A Basic Application

Eventing-style interactions involve a component that acts as a source or producer of events which are dispatched to a channel. In turn, consumer components are configured to listen on a channel for events. Similar to reference injection, a source component is injected with a producer proxy using the Fabric3 @Producer annotation. This proxy is responsible for dispatching messages to a channel. A component subscribes to a channel using a consumer method.

The following is an example of a source component with a an injected producer:

import org.fabric3.api.annotation.Producer;

public class BuyComponent implements BuyService {

   @Producer
   private BuyChannel buyChannel;

   public void process() {
      BuyEvent event = ...
      buyChannel.publish(event);*
   }
}

The above example uses the default producer name "buyChannel". Alternatively, a name could be specified on the @Producer annotation. The next excerpt subscribes to receive BuyEvents:

import org.fabric3.api.annotation.Consumer;

public class BuyListener {

   @Consumer("buyChannel")
   public void onEvent(BuyEvent event) {
      ...
   }
}

Producers, consumers, and channels are configured in a composite:

<composite ...>

   <component name="BuyComponent">
      <implementation.java .../>
      <producer name="buyChannel" target="BuyChannel"/>
   </component>

   <component name="BuyListener">
      <implementation.java .../>
      <consumer name="buyChannel" source="BuyChannel"/>
   </component>

   <channel name="BuyChannel"/>

</composite>

In this example, the producer, consumer, and channel are configured in a single composite. In many applications, these may be defined in different composites. For example, a composite may only contain channel definitions, while others contain definitions for producers and consumers.