How can I handle multiple messages concurrently from a JMS topic (not queue) with java and spring 3.0?

Question

Note that I\'d like multiple message listeners to handle successive messages from the topic concurrently. In addition I\'d like each message listener to operate transaction

Answer 1

Here's a possibility:

1) create only one DMLC configured with the bean and method to handle the incoming message. Set its concurrency to 1.

2) Configure a task executor with its #threads equal to the concurrency you desire. Create an object pool for objects which are actually supposed to process a message. Give a reference of task executor and object pool to the bean you configured in #1. Object pool is useful if the actual message processing bean is not thread-safe.

3) For an incoming message, the bean in DMLC creates a custom Runnable, points it to the message and the object pool, and gives it to task executor.

4) The run method of Runnable gets a bean from the object pool and calls its 'process' method with the message given.

#4 can be managed with a proxy and the object pool to make it easier.

I haven't tried this solution yet, but it seems to fit the bill. Note that this solution is not as robust as EJB MDB. Spring e.g. will not discard an object from the pool if it throws a RuntimeException.