2009/1/8 Davis Ford <[email protected]>:
> Hi, regarding the @Consumed annotation
>
> http://activemq.apache.org/camel/maven/camel-jpa/apidocs/org/apache/camel/component/jpa/Consumed.html
>
> I'm a bit curious how this works. If I have the following setup:
>
> NodeA <----> OracleDB <----> NodeB
>
> Where I have a JpaProducer on NodeA and a JpaConsumer on NodeB
>
> And I have something like
>
> @Entity
> public class MyEntity {
>
> etc..
>
> @Consumed
> public void consumed() {
> System.out.println("Message was consumed");
> }
> }
>
> I tried this out in a single JVM test that hits an oracle database and
> it works. I get a callback on the @Consumed method. But in a
> distributed environment -- how does this work? How would the producer
> on NodeA know that the consumer on NodeB got the Exchange?
The JVM that is processing an entity bean has the @Consumed method
invoked as a kinda lifecycle hook - as an alternative to the entity
bean just being deleted.
> Follow up question: The @Consumed annotation will come in really
> handy for me if I can get it to work the way I want. Here's what I am
> attempting to do:
>
> 1. Producer sends message
> 2. Consumer gets message
> 3. Consumer has to do some operation that may fail
> 3a. If it does fail I do not want the producer notified that the
> message was consumed
> 3b. If it does not fail, I want the producer notified so it can do
> some local cleanup
So either your producer could poll using a JPA query for entities
which are marked processed; or you could explicitly send a
notification message?
FWIW if the processing of the consumer fails, you might want to just
rollback the transaction and retry again later?
> Maybe the @Consumed is not what I want -- is there some way to insert
> a hook on the consumer side to control when the producer would get
> notified?
from("jpa:MyEntityBean").to("activemq:TheProducersQueue");
--
James
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