JDK5 comes bundled with a JMX v1.2 implementation and a set of monitoring MBeans called platform MBeans or MXBeans (do not confuse those with JBoss XMBeans :) Those MXBeans can be accessed through the platform MBeanServer, which is more or less a normal MBeanServer but it is instantiated by the JVM itself, upon first access.

A nice example of underlying usage of a platform MBean can be seen in (soon-to-be-released) JBoss v3.2.8/4.0.2. By utilizing the ThreadMXBean we can output to the jmx-console a full stack trace of all running threads in JBoss, without having to revert to the command line (as it was done previously). Of course, this only works when running under a JDK5+ runtime.

Check out our wiki for more info.

dimitris@jboss