# Player sessions and matchmaking customizations
<a name="customize-player-sessions-matchmaking"></a>

Player session and matchmaking customizations give you the opportunity to develop sophisticated player management workflows, including a nuanced matchmaking system that helps you deliver balanced, engaging multiplayer experiences.

# Generate player IDs
<a name="player-sessions-player-identifiers"></a>

Amazon GameLift Servers uses a player session to represent a player connected to a game session. Amazon GameLift Servers creates a player session each time a player connects to a game session using a game client integrated with Amazon GameLift Servers. When a player leaves a game, the player session ends. Amazon GameLift Servers doesn't reuse player sessions.

**Important**  
When using FlexMatch matchmaking, if you create a new matchmaking request that contains a player ID that is already included in an existing active matchmaking request, the existing request is automatically cancelled. However, a `MatchmakingCancelled` event is not sent for the cancelled request. To monitor the status of existing matchmaking requests, use [DescribeMatchmaking](https://docs.aws.amazon.com/gamelift/latest/apireference/API_DescribeMatchmaking.html) to poll the request status at infrequent intervals (30-60 seconds). The cancelled request will show a status of `CANCELLED` with the reason `Cancelled due to duplicate player`.

The following code example randomly generates unique player IDs:

```
bool includeBrackets = false;
bool includeDashes = true;
string playerId = AZ::Uuid::CreateRandom().ToString<string>(includeBrackets, includeDashes);
```

For more information about player sessions, see [Game and player sessions in the Amazon GameLift Servers console](gamelift-console-game-player-sessions-metrics.md).

# Add FlexMatch matchmaking to Amazon GameLift Servers
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Use Amazon GameLift Servers FlexMatch to add player matchmaking functionality to your Amazon GameLift Servers hosted games. You can use FlexMatch with either custom game servers or Amazon GameLift Servers Realtime. 

FlexMatch pairs the matchmaking service with a customizable rules engine. You design how to match players together based on player attributes and game modes that make sense for your game. FlexMatch manages the nuts and bolts of evaluating players who are looking for a game, forming matches with one or more teams, and starting game sessions to host the matches. 

To use the full FlexMatch service, you must have your hosting resources set up with queues. Amazon GameLift Servers uses queues to locate the best possible hosting locations for games across multiple regions and computing types. In particular, Amazon GameLift Servers queues can use latency data, when provided by game clients, to place game sessions so that players experience the lowest possible latency when playing.

For more information on FlexMatch including detailed help with integrating matchmaking into your games, see these [Amazon GameLift Servers FlexMatch Developer Guide](https://docs.aws.amazon.com/gamelift/latest/flexmatchguide/) topics:
+ [How Amazon GameLift Servers FlexMatch works](https://docs.aws.amazon.com/gamelift/latest/flexmatchguide/match-intro.html)
+ [FlexMatch integration steps](https://docs.aws.amazon.com/gamelift/latest/flexmatchguide/match-tasks.html)