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11.3. Event Service

The Event Service provides a flexible framework for asynchronous interaction between distributed objects. The asynchronous method invocation facility provided by the Dynamic Invocation Interface is a very basic form of the services the Event Service provides. These kinds of asynchronous communications can be useful in situations where notification, rather than interaction, is needed. You may want your client to be notified when data in a dynamically updated database is modified, for example. The Event Service provides a framework for setting up these communications channels.

Agents engaged in event services are distinguished as event consumers or event suppliers. In both cases, the agents can engage either in push or pull event communications. These four cases are represented by the PushConsumer, PullConsumer, PushSupplier, and PullSupplier interfaces. Event communications take place over EventChannel objects, to which consumers and suppliers of events are connected.

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