ActiveMQ get number of consumers listening to a topic from java

Question

I would like to be able to get the number of consumers listening to a topic from java for an embedded ActiveMQ (5.4.2) broker in the same JVM. Is JMX really the only option here? JMX seems like a bad option since it may be optionally disabled. This post shows how to use JMX to get a list of connections: ActiveMQ: Get list of connections through JMX?

I would prefer a non-JMX based solution though due to it perhaps being disabled. I guess JMX would be ok if it was still usable from java when disabled. I am just familiar with enabling/disabling it for use with jconsole.

Am I missing something in the API?

Bodyguard

Answer 1

you can use Advisory Messages to get the number of consumers of queues/topics (amongst other things) without using JMX (see ActiveMQ.Advisory.Consumer.Topic, etc)...

Force

Answer 2

I think that the consumer count in the statistics plugin should give you what you want. And I'm fairly sure that the statistics plugin can be enabled in an embedded broker.

http://activemq.apache.org/statisticsplugin.html

Condescendence

I like this (+1) but am going to go with boday for the check since that appears to be a simpler technique for what I am after, i.e. does not require a plugin. – Bodyguard

Answer 3

I do it simply by fireing this GET: http://localhost:8161/admin/xml/queues.jsp

It returns a list of all queues with registered consumers in XML:

<?xml version="1.0" encoding="UTF-8"?>
<queues>
    <queue name="sauer_test2">
        <stats size="0" consumerCount="0" enqueueCount="0" dequeueCount="0"/>
        <feed>
            <atom>queueBrowse/sauer_test2?view=rss&amp;amp;feedType=atom_1.0</atom>
            <rss>queueBrowse/sauer_test2?view=rss&amp;amp;feedType=rss_2.0</rss>
        </feed>
    </queue>
    <queue name="sauer_test1">
        <stats size="0" consumerCount="1" enqueueCount="1" dequeueCount="1"/>
        <feed>
            <atom>queueBrowse/sauer_test1?view=rss&amp;amp;feedType=atom_1.0</atom>
            <rss>queueBrowse/sauer_test1?view=rss&amp;amp;feedType=rss_2.0</rss>
        </feed>
    </queue>
</queues>

You can see the "consumerCount" attribute and react, accordingly. There is also a get method for getting all consumer-details of a given queue: http://localhost:8161/admin/queueConsumers.jsp?JMSDestination=sauer_test1.

Curlew

Answer 4

In case of embedded ActiveMQ you may use BrokerService, to get consumers count on topic. Code is in Scala, but there shouldn't be much difference in Java.

            import org.apache.activemq.broker.{BrokerService, TransportConnector}

            val brokerService = new BrokerService()
            brokerService.setBrokerName("localhost")
            brokerService.setUseJmx(false)
            val transportConnector: TransportConnector = brokerServiceSetup.addConnector(s"tcp://localhost:61616")
            brokerService.start()
            brokerService.getDestination(new ActiveMQTopic(topicName))
            topic.getConsumers

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