CODEWITHSUNDEEP
jbossjmsmessagingsubscriber
Rickard
Rickard

Reputation:

How to get the number of JMS messages in a Topic

How do I get the number of JMS messages waiting to be consumed by a specific JMS message subscriber? I use the Topic model (publish/subscribe) and not the Queue model.

I want my MDB (message driven bean) to be able to figure out this information about the topic it listens to. To be clear; I want my MDB to get the number of messages waiting to be consumed.

I can't find any information in either on Internet or the documentation :(

I use JBoss Messaging 1.4.4.

Upvotes: 4

Views: 4704

Answers (2)

Pascal Thivent
Pascal Thivent

Reputation: 570595

AFAIK, JMS does not specify anything to count the number of messages in a destination.

You need to use JMX for this. Check out the MBean attributes of the Topic MBean in the documentation and/or the java documentation of TopicMBean#getMessageCounters(). The depth attribute of MessageCounter should be what you're looking for. But, to be honest, I don't know what you're gonna do with this information and if this has a sense for a Topic. A message will stay in a Topic as long as it hasn't been delivered to all subscribers and each subscriber typically hasn't any knowledge of its peers. So how would one MDB interpret a count of messages?

Also note that I couldn't find this MBean in JBoss Messaging 2.0.0.alpha1's javadoc. I don't know if it has been deprecated (according to the code in 1.4, it wasn't) or if the documentation is not up to date (after all, it's the alpha1 javadoc and I couldn't find a link for beta4).

EDIT: As skaffman pointed out, JBoss Messaging has been rebranded as HornetQ. It looks like there have been some changes in the API but concepts still apply. The documentation is here.

Upvotes: 5

skaffman
skaffman

Reputation: 403581

You can't, not with the JMS API. The internal JBossMessaging API may expose that information, but you'll have to go looking through that documentation to find it.

Upvotes: 0

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