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* Moves eip-aggregator to Java 11 * Moves eip-message-channel to Java 11 * Moves eip-publish-subscribe to Java 11 * Moves eip-splitter to Java 11 * Moves eip-wire-tap to Java 11 * Moves event-aggregator to Java 11 * Moves event-asynchronous to Java 11 * Moves event-driven-architecture to Java 11 * Moves event-queue to Java 11 * Moves event-sourcing to Java 11 * Moves execute-around to Java 11 * Moves extension-objects to Java 11
layout, title, folder, permalink, categories, tags
| layout | title | folder | permalink | categories | tags | |||
|---|---|---|---|---|---|---|---|---|
| pattern | Event Aggregator | event-aggregator | /patterns/event-aggregator/ | Structural |
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Intent
A system with lots of objects can lead to complexities when a client wants to subscribe to events. The client has to find and register for each object individually, if each object has multiple events then each event requires a separate subscription. An Event Aggregator acts as a single source of events for many objects. It registers for all the events of the many objects allowing clients to register with just the aggregator.
Class diagram
Applicability
Use the Event Aggregator pattern when
- Event Aggregator is a good choice when you have lots of objects that are potential event sources. Rather than have the observer deal with registering with them all, you can centralize the registration logic to the Event Aggregator. As well as simplifying registration, a Event Aggregator also simplifies the memory management issues in using observers.