2.1.3 Model MBeans

A model MBean is a generic, configurable, dynamic MBean that you can use to instrument a resource at runtime. A model MBean is an MBean template. The caller tells the model MBean what management interface to expose. The caller also determines how attributes and operations are implemented, by designating a target object on which attribute access and operation invocation are actually performed.

The model MBean implementation class is mandated by the JMX specification and therefore is always available for instantiation in an agent. Management applications can use model MBeans to instrument resources on the fly.

To instrument a resource and expose it dynamically, you need to:

• Instantiate the javax.management.modelmbean.RequiredModelMBean class in a JMX agent

• Set the model MBean's management interface

• Designate the target object that implements the management interface

• Register the model MBean in the MBean server

The management interface of a model MBean is dynamic, and it is also exposed dynamically. The application that configures a model MBean can modify its management interface at any time. The application can also change its implementation by designating a new target object.

Management applications access all types of MBeans in the same manner, and most applications are not aware of the various MBean types. However, if a manager understands model MBeans, it can obtain additional management information about the managed resource. This information includes behavioral and runtime metadata that is specific to model MBeans.