Java Implementation Model for Event Processing (TUSCANY) edited by Mike Edwards
Page:
http://cwiki.apache.org/confluence/display/TUSCANY/Java+Implementation+Model+for+Event+Processing
Changes:
http://cwiki.apache.org/confluence/pages/diffpagesbyversion.action?pageId=99635&originalVersion=7&revisedVersion=8
Content:
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This page describes the Java Implementation for Event Processing.
The Java Implementation for Event Processing is an extension of the standard
SCA Java Implementation model. All the standard SCA Java implementation
features continue to be available to Java implementations. The following
features are added:
* Ability to define one or more methods of the implementation class to be
*{_}consumer methods{_}*, consuming one or more *{_}event types{_}*
* Ability to define a field or setter method of the implementation class as an
event *{_}producer{_}*, with one or more business methods producing one or more
*{_}event types _*
* Ability to define *{_}event types{_}* as Java POJO classes
h2. Event Types
Event types are defined through Java classes which are annotated with a
@EventType annotation. The @EventType annotation has a single parameter
which is the *{_}name{_}* of the event type.
{code}
@EventType(ExampleEvent)
public class ExampleEvent {
public String eventData;
} // end class ExampleEvent
{code}
h2. Event Consumer methods
Each method of the implementation that is a consumer for events is annotated
with a @Consumer annotation. Each method must have a *{_}void{_}* return
type and a single parameter that is either a specific event type or a
superclass of one or more event types, including java.lang.Object, which is
treated as the supertype of all event types.
{code}
public class ConsumerrExample {
private ExampleProducer eventProducer;
@Consumer(ExampleConsumer)
public void someBusinessMethod() {
theEvent = new ExampleEvent();
theEvent.eventData = "Some Data";
eventProducer.produceExampleEvent( theEvent );
} // end method someBusinessMethod
} // end class
{code}
h2. Event Producers
Event Producers are identified as a Field or as a Setter method annotated with
a @Producer annotation
It is required that the Field or Setter method is typed by a Java
interface. The Java interface must have one or more methods, each of
which has a *{_}void{_}* return type and a single parameter that is either a
specific event type or a superclass of one or more event types, including
java.lang.Object, which is treated as the supertype of all event types.
{code}
@Remotable
public interface ExampleProducer {
void produceExampleEvent( ExampleEvent theEvent);
} // end interface ExampleProducer
@EventType(ExampleEvent)
public class ExampleEvent {
public String eventData;
} // end class ExampleEvent
public class ProducerExample {
private ExampleProducer eventProducer;
@Producer(ExampleEvent)
public void setEventProducer( ExampleProducer theProducer ) {
eventProducer = theProducer;
return;
} // end method setEventProducer
public void someBusinessMethod() {
theEvent = new ExampleEvent();
theEvent.eventData = "Some Data";
eventProducer.produceExampleEvent( theEvent );
} // end method someBusinessMethod
} // end class
{code}
h2. Example Java Implementation with Consumer and Producer
h3.
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