A JMS-Queue-Factory-Bean --> Reuse a injected jms queue in different beans

Question

I'm using jms with jboss/wildfly (jee6).

A JMS Queue can easily be injected using:

@Resource(name="java:jboss/exported/jms/queue/queuename")
private Queue myQueue;

Now I'd like to implement a central Stateless Bean which gets all the queues injected and which provides a single String parameterized method to retrieve the Queue in a factory like way:

@Resource(name="java:jboss/exported/jms/queue/queuename1")
private Queue myQueue1;

@Resource(name="java:jboss/exported/jms/queue/queuename2")
private Queue myQueue2;

public Queue getQueueIWant(String identifier) {
  if("IdentifyingString".equals(identifier))
  { return myQueue1; }
  if...
}

Inside another Bean this "FactoryBean" gets injected:

@EJB
private MyQueueFactory queueFactory;

and can easily be used:

...
Queue queue = queueFactory.getQueueIWant("AIdentifier");
producer = session.createProducer(queue);
...

The retrieved Queue instance will be used to send messages to the queue (MessageProducer) and to retrieve them (MessageConsumer) in different places (Beans). I have tried this implementation and it seems to work.

My Question is does anyone see any Problems with this? Could this lead to instability? Should i use jndiLookup instead? Is there a better/easier way? Or is this nice and possible :-) ?

Thanks Philipp

Answer 1

In your code you have managed to centralize the resource declration/injection, but at your usage site you still need to address each queue individually. So not much has been gained compared with direct injection.

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It seems that you are trying to have something like an array of queues together with resource injection, but resource injection in that case does not really scale: Each new queue requires a deployment.

In your case I suggest using a manual JNDI lookup in an iteration. Then you can put the queues in an array/list for further processing. You could even pass the number of queues as a parameter into the method, and so the number of queues can be changed dynamically at run-time:

Pseudo-code (not tested, just for illustration):

InitialContext ic = new InitialContext();
Queue[] qs = new Queue[count];
for (int i = 0; i < count; i++) {
  String name = "queue/queuename" + i;
  qs[i] = (Queue) ic.lookup(name);
}

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If the queue name is based on a run-time argument (like an incoming JMS message) a JNDI lookup would be suitable, because static resource injection and dynamic naming conflicts somehow. Using a dynamic JNDI lookup scales, as a deployment to support additional queues is not required.