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# 2단계: 원장과의 연결을 테스트
2단계: 연결 테스트

**중요**  
지원 종료 공지: 기존 고객은 07/31/2025에 지원이 종료될 때까지 Amazon QLDB를 사용할 수 있습니다. 자세한 내용은 [Amazon QLDB 원장을 Amazon Aurora PostgreSQL로 마이그레이션](https://aws.amazon.com/blogs/database/migrate-an-amazon-qldb-ledger-to-amazon-aurora-postgresql/)을 참조하세요.

이 단계에서는 트랜잭션 데이터 API 엔드포인트를 사용하여 Amazon QLDB의 `vehicle-registration` 원장에 연결할 수 있는지 확인합니다.

**원장과의 연결을 테스트하려면**

1. 다음 프로그램(`ConnectToLedger.ts`)을 사용하여 `vehicle-registration` 원장에 대한 데이터 세션 연결을 생성합니다.

------
#### [ 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.
    */
   
   import { QldbDriver, RetryConfig  } from "amazon-qldb-driver-nodejs";
   import { ClientConfiguration } from "aws-sdk/clients/qldbsession";
   
   import { LEDGER_NAME } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   
   const qldbDriver: QldbDriver = createQldbDriver();
   
   /**
    * Create a driver for creating sessions.
    * @param ledgerName The name of the ledger to create the driver on.
    * @param serviceConfigurationOptions The configurations for the AWS SDK client that the driver uses.
    * @returns The driver for creating sessions.
    */
   export function createQldbDriver(
       ledgerName: string = LEDGER_NAME,
       serviceConfigurationOptions: ClientConfiguration = {}
   ): QldbDriver {
       const retryLimit = 4;
       const maxConcurrentTransactions = 10;
       //Use driver's default backoff function (and hence, no second parameter provided to RetryConfig)
       const retryConfig: RetryConfig = new RetryConfig(retryLimit);
       const qldbDriver: QldbDriver = new QldbDriver(ledgerName, serviceConfigurationOptions, maxConcurrentTransactions, retryConfig);
       return qldbDriver;
   }
   
   export function getQldbDriver(): QldbDriver {
       return qldbDriver;
   }
   
   /**
    * Connect to a session for a given ledger using default settings.
    * @returns Promise which fulfills with void.
    */
   const main = async function(): Promise<void> {
       try {
           log("Listing table names...");
           const tableNames: string[] = await qldbDriver.getTableNames();
           tableNames.forEach((tableName: string): void => {
               log(tableName);
           });
       } catch (e) {
           error(`Unable to create session: ${e}`);
       }
   }
   
   if (require.main === module) {
       main();
   }
   ```

------
#### [ 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.
    */
   
   import { QldbDriver  } from "amazon-qldb-driver-nodejs";
   import { ClientConfiguration } from "aws-sdk/clients/qldbsession";
   
   import { LEDGER_NAME } from "./qldb/Constants";
   import { error, log } from "./qldb/LogUtil";
   
   const qldbDriver: QldbDriver = createQldbDriver();
   
   /**
    * Create a driver for creating sessions.
    * @param ledgerName The name of the ledger to create the driver on.
    * @param serviceConfigurationOptions The configurations for the AWS SDK client that the driver uses.
    * @returns The driver for creating sessions.
    */
   export function createQldbDriver(
       ledgerName: string = LEDGER_NAME,
       serviceConfigurationOptions: ClientConfiguration = {}
   ): QldbDriver {
       const qldbDriver: QldbDriver = new QldbDriver(ledgerName, serviceConfigurationOptions);
       return qldbDriver;
   }
   
   export function getQldbDriver(): QldbDriver {
       return qldbDriver;
   }
   
   /**
    * Connect to a session for a given ledger using default settings.
    * @returns Promise which fulfills with void.
    */
   var main = async function(): Promise<void> {
       try {
           log("Listing table names...");
           const tableNames: string[] = await qldbDriver.getTableNames();
           tableNames.forEach((tableName: string): void => {
               log(tableName);
           });
       } catch (e) {
           error(`Unable to create session: ${e}`);
       } 
   }
   
   if (require.main === module) {
       main();
   }
   ```

------
**참고**  
원장에서 데이터 트랜잭션을 실행하려면 지정된 원장에 연결할 QLDB 드라이버 객체를 만들어야 합니다. 이는 [이전 단계](getting-started.nodejs.step-1.md)에서 원장을 생성할 때 사용한 `qldbClient` 객체와는 다른 클라이언트 객체입니다. 이전 클라이언트는 [Amazon QLDB API 참조](api-reference.md)에 나열된 관리 API 작업을 실행하는 데만 사용됩니다.

1. 트랜스파일된 프로그램을 실행하려면 다음 명령을 입력합니다.

   ```
   node dist/ConnectToLedger.js
   ```

`vehicle-registration` 원장에 테이블을 생성하려면 [3단계: 테이블, 인덱스 및 샘플 데이터 생성](getting-started.nodejs.step-3.md)로 진행하세요.