A diagnostic system module is a configurable software component that monitors aspects of running server instances. You can configure diagnostic system modules to monitor single, stand-alone server instances, selected server instances in a cluster, or all the server instances in a cluster.
A diagnostic module can be targeted to one or more server instances and/or clusters at a time. In addition, multiple modules can be targeted to a given server instance and active simultaneously. Diagnostic modules are not available for monitoring domains.
You can also dynamically activate or deactive a diagnostic system module without restarting the targeted server or cluster instance or making a change to the domain configuration.
Once you have created the diagnostic system module, you can configure metrics, policies and actions, and instrumentation (diagnostic monitors).
Note that the WebLogic Diagnostics Framework (WLDF) also provides a set of built-in system diagnostic modules, which are preconfigured to monitor the main components of a server instance, such as the JVM, the WebLogic Server run time, and key components and services. Enabling a built-in module provides a simple and easy-to-use alternative to configuring a diagnostic system module from scratch. For more information, see Activate a built-in diagnostic system module.