JMX can incur an overhead to an application so many libraries have an option to switch it on explicitly. In order to get a JMX view into ActiveMQ (JMS implementation) you must switch on JMX on the container and on the ActiveMQ library. To active JMX under Tomcat you can follow these instructions to Allow remote JMX management for Tomcat or Switch on Tomcat JMX under Eclipse. Once Tomcat is set up you can set up JMX on ActiveMQ. The Broker is the place inside the messaging system, where all the action is. It contains the queues (pipeline messaging) and topics (publisher-subscriber) along with flow control and related information. Under a Spring bean configuration this would be set up like this:

<amq:broker start="true" brokerName="localhost" useJmx="true">
<!-- other configuration options -->
</amq:broker>