[jboss-user] [Messaging, JMS & JBossMQ] - Joining messages (queues)

[obfuscator]

Hi!

I have the following use case:

*Wait for a free resource
*When resource is free, wait for next job, then use resource to process job.

So, i need to wait until there is BOTH a resource and a job available. All resources are equal, so I can use any resource with any job. 

What's the best way of accomplishing this?

My current (flawed?) implementation is as follows:

I'm putting the resources in one queue as they become available, and then I have an MDB registered for that queue (P2P).

The job queue is a separate queue, and jobs are added to the queue as soon as a request arrives (might be days or months between jobs, then suddenly I could get a large amount at once).

When a resource is ready, the onMessage()-method of my MDB is called. 
In this method, I then create a MessageConsumer for the job-queue, and call receive() with infinite timeout. This seems to be a sub-optimal solution, since i'm blocking the MDB thread and Jboss AS seems to dislike my approach (refuses to shutdown while thread is blocked) ;)

I've also tried another solution, where I have a n second timeout on the receive method, and call ctx.setRollbackOnly() if no job is available when a resource is free. 

This makes JBoss assume that the operation failed non-intentionally and puts all my messages in the dead-letter-queue after 10 retries. I could increase the max amount of retries, but it feels like I'm going down the wrong road here... Is there a nicer way of joining messages?

I basically have free hands when it comes to this, so any suggestion is more than welcomed! 

Best regards

Alex

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