidateDigest(proof, documentHash);
      
              return Arrays.equals(digest, candidateDigest);
          }
      
          /**
           * Build the candidate digest representing the entire ledger from the internal hashes of the {@link Proof}.
           *
           * @param proof
           *              A Java representation of {@link Proof}
           *              returned from {@link com.amazonaws.services.qldb.AmazonQLDB#getRevision}.
           * @param leafHash
           *              Leaf hash to build the candidate digest with.
           * @return a byte array of the candidate digest.
           */
          private static byte[] buildCandidateDigest(final Proof proof, final byte[] leafHash) {
              return calculateRootHashFromInternalHashes(proof.getInternalHashes(), leafHash);
          }
      
          /**
           * Get a new instance of {@link MessageDigest} using the SHA-256 algorithm.
           *
           * @return an instance of {@link MessageDigest}.
           * @throws IllegalStateException if the algorithm is not available on the current JVM.
           */
          static MessageDigest newMessageDigest() {
              try {
                  return MessageDigest.getInstance("SHA-256");
              } catch (NoSuchAlgorithmException e) {
                  log.error("Failed to create SHA-256 MessageDigest", e);
                  throw new IllegalStateException("SHA-256 message digest is unavailable", e);
              }
          }
      
          /**
           * Takes two hashes, sorts them, concatenates them, and then returns the
           * hash of the concatenated array.
           *
           * @param h1
           *              Byte array containing one of the hashes to compare.
           * @param h2
           *              Byte array containing one of the hashes to compare.
           * @return the concatenated array of hashes.
           */
          public static byte[] dot(final byte[] h1, final byte[] h2) {
              if (h1.length == 0) {
                  return h2;
              }
              if (h2.length == 0) {
                  return h1;
              }
              byte[] concatenated = new byte[h1.length + h2.length];
              if (hashComparator.compare(h1, h2) < 0) {
                  System.arraycopy(h1, 0, concatenated, 0, h1.length);
                  System.arraycopy(h2, 0, concatenated, h1.length, h2.length);
              } else {
                  System.arraycopy(h2, 0, concatenated, 0, h2.length);
                  System.arraycopy(h1, 0, concatenated, h2.length, h1.length);
              }
              MessageDigest messageDigest = newMessageDigest();
              messageDigest.update(concatenated);
      
              return messageDigest.digest();
          }
      
          /**
           * Starting with the provided {@code leafHash} combined with the provided {@code internalHashes}
           * pairwise until only the root hash remains.
           *
           * @param internalHashes
           *              Internal hashes of Merkle tree.
           * @param leafHash
           *              Leaf hashes of Merkle tree.
           * @return the root hash.
           */
          private static byte[] calculateRootHashFromInternalHashes(final List<byte[]> internalHashes, final byte[] leafHash) {
              return internalHashes.stream().reduce(leafHash, Verifier::dot);
          }
      
          /**
           * Flip a single random bit in the given byte array. This method is used to demonstrate
           * QLDB's verification features.
           *
           * @param original
           *              The original byte array.
           * @return the altered byte array with a single random bit changed.
           */
          public static byte[] flipRandomBit(final byte[] original) {
              if (original.length == 0) {
                  throw new IllegalArgumentException("Array cannot be empty!");
              }
              int alteredPosition = ThreadLocalRandom.current().nextInt(original.length);
              int b = ThreadLocalRandom.current().nextInt(UPPER_BOUND);
              byte[] altered = new byte[original.length];
              System.arraycopy(original, 0, altered, 0, original.length);
              altered[alteredPosition] = (byte) (altered[alteredPosition] ^ (1 << b));
              return altered;
          }
      
          public static String toBase64(byte[] arr) {
              return new String(Base64.encode(arr), StandardCharsets.UTF_8);
          }
      
          /**
           * Convert a {@link ByteBuffer} into byte array.
           *
           * @param buffer
           *              The {@link ByteBuffer} to convert.
           * @return the converted byte array.
           */
          public static byte[] convertByteBufferToByteArray(final ByteBuffer buffer) {
              byte[] arr = new byte[buffer.remaining()];
              buffer.get(arr);
              return arr;
          }
      
          /**
           * Calculates the root hash from a list of hashes that represent the base of a Merkle tree.
           *
           * @param hashes
           *              The list of byte arrays representing hashes making up base of a Merkle tree.
           * @return a byte array that is the root hash of the given list of hashes.
           */
          public static byte[] calculateMerkleTreeRootHash(List<byte[]> hashes) {
              if (hashes.isEmpty()) {
                  return new byte[0];
              }
      
              List<byte[]> remaining = combineLeafHashes(hashes);
              while (remaining.size() > 1) {
                  remaining = combineLeafHashes(remaining);
              }
              return remaining.get(0);
          }
      
          private static List<byte[]> combineLeafHashes(List<byte[]> hashes) {
              List<byte[]> combinedHashes = new ArrayList<>();
              Iterator<byte[]> it = hashes.stream().iterator();
      
              while (it.hasNext()) {
                  byte[] left = it.next();
                  if (it.hasNext()) {
                      byte[] right = it.next();
                      byte[] combined = dot(left, right);
                      combinedHashes.add(combined);
                  } else {
                      combinedHashes.add(left);
                  }
              }
      
              return combinedHashes;
          }
      }
      ```

------

1. Verwenden Sie zwei `.java` Dateien (`GetDigest.java`und`GetRevision.java`), um die folgenden Schritte durchzuführen:
   + Fordern Sie einen neuen Digest aus dem Ledger `vehicle-registration` an.
   + Fordern Sie einen Nachweis für jede Revision eines Dokuments aus der `VehicleRegistration`-Tabelle an.
   + Überprüfen Sie die Revisionen mit dem zurückgegebenen Digest und dem Nachweis, indem Sie den Digest neu berechnen.

   Das Programm `GetDigest.java` enthält den folgenden Code.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.model.GetDigestRequest;
   import com.amazonaws.services.qldb.model.GetDigestResult;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.tutorial.qldb.QldbStringUtils;
   
   /**
    * This is an example for retrieving the digest of a particular ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class GetDigest {
       public static final Logger log = LoggerFactory.getLogger(GetDigest.class);
       public static AmazonQLDB client = CreateLedger.getClient();
   
       private GetDigest() { }
   
       /**
        * Calls {@link #getDigest(String)} for a ledger.
        *
        * @param args
        *              Arbitrary command-line arguments.
        * @throws Exception if failed to get a ledger digest.
        */
       public static void main(final String... args) throws Exception {
           try {
   
               getDigest(Constants.LEDGER_NAME);
   
           } catch (Exception e) {
               log.error("Unable to get a ledger digest!", e);
               throw e;
           }
       }
   
       /**
        * Get the digest for the specified ledger.
        *
        * @param ledgerName
        *              The ledger to get digest from.
        * @return {@link GetDigestResult}.
        */
       public static GetDigestResult getDigest(final String ledgerName) {
           log.info("Let's get the current digest of the ledger named {}.", ledgerName);
           GetDigestRequest request = new GetDigestRequest()
                   .withName(ledgerName);
           GetDigestResult result = client.getDigest(request);
           log.info("Success. LedgerDigest: {}.", QldbStringUtils.toUnredactedString(result));
           return result;
       }
   }
   ```
**Anmerkung**  
Verwenden Sie die `getDigest`-Methode, um einen Digest anzufordern, der die aktuelle *Spitze* des Journal in Ihrem Ledger abdeckt. Der Tipp des Journals bezieht sich auf den letzten festgeschriebenen Block zu dem Zeitpunkt, zu dem QLDB Ihre Anfrage erhält.

   Das Programm `GetRevision.java` enthält den folgenden Code.

------
#### [ 2.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonReader;
   import com.amazon.ion.IonStruct;
   import com.amazon.ion.IonSystem;
   import com.amazon.ion.IonValue;
   import com.amazon.ion.IonWriter;
   import com.amazon.ion.system.IonReaderBuilder;
   import com.amazon.ion.system.IonSystemBuilder;
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.model.GetDigestResult;
   import com.amazonaws.services.qldb.model.GetRevisionRequest;
   import com.amazonaws.services.qldb.model.GetRevisionResult;
   import com.amazonaws.services.qldb.model.ValueHolder;
   import java.io.ByteArrayOutputStream;
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.List;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.QldbDriver;
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   import software.amazon.qldb.tutorial.qldb.BlockAddress;
   import software.amazon.qldb.tutorial.qldb.QldbRevision;
   import software.amazon.qldb.tutorial.qldb.QldbStringUtils;
   
   /**
    * Verify the integrity of a document revision in a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class GetRevision {
       public static final Logger log = LoggerFactory.getLogger(GetRevision.class);
       public static AmazonQLDB client = CreateLedger.getClient();
       private static final IonSystem SYSTEM = IonSystemBuilder.standard().build();
   
       private GetRevision() { }
   
       public static void main(String... args) throws Exception {
   
           final String vin = SampleData.REGISTRATIONS.get(0).getVin();
   
   
           verifyRegistration(ConnectToLedger.getDriver(), Constants.LEDGER_NAME, vin);
       }
   
       /**
        * Verify each version of the registration for the given VIN.
        *
        * @param driver
        *              A QLDB driver.
        * @param ledgerName
        *              The ledger to get digest from.
        * @param vin
        *              VIN to query the revision history of a specific registration with.
        * @throws Exception if failed to verify digests.
        * @throws AssertionError if document revision verification failed.
        */
       public static void verifyRegistration(final QldbDriver driver, final String ledgerName, final String vin)
               throws Exception {
           log.info(String.format("Let's verify the registration with VIN=%s, in ledger=%s.", vin, ledgerName));
   
           try {
               log.info("First, let's get a digest.");
               GetDigestResult digestResult = GetDigest.getDigest(ledgerName);
   
               ValueHolder digestTipAddress = digestResult.getDigestTipAddress();
               byte[] digestBytes = Verifier.convertByteBufferToByteArray(digestResult.getDigest());
   
               log.info("Got a ledger digest. Digest end address={}, digest={}.",
                   QldbStringUtils.toUnredactedString(digestTipAddress),
                   Verifier.toBase64(digestBytes));
   
               log.info(String.format("Next, let's query the registration with VIN=%s. "
                       + "Then we can verify each version of the registration.", vin));
               List<IonStruct> documentsWithMetadataList = new ArrayList<>();
               driver.execute(txn -> {
                   documentsWithMetadataList.addAll(queryRegistrationsByVin(txn, vin));
               });
               log.info("Registrations queried successfully!");
   
               log.info(String.format("Found %s revisions of the registration with VIN=%s.",
                       documentsWithMetadataList.size(), vin));
   
               for (IonStruct ionStruct : documentsWithMetadataList) {
   
                   QldbRevision document = QldbRevision.fromIon(ionStruct);
                   log.info(String.format("Let's verify the document: %s", document));
   
                   log.info("Let's get a proof for the document.");
                   GetRevisionResult proofResult = getRevision(
                           ledgerName,
                           document.getMetadata().getId(),
                           digestTipAddress,
                           document.getBlockAddress()
                   );
   
                   final IonValue proof = Constants.MAPPER.writeValueAsIonValue(proofResult.getProof());
                   final IonReader reader = IonReaderBuilder.standard().build(proof);
                   reader.next();
                   ByteArrayOutputStream baos = new ByteArrayOutputStream();
                   IonWriter writer = SYSTEM.newBinaryWriter(baos);
                   writer.writeValue(reader);
                   writer.close();
                   baos.flush();
                   baos.close();
                   byte[] byteProof = baos.toByteArray();
   
                   log.info(String.format("Got back a proof: %s", Verifier.toBase64(byteProof)));
   
                   boolean verified = Verifier.verify(
                           document.getHash(),
                           digestBytes,
                           proofResult.getProof().getIonText()
                   );
   
                   if (!verified) {
                       throw new AssertionError("Document revision is not verified!");
                   } else {
                       log.info("Success! The document is verified");
                   }
   
                   byte[] alteredDigest = Verifier.flipRandomBit(digestBytes);
                   log.info(String.format("Flipping one bit in the digest and assert that the document is NOT verified. "
                           + "The altered digest is: %s", Verifier.toBase64(alteredDigest)));
                   verified = Verifier.verify(
                           document.getHash(),
                           alteredDigest,
                           proofResult.getProof().getIonText()
                   );
   
                   if (verified) {
                       throw new AssertionError("Expected document to not be verified against altered digest.");
                   } else {
                       log.info("Success! As expected flipping a bit in the digest causes verification to fail.");
                   }
   
                   byte[] alteredDocumentHash = Verifier.flipRandomBit(document.getHash());
                   log.info(String.format("Flipping one bit in the document's hash and assert that it is NOT verified. "
                           + "The altered document hash is: %s.", Verifier.toBase64(alteredDocumentHash)));
                   verified = Verifier.verify(
                           alteredDocumentHash,
                           digestBytes,
                           proofResult.getProof().getIonText()
                   );
   
                   if (verified) {
                       throw new AssertionError("Expected altered document hash to not be verified against digest.");
                   } else {
                       log.info("Success! As expected flipping a bit in the document hash causes verification to fail.");
                   }
               }
   
           } catch (Exception e) {
               log.error("Failed to verify digests.", e);
               throw e;
           }
   
           log.info(String.format("Finished verifying the registration with VIN=%s in ledger=%s.", vin, ledgerName));
       }
   
       /**
        * Get the revision of a particular document specified by the given document ID and block address.
        *
        * @param ledgerName
        *              Name of the ledger containing the document.
        * @param documentId
        *              Unique ID for the document to be verified, contained in the committed view of the document.
        * @param digestTipAddress
        *              The latest block location covered by the digest.
        * @param blockAddress
        *              The location of the block to request.
        * @return the requested revision.
        */
       public static GetRevisionResult getRevision(final String ledgerName, final String documentId,
                                                   final ValueHolder digestTipAddress, final BlockAddress blockAddress) {
           try {
               GetRevisionRequest request = new GetRevisionRequest()
                       .withName(ledgerName)
                       .withDigestTipAddress(digestTipAddress)
                       .withBlockAddress(new ValueHolder().withIonText(Constants.MAPPER.writeValueAsIonValue(blockAddress)
                               .toString()))
                       .withDocumentId(documentId);
               return client.getRevision(request);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Query the registration history for the given VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              The unique VIN to query.
        * @return a list of {@link IonStruct} representing the registration history.
        * @throws IllegalStateException if failed to convert parameters into {@link IonValue}
        */
       public static List<IonStruct> queryRegistrationsByVin(final TransactionExecutor txn, final String vin) {
           log.info(String.format("Let's query the 'VehicleRegistration' table for VIN: %s...", vin));
           log.info("Let's query the 'VehicleRegistration' table for VIN: {}...", vin);
           final String query = String.format("SELECT * FROM _ql_committed_%s WHERE data.VIN = ?",
                   Constants.VEHICLE_REGISTRATION_TABLE_NAME);
           try {
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
               final Result result = txn.execute(query, parameters);
               List<IonStruct> list = ScanTable.toIonStructs(result);
               log.info(String.format("Found %d document(s)!", list.size()));
               return list;
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   }
   ```

------
#### [ 1.x ]

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazon.ion.IonReader;
   import com.amazon.ion.IonStruct;
   import com.amazon.ion.IonValue;
   import com.amazon.ion.IonWriter;
   import com.amazon.ion.system.IonReaderBuilder;
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.model.GetDigestResult;
   import com.amazonaws.services.qldb.model.GetRevisionRequest;
   import com.amazonaws.services.qldb.model.GetRevisionResult;
   import com.amazonaws.services.qldb.model.ValueHolder;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.QldbSession;
   import software.amazon.qldb.Result;
   import software.amazon.qldb.TransactionExecutor;
   import software.amazon.qldb.tutorial.model.SampleData;
   import software.amazon.qldb.tutorial.qldb.BlockAddress;
   import software.amazon.qldb.tutorial.qldb.QldbRevision;
   import software.amazon.qldb.tutorial.qldb.QldbStringUtils;
   
   import java.io.ByteArrayOutputStream;
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.Collections;
   import java.util.List;
   
   /**
    * Verify the integrity of a document revision in a QLDB ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class GetRevision {
       public static final Logger log = LoggerFactory.getLogger(GetRevision.class);
       public static AmazonQLDB client = CreateLedger.getClient();
   
       private GetRevision() { }
   
       public static void main(String... args) throws Exception {
   
           final String vin = SampleData.REGISTRATIONS.get(0).getVin();
   
           try (QldbSession qldbSession = ConnectToLedger.createQldbSession()) {
               verifyRegistration(qldbSession, Constants.LEDGER_NAME, vin);
           }
       }
   
       /**
        * Verify each version of the registration for the given VIN.
        *
        * @param qldbSession
        *              A QLDB session.
        * @param ledgerName
        *              The ledger to get digest from.
        * @param vin
        *              VIN to query the revision history of a specific registration with.
        * @throws Exception if failed to verify digests.
        * @throws AssertionError if document revision verification failed.
        */
       public static void verifyRegistration(final QldbSession qldbSession, final String ledgerName, final String vin)
               throws Exception {
           log.info(String.format("Let's verify the registration with VIN=%s, in ledger=%s.", vin, ledgerName));
   
           try {
               log.info("First, let's get a digest.");
               GetDigestResult digestResult = GetDigest.getDigest(ledgerName);
   
               ValueHolder digestTipAddress = digestResult.getDigestTipAddress();
               byte[] digestBytes = Verifier.convertByteBufferToByteArray(digestResult.getDigest());
   
               log.info("Got a ledger digest. Digest end address={}, digest={}.",
                   QldbStringUtils.toUnredactedString(digestTipAddress),
                   Verifier.toBase64(digestBytes));
   
               log.info(String.format("Next, let's query the registration with VIN=%s. "
                       + "Then we can verify each version of the registration.", vin));
               List<IonStruct> documentsWithMetadataList = new ArrayList<>();
               qldbSession.execute(txn -> {
                   documentsWithMetadataList.addAll(queryRegistrationsByVin(txn, vin));
               }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
               log.info("Registrations queried successfully!");
   
               log.info(String.format("Found %s revisions of the registration with VIN=%s.",
                       documentsWithMetadataList.size(), vin));
   
               for (IonStruct ionStruct : documentsWithMetadataList) {
   
                   QldbRevision document = QldbRevision.fromIon(ionStruct);
                   log.info(String.format("Let's verify the document: %s", document));
   
                   log.info("Let's get a proof for the document.");
                   GetRevisionResult proofResult = getRevision(
                           ledgerName,
                           document.getMetadata().getId(),
                           digestTipAddress,
                           document.getBlockAddress()
                   );
   
                   final IonValue proof = Constants.MAPPER.writeValueAsIonValue(proofResult.getProof());
                   final IonReader reader = IonReaderBuilder.standard().build(proof);
                   reader.next();
                   ByteArrayOutputStream baos = new ByteArrayOutputStream();
                   IonWriter writer = Constants.SYSTEM.newBinaryWriter(baos);
                   writer.writeValue(reader);
                   writer.close();
                   baos.flush();
                   baos.close();
                   byte[] byteProof = baos.toByteArray();
   
                   log.info(String.format("Got back a proof: %s", Verifier.toBase64(byteProof)));
   
                   boolean verified = Verifier.verify(
                           document.getHash(),
                           digestBytes,
                           proofResult.getProof().getIonText()
                   );
   
                   if (!verified) {
                       throw new AssertionError("Document revision is not verified!");
                   } else {
                       log.info("Success! The document is verified");
                   }
   
                   byte[] alteredDigest = Verifier.flipRandomBit(digestBytes);
                   log.info(String.format("Flipping one bit in the digest and assert that the document is NOT verified. "
                           + "The altered digest is: %s", Verifier.toBase64(alteredDigest)));
                   verified = Verifier.verify(
                           document.getHash(),
                           alteredDigest,
                           proofResult.getProof().getIonText()
                   );
   
                   if (verified) {
                       throw new AssertionError("Expected document to not be verified against altered digest.");
                   } else {
                       log.info("Success! As expected flipping a bit in the digest causes verification to fail.");
                   }
   
                   byte[] alteredDocumentHash = Verifier.flipRandomBit(document.getHash());
                   log.info(String.format("Flipping one bit in the document's hash and assert that it is NOT verified. "
                           + "The altered document hash is: %s.", Verifier.toBase64(alteredDocumentHash)));
                   verified = Verifier.verify(
                           alteredDocumentHash,
                           digestBytes,
                           proofResult.getProof().getIonText()
                   );
   
                   if (verified) {
                       throw new AssertionError("Expected altered document hash to not be verified against digest.");
                   } else {
                       log.info("Success! As expected flipping a bit in the document hash causes verification to fail.");
                   }
               }
   
           } catch (Exception e) {
               log.error("Failed to verify digests.", e);
               throw e;
           }
   
           log.info(String.format("Finished verifying the registration with VIN=%s in ledger=%s.", vin, ledgerName));
       }
   
       /**
        * Get the revision of a particular document specified by the given document ID and block address.
        *
        * @param ledgerName
        *              Name of the ledger containing the document.
        * @param documentId
        *              Unique ID for the document to be verified, contained in the committed view of the document.
        * @param digestTipAddress
        *              The latest block location covered by the digest.
        * @param blockAddress
        *              The location of the block to request.
        * @return the requested revision.
        */
       public static GetRevisionResult getRevision(final String ledgerName, final String documentId,
                                                   final ValueHolder digestTipAddress, final BlockAddress blockAddress) {
           try {
               GetRevisionRequest request = new GetRevisionRequest()
                       .withName(ledgerName)
                       .withDigestTipAddress(digestTipAddress)
                       .withBlockAddress(new ValueHolder().withIonText(Constants.MAPPER.writeValueAsIonValue(blockAddress)
                               .toString()))
                       .withDocumentId(documentId);
               return client.getRevision(request);
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   
       /**
        * Query the registration history for the given VIN.
        *
        * @param txn
        *              The {@link TransactionExecutor} for lambda execute.
        * @param vin
        *              The unique VIN to query.
        * @return a list of {@link IonStruct} representing the registration history.
        * @throws IllegalStateException if failed to convert parameters into {@link IonValue}
        */
       public static List<IonStruct> queryRegistrationsByVin(final TransactionExecutor txn, final String vin) {
           log.info(String.format("Let's query the 'VehicleRegistration' table for VIN: %s...", vin));
           log.info("Let's query the 'VehicleRegistration' table for VIN: {}...", vin);
           final String query = String.format("SELECT * FROM _ql_committed_%s WHERE data.VIN = ?",
                   Constants.VEHICLE_REGISTRATION_TABLE_NAME);
           try {
               final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(vin));
               final Result result = txn.execute(query, parameters);
               List<IonStruct> list = ScanTable.toIonStructs(result);
               log.info(String.format("Found %d document(s)!", list.size()));
               return list;
           } catch (IOException ioe) {
               throw new IllegalStateException(ioe);
           }
       }
   }
   ```

------
**Anmerkung**  
Nachdem die `getRevision`-Methode einen Nachweis für die angegebene Dokumentrevision zurückgibt, verwendet dieses Programm eine clientseitige API, um diese Revision zu überprüfen. Eine Übersicht über den Algorithmus, der von dieser API verwendet wird, finden Sie unter [Verwenden Sie einen Nachweis, um Ihren Digest neu zu berechnen](verification.results.md#verification.results.recalc).

1. Kompilieren Sie das `GetRevision.java`-Programm und führen Sie es aus, um das `VehicleRegistration`-Dokument kryptografisch mit VIN `1N4AL11D75C109151` zu überprüfen.

Um Journaldaten im `vehicle-registration` Ledger zu exportieren und zu validieren, fahren Sie mit fort. [Schritt 8: Exportieren und validieren Sie Journaldaten in einem Ledger](getting-started.java.step-8.md)

# Schritt 8: Exportieren und validieren Sie Journaldaten in einem Ledger
<a name="getting-started.java.step-8"></a>

**Wichtig**  
Hinweis zum Ende des Supports: Bestandskunden können Amazon QLDB bis zum Ende des Supports am 31.07.2025 nutzen. Weitere Informationen finden Sie unter [Migrieren eines Amazon QLDB-Ledgers zu Amazon](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/) Aurora PostgreSQL.

In Amazon QLDB können Sie für verschiedene Zwecke wie Datenspeicherung, Analyse und Prüfung auf den Inhalt des Journals in Ihrem Hauptbuch zugreifen. Weitere Informationen finden Sie unter [Journaldaten aus Amazon QLDB exportieren](export-journal.md).

In diesem Schritt exportieren Sie [Journalblöcke](journal-contents.md) aus dem `vehicle-registration` Ledger in einen Amazon S3 S3-Bucket. Anschließend verwenden Sie die exportierten Daten, um die Hash-Kette zwischen Journalblöcken und den einzelnen Hash-Komponenten innerhalb jedes Blocks zu validieren.

Die AWS Identity and Access Management (IAM-) Prinzipalentität, die Sie verwenden, muss über ausreichende IAM-Berechtigungen verfügen, um einen Amazon S3 S3-Bucket in Ihrem zu erstellen. AWS-Konto Weitere Informationen finden Sie unter [Richtlinien und Berechtigungen in Amazon S3](https://docs.aws.amazon.com/AmazonS3/latest/userguide/access-policy-language-overview.html) im *Amazon S3 S3-Benutzerhandbuch*. Sie benötigen außerdem die erforderlichen Berechtigungen, um eine IAM-Rolle mit einer angehängten Berechtigungsrichtlinie zu erstellen, die es QLDB ermöglicht, Objekte in Ihren Amazon S3 S3-Bucket zu schreiben. *Weitere Informationen finden Sie unter Für den [Zugriff auf IAM-Ressourcen erforderliche Berechtigungen im IAM-Benutzerhandbuch](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_permissions-required.html).*

**Um Journaldaten zu exportieren und zu validieren**

1. Überprüfen Sie die folgende Datei (`JournalBlock.java`), die einen Journalblock und seinen Dateninhalt darstellt. Sie enthält eine Methode mit dem Namen`verifyBlockHash()`, die demonstriert, wie jede einzelne Komponente eines Block-Hashes berechnet wird.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial.qldb;
   
   import com.fasterxml.jackson.annotation.JsonCreator;
   import com.fasterxml.jackson.annotation.JsonProperty;
   import com.fasterxml.jackson.databind.annotation.JsonSerialize;
   import com.fasterxml.jackson.dataformat.ion.IonTimestampSerializers;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   import software.amazon.qldb.tutorial.Constants;
   import software.amazon.qldb.tutorial.Verifier;
   
   import java.io.IOException;
   import java.nio.ByteBuffer;
   import java.util.Arrays;
   import java.util.Date;
   import java.util.HashSet;
   import java.util.List;
   import java.util.Set;
   import java.util.stream.Collectors;
   
   import static java.nio.ByteBuffer.wrap;
   
   /**
    * Represents a JournalBlock that was recorded after executing a transaction
    * in the ledger.
    */
   public final class JournalBlock {
       private static final Logger log = LoggerFactory.getLogger(JournalBlock.class);
   
       private BlockAddress blockAddress;
       private String transactionId;
       @JsonSerialize(using = IonTimestampSerializers.IonTimestampJavaDateSerializer.class)
       private Date blockTimestamp;
       private byte[] blockHash;
       private byte[] entriesHash;
       private byte[] previousBlockHash;
       private byte[][] entriesHashList;
       private TransactionInfo transactionInfo;
       private RedactionInfo redactionInfo;
       private List<QldbRevision> revisions;
   
       @JsonCreator
       public JournalBlock(@JsonProperty("blockAddress") final BlockAddress blockAddress,
                           @JsonProperty("transactionId") final String transactionId,
                           @JsonProperty("blockTimestamp") final Date blockTimestamp,
                           @JsonProperty("blockHash") final byte[] blockHash,
                           @JsonProperty("entriesHash") final byte[] entriesHash,
                           @JsonProperty("previousBlockHash") final byte[] previousBlockHash,
                           @JsonProperty("entriesHashList") final byte[][] entriesHashList,
                           @JsonProperty("transactionInfo") final TransactionInfo transactionInfo,
                           @JsonProperty("redactionInfo") final RedactionInfo redactionInfo,
                           @JsonProperty("revisions") final List<QldbRevision> revisions) {
           this.blockAddress = blockAddress;
           this.transactionId = transactionId;
           this.blockTimestamp = blockTimestamp;
           this.blockHash = blockHash;
           this.entriesHash = entriesHash;
           this.previousBlockHash = previousBlockHash;
           this.entriesHashList = entriesHashList;
           this.transactionInfo = transactionInfo;
           this.redactionInfo = redactionInfo;
           this.revisions = revisions;
       }
   
       public BlockAddress getBlockAddress() {
           return blockAddress;
       }
   
       public String getTransactionId() {
           return transactionId;
       }
   
       public Date getBlockTimestamp() {
           return blockTimestamp;
       }
   
       public byte[][] getEntriesHashList() {
           return entriesHashList;
       }
   
       public TransactionInfo getTransactionInfo() {
           return transactionInfo;
       }
   
       public RedactionInfo getRedactionInfo() {
           return redactionInfo;
       }
   
       public List<QldbRevision> getRevisions() {
           return revisions;
       }
   
       public byte[] getEntriesHash() {
           return entriesHash;
       }
   
       public byte[] getBlockHash() {
           return blockHash;
       }
   
       public byte[] getPreviousBlockHash() {
           return previousBlockHash;
       }
   
       @Override
       public String toString() {
           return "JournalBlock{"
                   + "blockAddress=" + blockAddress
                   + ", transactionId='" + transactionId + '\''
                   + ", blockTimestamp=" + blockTimestamp
                   + ", blockHash=" + Arrays.toString(blockHash)
                   + ", entriesHash=" + Arrays.toString(entriesHash)
                   + ", previousBlockHash=" + Arrays.toString(previousBlockHash)
                   + ", entriesHashList=" + Arrays.toString(entriesHashList)
                   + ", transactionInfo=" + transactionInfo
                   + ", redactionInfo=" + redactionInfo
                   + ", revisions=" + revisions
                   + '}';
       }
   
       @Override
       public boolean equals(final Object o) {
           if (this == o) {
               return true;
           }
           if (!(o instanceof JournalBlock)) {
               return false;
           }
   
           final JournalBlock that = (JournalBlock) o;
   
           if (!getBlockAddress().equals(that.getBlockAddress())) {
               return false;
           }
           if (!getTransactionId().equals(that.getTransactionId())) {
               return false;
           }
           if (!getBlockTimestamp().equals(that.getBlockTimestamp())) {
               return false;
           }
           if (!Arrays.equals(getBlockHash(), that.getBlockHash())) {
               return false;
           }
           if (!Arrays.equals(getEntriesHash(), that.getEntriesHash())) {
               return false;
           }
           if (!Arrays.equals(getPreviousBlockHash(), that.getPreviousBlockHash())) {
               return false;
           }
           if (!Arrays.deepEquals(getEntriesHashList(), that.getEntriesHashList())) {
               return false;
           }
           if (!getTransactionInfo().equals(that.getTransactionInfo())) {
               return false;
           }
           if (getRedactionInfo() != null ? !getRedactionInfo().equals(that.getRedactionInfo()) : that.getRedactionInfo() != null) {
               return false;
           }
           return getRevisions() != null ? getRevisions().equals(that.getRevisions()) : that.getRevisions() == null;
       }
   
       @Override
       public int hashCode() {
           int result = getBlockAddress().hashCode();
           result = 31 * result + getTransactionId().hashCode();
           result = 31 * result + getBlockTimestamp().hashCode();
           result = 31 * result + Arrays.hashCode(getBlockHash());
           result = 31 * result + Arrays.hashCode(getEntriesHash());
           result = 31 * result + Arrays.hashCode(getPreviousBlockHash());
           result = 31 * result + Arrays.deepHashCode(getEntriesHashList());
           result = 31 * result + getTransactionInfo().hashCode();
           result = 31 * result + (getRedactionInfo() != null ? getRedactionInfo().hashCode() : 0);
           result = 31 * result + (getRevisions() != null ? getRevisions().hashCode() : 0);
           return result;
       }
   
       /**
        * This method validates that the hashes of the components of a journal block make up the block
        * hash that is provided with the block itself.
        *
        * The components that contribute to the hash of the journal block consist of the following:
        *   - user transaction information (contained in [transactionInfo])
        *   - user redaction information (contained in [redactionInfo])
        *   - user revisions (contained in [revisions])
        *   - hashes of internal-only system metadata (contained in [revisions] and in [entriesHashList])
        *   - the previous block hash
        *
        * If any of the computed hashes of user information cannot be validated or any of the system
        * hashes do not result in the correct computed values, this method will throw an IllegalArgumentException.
        *
        * Internal-only system metadata is represented by its hash, and can be present in the form of certain
        * items in the [revisions] list that only contain a hash and no user data, as well as some hashes
        * in [entriesHashList].
        *
        * To validate that the hashes of the user data are valid components of the [blockHash], this method
        * performs the following steps:
        *
        * 1. Compute the hash of the [transactionInfo] and validate that it is included in the [entriesHashList].
        * 2. Compute the hash of the [redactionInfo], if present, and validate that it is included in the [entriesHashList].
        * 3. Validate the hash of each user revision was correctly computed and matches the hash published
        * with that revision.
        * 4. Compute the hash of the [revisions] by treating the revision hashes as the leaf nodes of a Merkle tree
        * and calculating the root hash of that tree. Then validate that hash is included in the [entriesHashList].
        * 5. Compute the hash of the [entriesHashList] by treating the hashes as the leaf nodes of a Merkle tree
        * and calculating the root hash of that tree. Then validate that hash matches [entriesHash].
        * 6. Finally, compute the block hash by computing the hash resulting from concatenating the [entriesHash]
        * and previous block hash, and validate that the result matches the [blockHash] provided by QLDB with the block.
        *
        * This method is called by ValidateQldbHashChain::verify for each journal block to validate its
        * contents before verifying that the hash chain between consecutive blocks is correct.
        */
       public void verifyBlockHash() {
           Set<ByteBuffer> entriesHashSet = new HashSet<>();
           Arrays.stream(entriesHashList).forEach(hash -> entriesHashSet.add(wrap(hash).asReadOnlyBuffer()));
   
           byte[] computedTransactionInfoHash = computeTransactionInfoHash();
           if (!entriesHashSet.contains(wrap(computedTransactionInfoHash).asReadOnlyBuffer())) {
               throw new IllegalArgumentException(
                       "Block transactionInfo hash is not contained in the QLDB block entries hash list.");
           }
   
           if (redactionInfo != null) {
               byte[] computedRedactionInfoHash = computeRedactionInfoHash();
               if (!entriesHashSet.contains(wrap(computedRedactionInfoHash).asReadOnlyBuffer())) {
                   throw new IllegalArgumentException(
                           "Block redactionInfo hash is not contained in the QLDB block entries hash list.");
               }
           }
   
           if (revisions != null) {
               revisions.forEach(QldbRevision::verifyRevisionHash);
               byte[] computedRevisionsHash = computeRevisionsHash();
               if (!entriesHashSet.contains(wrap(computedRevisionsHash).asReadOnlyBuffer())) {
                   throw new IllegalArgumentException(
                           "Block revisions list hash is not contained in the QLDB block entries hash list.");
               }
           }
   
           byte[] computedEntriesHash = computeEntriesHash();
           if (!Arrays.equals(computedEntriesHash, entriesHash)) {
               throw new IllegalArgumentException("Computed entries hash does not match entries hash provided in the block.");
           }
   
           byte[] computedBlockHash = Verifier.dot(computedEntriesHash, previousBlockHash);
           if (!Arrays.equals(computedBlockHash, blockHash)) {
               throw new IllegalArgumentException("Computed block hash does not match block hash provided in the block.");
           }
       }
   
       private byte[] computeTransactionInfoHash() {
           try {
               return QldbIonUtils.hashIonValue(Constants.MAPPER.writeValueAsIonValue(transactionInfo));
           } catch (IOException e) {
               throw new IllegalArgumentException("Could not compute transactionInfo hash to verify block hash.", e);
           }
       }
   
       private byte[] computeRedactionInfoHash() {
           try {
               return QldbIonUtils.hashIonValue(Constants.MAPPER.writeValueAsIonValue(redactionInfo));
           } catch (IOException e) {
               throw new IllegalArgumentException("Could not compute redactionInfo hash to verify block hash.", e);
           }
       }
   
       private byte[] computeRevisionsHash() {
           return Verifier.calculateMerkleTreeRootHash(revisions.stream().map(QldbRevision::getHash).collect(Collectors.toList()));
       }
   
       private byte[] computeEntriesHash() {
           return Verifier.calculateMerkleTreeRootHash(Arrays.asList(entriesHashList));
       }
   }
   ```

1. Kompilieren Sie das folgende Programm (`ValidateQldbHashChain.java`) und führen Sie es aus, um die folgenden Schritte auszuführen:

   1. Exportieren Sie Journalblöcke aus dem `vehicle-registration` Ledger in einen Amazon S3 S3-Bucket mit dem Namen **qldb-tutorial-journal-export-*111122223333*** (ersetzen Sie durch Ihre AWS-Konto Nummer).

   1. Überprüfen Sie die einzelnen Hash-Komponenten innerhalb jedes Blocks, indem Sie aufrufen`verifyBlockHash()`.

   1. Validieren Sie die Hash-Kette zwischen Journalblöcken.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.services.qldb.model.ExportJournalToS3Result;
   import com.amazonaws.services.qldb.model.S3EncryptionConfiguration;
   import com.amazonaws.services.qldb.model.S3ObjectEncryptionType;
   import com.amazonaws.services.s3.AmazonS3ClientBuilder;
   
   import java.time.Instant;
   import java.util.Arrays;
   import java.util.List;
   
   import com.amazonaws.services.securitytoken.AWSSecurityTokenServiceClientBuilder;
   import com.amazonaws.services.securitytoken.model.GetCallerIdentityRequest;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   import software.amazon.qldb.tutorial.qldb.JournalBlock;
   
   /**
    * Validate the hash chain of a QLDB ledger by stepping through its S3 export.
    *
    * This code accepts an exportId as an argument, if exportId is passed the code
    * will use that or request QLDB to generate a new export to perform QLDB hash
    * chain validation.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class ValidateQldbHashChain {
       public static final Logger log = LoggerFactory.getLogger(ValidateQldbHashChain.class);
       private static final int TIME_SKEW = 20;
   
       private ValidateQldbHashChain() { }
   
       /**
        * Export journal contents to a S3 bucket.
        *
        * @return the ExportId of the journal export.
        * @throws InterruptedException if the thread is interrupted while waiting for export to complete.
        */
       private static String createExport() throws InterruptedException {
           String accountId = AWSSecurityTokenServiceClientBuilder.defaultClient()
               .getCallerIdentity(new GetCallerIdentityRequest()).getAccount();
           String bucketName = Constants.JOURNAL_EXPORT_S3_BUCKET_NAME_PREFIX + "-" + accountId;
           String prefix = Constants.LEDGER_NAME + "-" + Instant.now().getEpochSecond() + "/";
   
           S3EncryptionConfiguration encryptionConfiguration = new S3EncryptionConfiguration()
                   .withObjectEncryptionType(S3ObjectEncryptionType.SSE_S3);
           ExportJournalToS3Result exportJournalToS3Result = 
               ExportJournal.createJournalExportAndAwaitCompletion(Constants.LEDGER_NAME, 
                       bucketName, prefix, null, encryptionConfiguration, ExportJournal.DEFAULT_EXPORT_TIMEOUT_MS);
   
           return exportJournalToS3Result.getExportId();
       }
   
       /**
        * Validates that the chain hash on the {@link JournalBlock} is valid.
        *
        * @param journalBlocks
        *              {@link JournalBlock} containing hashes to validate.
        * @throws IllegalStateException if previous block hash does not match.
        */
       public static void verify(final List<JournalBlock> journalBlocks) {
           if (journalBlocks.size() == 0) {
               return;
           }
   
           journalBlocks.stream().reduce(null, (previousJournalBlock, journalBlock) -> {
               journalBlock.verifyBlockHash();
               if (previousJournalBlock == null) { return journalBlock; }
               if (!Arrays.equals(previousJournalBlock.getBlockHash(), journalBlock.getPreviousBlockHash())) {
                   throw new IllegalStateException("Previous block hash doesn't match.");
               }
               byte[] blockHash = Verifier.dot(journalBlock.getEntriesHash(), previousJournalBlock.getBlockHash());
               if (!Arrays.equals(blockHash, journalBlock.getBlockHash())) {
                   throw new IllegalStateException("Block hash doesn't match entriesHash dot previousBlockHash, the chain is "
                           + "broken.");
               }
               return journalBlock;
           });
       }
   
       public static void main(final String... args) throws InterruptedException {
           try {
               String exportId;
               if (args.length == 1) {
                   exportId = args[0];
                   log.info("Validating QLDB hash chain for exportId: " + exportId);
               } else {
                   log.info("Requesting QLDB to create an export.");
                   exportId = createExport();
               }
               List<JournalBlock> journalBlocks =
                   JournalS3ExportReader.readExport(DescribeJournalExport.describeExport(Constants.LEDGER_NAME,
                       exportId), AmazonS3ClientBuilder.defaultClient());
               verify(journalBlocks);
           } catch (Exception e) {
               log.error("Unable to perform hash chain verification.", e);
               throw e;
           }
       }
   
   }
   ```

Wenn Sie den `vehicle-registration`-Ledger nicht mehr verwenden müssen, fahren Sie mit [Schritt 9 (optional): Ressourcen bereinigen](getting-started.java.step-9.md) fort.

# Schritt 9 (optional): Ressourcen bereinigen
<a name="getting-started.java.step-9"></a>

**Wichtig**  
Hinweis zum Ende des Supports: Bestandskunden können Amazon QLDB bis zum Ende des Supports am 31.07.2025 nutzen. Weitere Informationen finden Sie unter [Migrieren eines Amazon QLDB-Ledgers zu Amazon](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/) Aurora PostgreSQL.

Sie können den `vehicle-registration`-Ledger weiterhin verwenden. Wenn Sie ihn nicht mehr benötigen, sollten Sie ihn jedoch löschen.

**So löschen Sie den Ledger**

1. Kompilieren Sie das folgende Programm (`DeleteLedger.java`) und führen Sie es aus, um Ihren `vehicle-registration`-Ledger und seinen gesamten Inhalt zu löschen.

   ```
   /*
    * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
    * SPDX-License-Identifier: MIT-0
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy of this
    * software and associated documentation files (the "Software"), to deal in the Software
    * without restriction, including without limitation the rights to use, copy, modify,
    * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
    * permit persons to whom the Software is furnished to do so.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
    * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
    * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
   
   package software.amazon.qldb.tutorial;
   
   import com.amazonaws.services.qldb.AmazonQLDB;
   import com.amazonaws.services.qldb.model.DeleteLedgerRequest;
   import com.amazonaws.services.qldb.model.DeleteLedgerResult;
   import com.amazonaws.services.qldb.model.ResourceNotFoundException;
   import com.amazonaws.services.qldb.model.UpdateLedgerRequest;
   import com.amazonaws.services.qldb.model.UpdateLedgerResult;
   
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   /**
    * Delete a ledger.
    *
    * This code expects that you have AWS credentials setup per:
    * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
    */
   public final class DeleteLedger {
       public static final Logger log = LoggerFactory.getLogger(DeleteLedger.class);
       public static final Long LEDGER_DELETION_POLL_PERIOD_MS = 20_000L;
       public static AmazonQLDB client = CreateLedger.getClient();
   
       private DeleteLedger() { }
   
       public static void main(String... args) throws Exception {
           try {
               setDeletionProtection(Constants.LEDGER_NAME, false);
   
               delete(Constants.LEDGER_NAME);
   
               waitForDeleted(Constants.LEDGER_NAME);
   
           } catch (Exception e) {
               log.error("Unable to delete the ledger.", e);
               throw e;
           }
       }
   
       /**
        * Send a request to the QLDB database to delete the specified ledger.
        *
        * @param ledgerName
        *              Name of the ledger to be deleted.
        * @return DeleteLedgerResult.
        */
       public static DeleteLedgerResult delete(final String ledgerName) {
           log.info("Attempting to delete the ledger with name: {}...", ledgerName);
           DeleteLedgerRequest request = new DeleteLedgerRequest().withName(ledgerName);
           DeleteLedgerResult result = client.deleteLedger(request);
           log.info("Success.");
           return result;
       }
   
       /**
        * Wait for the ledger to be deleted.
        *
        * @param ledgerName
        *              Name of the ledger being deleted.
        * @throws InterruptedException if thread is being interrupted.
        */
       public static void waitForDeleted(final String ledgerName) throws InterruptedException {
           log.info("Waiting for the ledger to be deleted...");
           while (true) {
               try {
                   DescribeLedger.describe(ledgerName);
                   log.info("The ledger is still being deleted. Please wait...");
                   Thread.sleep(LEDGER_DELETION_POLL_PERIOD_MS);
               } catch (ResourceNotFoundException ex) {
                   log.info("Success. The ledger is deleted.");
                   break;
               }
           }
       }
       
       public static UpdateLedgerResult setDeletionProtection(String ledgerName, boolean deletionProtection) {
           log.info("Let's set deletionProtection to {} for the ledger with name {}", deletionProtection, ledgerName);
           UpdateLedgerRequest request = new UpdateLedgerRequest()
                   .withName(ledgerName)
                   .withDeletionProtection(deletionProtection);
   
           UpdateLedgerResult result = client.updateLedger(request);
           log.info("Success. Ledger updated: {}", result);
           return result;
       }
   }
   ```
**Anmerkung**  
Wenn der Löschschutz für Ihr Ledger aktiviert ist, müssen Sie ihn zuerst deaktivieren, bevor Sie das Ledger mithilfe der QLDB-API löschen können.

1. Wenn Sie im [vorherigen Schritt](getting-started.java.step-8.md) Journaldaten exportiert haben und sie nicht mehr benötigen, verwenden Sie die Amazon S3 S3-Konsole, um Ihren S3-Bucket zu löschen.

   Öffnen Sie die Amazon S3 S3-Konsole unter [https://console.aws.amazon.com/s3/](https://console.aws.amazon.com/s3/).