Amazon GameLift and Game Client/Server Interactions

This topic describes the interactions between a client app, a game server, and the managed GameLift service. See also the Amazon GameLift–Game Server/Client Interactions diagram.

Setting Up a New Server Process

1. The GameLift service launches a new server process on an Amazon Elastic Compute Cloud (Amazon EC2) instance.

2. The server process, as part of the launch process, calls these server API actions:

   • InitSDK() to initialize the server SDK.

   • ProcessReady() to communicate readiness to accept a game session and specify connection port and location of game session log files.

   It then waits for a callback from the GameLift service.

3. The GameLift service changes the status of the EC2 instance to ACTIVE, with 0 game sessions and 0 players.

4. The GameLift service begins calling the onHealthCheck callback regularly while the server process is active. The server process must report either healthy or not healthy within one minute.

Creating a Game Session

1. The Client app calls the client API action CreateGameSession().

2. The GameLift service searches for an active server with 0 game sessions. When found, it does the following:

   • Creates a new GameSession object, using the port setting reported by the server process in ProcessReady(), and sets its status to ACTIVATING.

   • Responds to the client app request with the GameSession object.

   • Invokes the onStartGameSession callback on the server process, passing the GameSession object.

3. The server process runs the onStartGameSession callback function. When ready to accept player connections, the server process calls the server API action ActivateGameSession() and waits for player connections.

4. The GameLift service changes the GameSession status to ACTIVE.

Adding a Player to a Game Session

1. The Client app calls the client API action CreatePlayerSession() with a game session ID.

2. The GameLift service checks the game session status (must be ACTIVE), and looks for an open player slot in the game session. If a slot is available, it does the following:

   • Creates a new PlayerSession object and sets its status to RESERVED.

   • Responds to the client app request with the PlayerSession object.

3. The Client app connects directly to the server process with the player session ID.

4. The server process calls the Server API action AcceptPlayerSession() to validate the player session ID. If validated, the GameLift service passes the PlayerSession object to the server process. The server process either accepts or rejects the connection.

5. The GameLift service does one of the following:

   • If the connection is accepted, sets the PlayerSession status to ACTIVE.

   • If no response is received within 60 seconds of the client app's original CreatePlayerSession() call, changes the PlayerSession status to TIMEDOUT and reopens the player slot in the game session.

Removing a Player From a Game Session

1. The Client app disconnects from the server process.

2. The server process detects the lost connection and calls the server API action RemovePlayerSession().

3. The GameLift service changes the PlayerSession status to COMPLETED and reopens the player slot in the game session.

Shutting down a Game Session

Shutting down a game session

1. The server process calls the server API action TerminateGameSession().

2. The GameLift service does the following:

   • Changes the GameSession status to TERMINATED.

   • Uploads game session logs to Amazon Simple Storage Service (Amazon S3).

   • Updates fleet utilization to indicate the server is idle(0 game sessions, 0 players).

Terminating a Server Process

1. The server process does the following:

   • Runs code that gracefully shuts down the server process.

   • Calls the server API action ProcessEnding() to inform the GameLift service.

2. The GameLift service does the following:

   • Uploads game session logs (if any) to Amazon S3.

   • Changes the server process status to TERMINATED.

   • Recycles instance resources based on the fleet's runtime configuration.

Responding to a Shutdown Request

1. The GameLift service invokes the server process's onProcessTerminate callback. This call is used to shut down a server process that has reported unhealthy or not responded with health status for three consecutive minutes.

2. The server process runs the onProcessTerminate callback function, which triggers the server's termination process, ending with a call to ProcessEnding().

3. The GameLift service does the following, either in response to receiving the ProcessEnding() call or after five minutes:

   • Uploads game session logs (if any) to Amazon S3.

   • Changes the server process status to TERMINATED.

   • Recycles instance resources based on the fleet's runtime configuration.