On 06/02/2011 03:29 AM, John D. Ament wrote:

Something I've been thinking about for a while now is the mapping APIs used by Seam JMS. Currently, you write an interface to define routes used by JMS events. This requires a bit of extra code that I'm not a big fan of. What I was thinking was put an extra annotation on either the injection point of the event or the observer method. The idea is that the annotation would include all of the destination configuration necessary. For example:

@Inject @JMS("jms/QueueOne","jms/QueueTwo","jms/QueueThree") Event<MyType> myTypeEvent;

@JMS("jms/MyTopic")
public void handleMessages(@Observes Long longsInTopic) {

....

}

The issues I see, since essentially I have to create an extra observer/firing pair to support each of these, is how to determine the observed type in the event. In general, any thoughts? Is it possible to determine the event's type in this case? If so, does the approach make sense?

- John
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I think that it's still a good idea to separate the routing rules from the event firing / observing. The need for extra code could be addressed by further simplification of annotation configuration e.g:

@Route(type=EGRESS, payloadType=String.class, qualifiers={}, destinationJndiName="jms/MyTopic", destinationType=Topic.class)

or

@Route(type=INGRESS, payloadType=Long.class, qualifiers={}, destinationJndiName="jms/MyQueue", destinationType=Queue.class)

In the second example, attribute names may be a bit confusing (the Queue is actually a source, not a destination) thus using a separate annotation for each routing type may be a better approach
@EgressRoute(payloadType=String.class, qualifiers={}, destinationJndiName="jms/MyTopic", destinationType=Topic.class)
@IngressRoute(payloadType=Long.class, qualifiers={}, sourceJndiName="jms/MyQueue", sourceType=Queue.class)

Each of these annotations would represent a single routing rule. These rules could be expressed like:
@Routes({
   @EgressRoute(...),
   @EgressRoute(...),
   @IngressRoute(...)
})

This IMHO makes it easier to define routing rules compared to the interface approach[1]

[1] http://docs.jboss.org/seam/3/jms/3.0.0.Beta2/reference/en-US/html/mapping-interfaces.html