Listening for several input queues

Question

Hi!
My application receives messages from several queues. I also need to know for each message what queue is it from. That's why I had to define separate MessageListener's for each queue. So each queue has its instance of MyListener (see below). I synchronized the onMessage method on static Object, so only one message from all queues is processed in given moment:
MyListener implements MessageListener
static Object object;
onMessage (Message message)
synchronized (object)
//process
The problem is, that while processing current message, new messages (I suppose one per queue) are already taken from the queue and waiting to be processed. Thus if my application will shut down I will loose at least one message per queue. I'd like to hear your suggestions.
Thanks.

Answer 1

Rather than creating multiple listeners, you can write one listener with a case like structure:
public void onMessage(Message m) {
Queue queue = (Queue) m.getJMSDestination();
String name = queue.getName();
if (name.equals("q1")) {
// what the message listener for q1 would do ...
} else if (name.equals("q2")) {
// etc
You can then register this message listener for multiple queues. The motivation for doing this was a requirement that the execution of the message listeners had to be serialized. You can also achieve this by creating the queue receivers from the same session.
If there is no serialization requirement it's a matter of taste whether you prefer the combo listener above or multiple listeners. In this case you also can create the sessions from different connections to get concurrent message dispatch and possibly better performance.
- Bjarne.