[jboss-dev-forums] [Design of Messaging on JBoss (Messaging/JBoss)] - Re: rolled back messages delivered twice.

[timfox]

Yes, this is what I have been going on about for the last couple of weeks.

The session must be enlisted in the JTA tx *before* delivery occurs from the messaging provider, otherwise, to the provider the delivery was non transacted, since it didn't know about the tx at the time it delivered the message to JCA. So when you rollback it won't know about the delivery.

This is what is covered in ML's tx book chapter 5 what I was talking about.

You don't any kind of special message listener to do this correctly. You just need to:

a) When the listener is first created and before it is added to the session, enlist the session for the first time. Then by the time onMessage is called you know the session is already enlisted,

b) in *your* onMessage (JBMMessageHandler:onMessage) call the delegate onMessage, then delist and commit, then.... before returning from your onMessage, enlist the session again so by the time the next onMessage is called it's already enlisted,

Note however, you shouldn't be using the tm.begin(), tm.commit() methods.  These require commit or rollback to be called on the same thread as beging, which won't necessary work since subsequent invocations of onMessage can be called on different threads.

You should therefore cache a reference to the JTA transaction object and call commit/ rollback directly on that since it does not require same thread to call it, and moreover JBM does not care about transaction-thread associations.:

JTA spec, section 3.3.3
anonymous wrote : 
  | 
  | The Transaction.commit and Transaction.rollback methods allow the target
  | object to be comitted or rolled back. The calling thread is not required to have the same
  | transaction associated with the thread.
  | 
  | 

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