The Java Management Extension (JMX) monitor collects availability and performance metrics of Java applications. Similar to SNMP and WMI monitors, various applications (such as Tomcat) expose relevant metrics through the JMX monitor. See JMX Configuration for App Servers.
Note: If you have a firewall, you might need to update your firewall rules since the return JMX connections from the Java application are made at randomly high TCP port numbers.