Java Management Extensions (JMX)



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Java Management Extensions (JMX) is a framework that provides a standard way of exposing Java resources, for example, application servers, to a system management infrastructure. Using the JMX framework, a provider can implement functions, such as listing the configuration settings, and editing the settings. This framework also includes a notification layer that management applications can use to monitor events such as the startup of an application server.

The key features of the WAS V6 implementation of JMX include:


JMX architecture

The JMX architecture is structured into three layers:

Instrumentation layer Dictates how resources can be wrapped within special Java beans, called managed beans (MBeans).
Agent layer Consists of the MBean server and agents, which provide a management infrastructure. The services that are implemented include:

  • Monitoring
  • Event notification
  • Timers

Management layer Defines how external management applications can interact with the underlying layers in terms of protocols, APIs, and so on. This layer uses an implementation of the distributed services specification (JSR-077), which is not yet part of the J2EE specification.


JMX distributed administration

The following figure shows how the JMX architecture fits into the overall distributed administration topology of a Network Deployment environment:

Figure 2: WAS distributed administration of JMX

The key points of this distributed administration architecture include:


JMX Mbeans

WAS provides a number of MBeans, each of which has different functions and operations available. For example, an application server MBean can expose operations such as start and stop. An application MBean can expose operations such as install and uninstall. Some JMX usage scenarios that one can encounter include:

The following example illustrates how to obtain an MBean:


set am [$AdminControl queryNames type=ApplicationManager,process=server1,*]


am = AdminControl.queryNames('type=ApplicationManager,process=server1,*')

Each WAS runtime MBean can have attributes, operations, and notifications. The complete documentation for each MBean that is supplied with WAS is available in an HTML table that is installed in each copy of the WAS product. Under the main installation directory for the product, there is the web directory. Under the web directory there is another directory called mbeanDocs. In the mbeanDocs directory there are several HTML files; one HTML file for each MBean supplied with WAS. There is also an index.html file that ties all the individual MBean files together in a top-level navigation tree. Each MBean provides a summary of its attributes, operations, and notifications.


JMX benefits


See Also

Scripting objects


Related Tasks

Getting started with scripting
Starting the wsadmin scripting client




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