JMX monitors

In addition to providing monitoring data when requested, some MBeans also provide monitors.

The JMX Provider supports the ability for an agent to create JMX Monitors. A JMX Monitor is an MBean that the JMX agent creates on the JMX Server. It monitors the value of an attribute of another MBean and sends a notification when that value meets some criteria. Thresholds are defined that enable the Monitor to report on specific attribute values.

Not all application servers support the creation of monitors from a JMX client, which is true for current releases of WebSphere® Application Server. JMX Monitors and Take Action commands can be included in your agent by selecting Include JMX monitor attribute groups and take actions under Global JMX Options.

Any MBean that reports on an attribute of another MBean can be considered a monitor. In practice, JMX defines three concrete monitor classes, which are the types of monitors that are created. The following concrete monitor types are created:
  • String monitor – watches a string attribute, reports equality, or inequality of that string.
  • Gauge monitor – watches a variable numeric attribute, reports up or down movement beyond threshold values.
  • Counter monitor – watches an increasing numeric attribute, reports when it reaches a threshold value or increases by a certain amount.
The following attribute groups might be automatically added to the agent to collect or represent JMX Monitor notifications:
  • Registered Monitors

    This attribute group displays all of the JMX Monitors that are added by the user.

  • Counter Notifications

    This attribute group reports all notifications that are received from Counter Monitors.

  • Gauge Notifications

    This attribute group reports all notification received from Gauge Monitors.

  • String Notifications

    This attribute group reports all notifications that are received from String Monitors.