Introduction to Extend Event Handler
Overview
Extend Event Handler lets you run custom logic in response to AGS events. When something happens in the backend — like a match ending or a season completing — your app receives the event and takes action, without requiring a game client update.
An Extend Event Handler app is a gRPC service that receives AGS events through Kafka Connect and executes custom logic based on those events.
When an AGS service publishes an event to Kafka, a Kafka Connect sidecar bundled with your app consumes it and forwards it to your app's gRPC server, which invokes your custom logic.
Benefits
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Event-driven custom logic: React to backend events automatically. For example, grant entitlements at the end of a season or update player stats after a match — all without game client involvement.
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No game client updates required: Change your event handling logic at any time by updating and redeploying your app. Players don't need to download anything.
Considerations
Because each Event Handler replica includes a Kafka Connect sidecar, it carries more resource overhead than other Extend app types. Where possible, consolidate your event handling logic into a single app that handles multiple event types, rather than deploying separate apps per event. This reduces the number of Kafka Connect instances running in your environment.
API Events
You can find all available events in the API Events section.
Event Descriptor
You can find a Protocol Buffers (Protobuf) file that serves as an event descriptor in the AccelByte API proto GitHub repo. Each event on the API Events page also links directly to its proto file.
REST API support
Event Handler apps can also expose REST API endpoints using the same gRPC Gateway stack as Extend Service Extension. This allows a single app to both react to AGS events and serve custom RESTful endpoints. See REST API support for details.