# Server SDK (Unreal) for Amazon GameLift Servers -- Actions
<a name="integration-server-sdk-unreal-ref-actions"></a>

Use the server SDK for Unreal to integrate your multiplayer game for hosting with Amazon GameLift Servers. For guidance about the integration process, see [Add Amazon GameLift Servers to your game server with the server SDK](gamelift-sdk-server-api.md).

**Note**  
This reference is for an earlier version of the server SDK for Amazon GameLift Servers. For the latest version, see [C\+\+ (Unreal) server SDK 5.x for Amazon GameLift Servers -- Actions](integration-server-sdk5-unreal-actions.md).

This API is defined in `GameLiftServerSDK.h` and `GameLiftServerSDKModels.h`.

To set up the Unreal Engine plugin and see code examples [Integrate Amazon GameLift Servers into an Unreal Engine project](integration-engines-setup-unreal.md).

[Server SDK (Unreal) for Amazon GameLift Servers -- Data types](integration-server-sdk-unreal-ref-datatypes.md)

**Topics**
+ [Server SDK (Unreal) for Amazon GameLift Servers -- Data types](integration-server-sdk-unreal-ref-datatypes.md)
+ [AcceptPlayerSession()](#integration-server-sdk-unreal-ref-acceptplayersession)
+ [ActivateGameSession()](#integration-server-sdk-unreal-ref-activategamesession)
+ [DescribePlayerSessions()](#integration-server-sdk-unreal-ref-describeplayersessions)
+ [GetGameSessionId()](#integration-server-sdk-unreal-ref-getgamesessionid)
+ [GetInstanceCertificate()](#integration-server-sdk-unreal-ref-getinstancecertificate)
+ [GetSdkVersion()](#integration-server-sdk-unreal-ref-getsdk)
+ [InitSDK()](#integration-server-sdk-unreal-ref-initsdk)
+ [ProcessEnding()](#integration-server-sdk-unreal-ref-processending)
+ [ProcessReady()](#integration-server-sdk-unreal-ref-processready)
+ [RemovePlayerSession()](#integration-server-sdk-unreal-ref-removeplayersession)
+ [StartMatchBackfill()](#integration-server-sdk-unreal-ref-startmatchbackfill)
+ [StopMatchBackfill()](#integration-server-sdk-unreal-ref-stopmatchbackfill)
+ [TerminateGameSession()](#integration-server-sdk-unreal-ref-terminategamesession)
+ [UpdatePlayerSessionCreationPolicy()](#integration-server-sdk-unreal-ref-updateplayersessioncreationpolicy)

## AcceptPlayerSession()
<a name="integration-server-sdk-unreal-ref-acceptplayersession"></a>

Notifies the Amazon GameLift Servers service that a player with the specified player session ID has connected to the server process and needs validation. Amazon GameLift Servers verifies that the player session ID is valid—that is, that the player ID has reserved a player slot in the game session. Once validated, Amazon GameLift Servers changes the status of the player slot from RESERVED to ACTIVE. 

### Syntax
<a name="integration-server-sdk-unreal-ref-acceptplayersession-syntax"></a>

```
FGameLiftGenericOutcome AcceptPlayerSession(const FString& playerSessionId)
```

### Parameters
<a name="integration-server-sdk-unreal-ref-acceptplayersession-parameter"></a>

**playerSessionId**  
Unique ID issued by the Amazon GameLift Servers service in response to a call to the AWS SDK Amazon GameLift Servers API action [CreatePlayerSession](https://docs.aws.amazon.com/gamelift/latest/apireference/API_CreatePlayerSession.html). The game client references this ID when connecting to the server process.  
Type: FString  
Required: Yes

### Return value
<a name="integration-server-sdk-unreal-ref-acceptplayersession-return"></a>

Returns a generic outcome consisting of success or failure with an error message. 

## ActivateGameSession()
<a name="integration-server-sdk-unreal-ref-activategamesession"></a>

Notifies the Amazon GameLift Servers service that the server process has activated a game session and is now ready to receive player connections. This action should be called as part of the `onStartGameSession()` callback function, after all game session initialization has been completed.

### Syntax
<a name="integration-server-sdk-unreal-ref-activategamesession-syntax"></a>

```
FGameLiftGenericOutcome ActivateGameSession()
```

### Parameters
<a name="integration-server-sdk-unreal-ref-activategamesession-parameter"></a>

This action has no parameters.

### Return value
<a name="integration-server-sdk-unreal-ref-activategamesession-return"></a>

Returns a generic outcome consisting of success or failure with an error message.

## DescribePlayerSessions()
<a name="integration-server-sdk-unreal-ref-describeplayersessions"></a>

Retrieves player session data, including settings, session metadata, and player data. Use this action to get information for a single player session, for all player sessions in a game session, or for all player sessions associated with a single player ID.

### Syntax
<a name="integration-server-sdk-unreal-ref-describeplayersessions-syntax"></a>

```
FGameLiftDescribePlayerSessionsOutcome DescribePlayerSessions(const FGameLiftDescribePlayerSessionsRequest &describePlayerSessionsRequest)
```

### Parameters
<a name="integration-server-sdk-unreal-ref-describeplayersessions-parameter"></a>

**describePlayerSessionsRequest**  
A [FDescribePlayerSessionsRequest](integration-server-sdk-unreal-ref-datatypes.md#integration-server-sdk-unreal-ref-dataypes-playersessions) object describing which player sessions to retrieve.  
Required: Yes

### Return value
<a name="integration-server-sdk-unreal-ref-describeplayersessions-return"></a>

If successful, returns a [FDescribePlayerSessionsRequest](integration-server-sdk-unreal-ref-datatypes.md#integration-server-sdk-unreal-ref-dataypes-playersessions) object containing a set of player session objects that fit the request parameters. Player session objects have a structure identical to the AWS SDK Amazon GameLift Servers API [PlayerSession](https://docs.aws.amazon.com/gamelift/latest/apireference/API_PlayerSession.html) data type.

## GetGameSessionId()
<a name="integration-server-sdk-unreal-ref-getgamesessionid"></a>

Retrieves the ID of the game session currently being hosted by the server process, if the server process is active. 

### Syntax
<a name="integration-server-sdk-unreal-ref-getgamesessionid-syntax"></a>

```
FGameLiftStringOutcome GetGameSessionId()
```

### Parameters
<a name="integration-server-sdk-unreal-ref-getgamesessionid-parameter"></a>

This action has no parameters.

### Return value
<a name="integration-server-sdk-unreal-ref-getgamesessionid-return"></a>

If successful, returns the game session ID as an `FGameLiftStringOutcome` object. If not successful, returns an error message.

## GetInstanceCertificate()
<a name="integration-server-sdk-unreal-ref-getinstancecertificate"></a>

Retrieves the file location of a pem-encoded TLS certificate that is associated with the fleet and its instances. AWS Certificate Manager generates this certificate when you create a new fleet with the certificate configuration set to GENERATED. Use this certificate to establish a secure connection with a game client and to encrypt client/server communication. 

### Syntax
<a name="integration-server-sdk-unreal-ref-getinstancecertificate-syntax"></a>

```
FGameLiftGetInstanceCertificateOutcome GetInstanceCertificate()
```

### Parameters
<a name="integration-server-sdk-unreal-ref-getinstancecertificate-parameter"></a>

This action has no parameters.

### Return value
<a name="integration-server-sdk-unreal-ref-getinstancecertificate-return"></a>

If successful, returns a `GetInstanceCertificateOutcome` object containing the location of the fleet's TLS certificate file and certificate chain, which are stored on the instance. A root certificate file, extracted from the certificate chain, is also stored on the instance. If not successful, returns an error message. 

For more information about the certificate and certificate chain data, see [GetCertificate Response Elements](https://docs.aws.amazon.com/acm/latest/APIReference/API_GetCertificate.html#API_GetCertificate_ResponseElements) in the AWS Certificate Manager API Reference.

## GetSdkVersion()
<a name="integration-server-sdk-unreal-ref-getsdk"></a>

Returns the current version number of the SDK built into the server process.

### Syntax
<a name="integration-server-sdk-unreal-ref-getsdk-syntax"></a>

```
FGameLiftStringOutcome GetSdkVersion();
```

### Parameters
<a name="integration-server-sdk-unreal-ref-getsdk-parameter"></a>

This action has no parameters.

### Return value
<a name="integration-server-sdk-unreal-ref-getsdk-return"></a>

If successful, returns the current SDK version as an `FGameLiftStringOutcome` object. The returned string includes the version number only (ex. "3.1.5"). If not successful, returns an error message.

### Example
<a name="integration-server-sdk-unreal-ref-getsdk-example"></a>

```
Aws::GameLift::AwsStringOutcome SdkVersionOutcome = 
    Aws::GameLift::Server::GetSdkVersion();
```

## InitSDK()
<a name="integration-server-sdk-unreal-ref-initsdk"></a>

Initializes the Amazon GameLift Servers SDK. This method should be called on launch, before any other Amazon GameLift Servers-related initialization occurs.

### Syntax
<a name="integration-server-sdk-unreal-ref-initsdk-syntax"></a>

```
FGameLiftGenericOutcome InitSDK()
```

### Parameters
<a name="integration-server-sdk-unreal-ref-initsdk-parameter"></a>

This action has no parameters.

### Return value
<a name="integration-server-sdk-unreal-ref-initsdk-return"></a>

Returns a generic outcome consisting of success or failure with an error message.

## ProcessEnding()
<a name="integration-server-sdk-unreal-ref-processending"></a>

Notifies the Amazon GameLift Servers service that the server process is shutting down. This method should be called after all other cleanup tasks, including shutting down all active game sessions. This method should exit with an exit code of 0; a non-zero exit code results in an event message that the process did not exit cleanly.

### Syntax
<a name="integration-server-sdk-unreal-ref-processending-syntax"></a>

```
FGameLiftGenericOutcome ProcessEnding()
```

### Parameters
<a name="integration-server-sdk-unreal-ref-processending-parameter"></a>

This action has no parameters.

### Return value
<a name="integration-server-sdk-unreal-ref-processending-return"></a>

Returns a generic outcome consisting of success or failure with an error message.

## ProcessReady()
<a name="integration-server-sdk-unreal-ref-processready"></a>

Notifies the Amazon GameLift Servers service that the server process is ready to host game sessions. Call this method after successfully invoking [InitSDK()](#integration-server-sdk-unreal-ref-initsdk) and completing setup tasks that are required before the server process can host a game session. This method should be called only once per process.

### Syntax
<a name="integration-server-sdk-unreal-ref-processready-syntax"></a>

```
FGameLiftGenericOutcome ProcessReady(FProcessParameters &processParameters)
```

### Parameters
<a name="integration-server-sdk-unreal-ref-processready-parameter"></a>

**FProcessParameters**  
A [FProcessParameters](integration-server-sdk-unreal-ref-datatypes.md#integration-server-sdk-unreal-ref-dataypes-process) object communicating the following information about the server process:  
+ Names of callback methods, implemented in the game server code, that the Amazon GameLift Servers service invokes to communicate with the server process.
+ Port number that the server process is listening on.
+ Path to any game session-specific files that you want Amazon GameLift Servers to capture and store.
Required: Yes

### Return value
<a name="integration-server-sdk-unreal-ref-processready-return"></a>

Returns a generic outcome consisting of success or failure with an error message.

### Example
<a name="integration-server-sdk-unreal-ref-processready-example"></a>

See the sample code in [Using the Unreal Engine Plugin](integration-engines-setup-unreal.md#integration-engines-setup-unreal-code).

## RemovePlayerSession()
<a name="integration-server-sdk-unreal-ref-removeplayersession"></a>

Notifies the Amazon GameLift Servers service that a player with the specified player session ID has disconnected from the server process. In response, Amazon GameLift Servers changes the player slot to available, which allows it to be assigned to a new player. 

### Syntax
<a name="integration-server-sdk-unreal-ref-removeplayersession-syntax"></a>

```
FGameLiftGenericOutcome RemovePlayerSession(const FString& playerSessionId)
```

### Parameters
<a name="integration-server-sdk-unreal-ref-removeplayersession-parameter"></a>

**playerSessionId**  
Unique ID issued by the Amazon GameLift Servers service in response to a call to the AWS SDK Amazon GameLift Servers API action [CreatePlayerSession](https://docs.aws.amazon.com/gamelift/latest/apireference/API_CreatePlayerSession.html). The game client references this ID when connecting to the server process.  
Type: FString  
Required: Yes

### Return value
<a name="integration-server-sdk-unreal-ref-removeplayersession-return"></a>

Returns a generic outcome consisting of success or failure with an error message.

## StartMatchBackfill()
<a name="integration-server-sdk-unreal-ref-startmatchbackfill"></a>

Sends a request to find new players for open slots in a game session created with FlexMatch. See also the AWS SDK action [StartMatchBackfill()](https://docs.aws.amazon.com/gamelift/latest/apireference/API_StartMatchBackfill.html). With this action, match backfill requests can be initiated by a game server process that is hosting the game session. Learn more about the [FlexMatch backfill feature](https://docs.aws.amazon.com/gamelift/latest/flexmatchguide/match-backfill.html).

This action is asynchronous. If new players are successfully matched, the Amazon GameLift Servers service delivers updated matchmaker data using the callback function `OnUpdateGameSession()`.

A server process can have only one active match backfill request at a time. To send a new request, first call [StopMatchBackfill()](#integration-server-sdk-unreal-ref-stopmatchbackfill) to cancel the original request.

### Syntax
<a name="integration-server-sdk-unreal-ref-startmatchbackfill-syntax"></a>

```
FGameLiftStringOutcome StartMatchBackfill (FStartMatchBackfillRequest &startBackfillRequest);
```

### Parameters
<a name="integration-server-sdk-unreal-ref-startmatchbackfill-parameter"></a>

**FStartMatchBackfillRequest**  
A [FStartMatchBackfillRequest](integration-server-sdk-unreal-ref-datatypes.md#integration-server-sdk-unreal-ref-dataypes-startmatchbackfillrequest) object that communicates the following information:  
+ A ticket ID to assign to the backfill request. This information is optional; if no ID is provided, Amazon GameLift Servers will autogenerate one.
+ The matchmaker to send the request to. The full configuration ARN is required. This value can be acquired from the game session's matchmaker data.
+ The ID of the game session that is being backfilled.
+ Available matchmaking data for the game session's current players.
Required: Yes

### Return value
<a name="integration-server-sdk-unreal-ref-startmatchbackfill-return"></a>

If successful, returns the match backfill ticket as a `FGameLiftStringOutcome` object. If not successful, returns an error message. Ticket status can be tracked using the AWS SDK action [DescribeMatchmaking()](https://docs.aws.amazon.com/gamelift/latest/apireference/API_DescribeMatchmaking.html).

## StopMatchBackfill()
<a name="integration-server-sdk-unreal-ref-stopmatchbackfill"></a>

Cancels an active match backfill request that was created with [StartMatchBackfill()](#integration-server-sdk-unreal-ref-startmatchbackfill). See also the AWS SDK action [StopMatchmaking()](https://docs.aws.amazon.com/gamelift/latest/apireference/API_StopMatchmaking.html). Learn more about the [FlexMatch backfill feature](https://docs.aws.amazon.com/gamelift/latest/flexmatchguide/match-backfill.html).

### Syntax
<a name="integration-server-sdk-unreal-ref-stopmatchbackfill-syntax"></a>

```
FGameLiftGenericOutcome StopMatchBackfill (FStopMatchBackfillRequest &stopBackfillRequest);
```

### Parameters
<a name="integration-server-sdk-unreal-ref-stopmatchbackfill-parameter"></a>

**StopMatchBackfillRequest**  
A [FStopMatchBackfillRequest](integration-server-sdk-unreal-ref-datatypes.md#integration-server-sdk-unreal-ref-dataypes-stopmatchbackfillrequest) object identifying the matchmaking ticket to cancel:   
+ ticket ID assigned to the backfill request being canceled
+ matchmaker the backfill request was sent to
+ game session associated with the backfill request
Required: Yes

### Return value
<a name="integration-server-sdk-unreal-ref-stopmatchbackfill-return"></a>

Returns a generic outcome consisting of success or failure with an error message.

## TerminateGameSession()
<a name="integration-server-sdk-unreal-ref-terminategamesession"></a>

**This method is deprecated with version 4.0.1. Instead, the server process should call [ProcessEnding()](#integration-server-sdk-unreal-ref-processending) after a game session has ended.**

Notifies the Amazon GameLift Servers service that the server process has ended the current game session. This action is called when the server process will remain active and ready to host a new game session. It should be called only after your game session termination procedure is complete, because it signals to Amazon GameLift Servers that the server process is immediately available to host a new game session. 

This action is not called if the server process will be shut down after the game session stops. Instead, call [ProcessEnding()](#integration-server-sdk-unreal-ref-processending) to signal that both the game session and the server process are ending. 

### Syntax
<a name="integration-server-sdk-unreal-ref-terminategamesession-syntax"></a>

```
FGameLiftGenericOutcome TerminateGameSession()
```

### Parameters
<a name="integration-server-sdk-unreal-ref-terminategamesession-parameter"></a>

This action has no parameters.

### Return value
<a name="integration-server-sdk-unreal-ref-terminategamesession-return"></a>

Returns a generic outcome consisting of success or failure with an error message.

## UpdatePlayerSessionCreationPolicy()
<a name="integration-server-sdk-unreal-ref-updateplayersessioncreationpolicy"></a>

Updates the current game session's ability to accept new player sessions. A game session can be set to either accept or deny all new player sessions. (See also the [https://docs.aws.amazon.com/gamelift/latest/apireference/API_UpdateGameSession.html](https://docs.aws.amazon.com/gamelift/latest/apireference/API_UpdateGameSession.html) action in the *Amazon GameLift Servers Service API Reference*).

### Syntax
<a name="integration-server-sdk-unreal-ref-updateplayersessioncreationpolicy-syntax"></a>

```
FGameLiftGenericOutcome UpdatePlayerSessionCreationPolicy(EPlayerSessionCreationPolicy policy)
```

### Parameters
<a name="integration-server-sdk-unreal-ref-updateplayersessioncreationpolicy-parameter"></a>

**Policy**  
Value indicating whether the game session accepts new players.   
Type: `EPlayerSessionCreationPolicy` enum. Valid values include:  
+ **ACCEPT\_ALL** – Accept all new player sessions.
+ **DENY\_ALL** – Deny all new player sessions.
Required: Yes

### Return value
<a name="integration-server-sdk-unreal-ref-updateplayersessioncreationpolicy-return"></a>

Returns a generic outcome consisting of success or failure with an error message.