Java Management Extensions

How Do Model MBeans Work?

Like all other MBean types, model MBeans must be created and registered with the MBean server, and, as with dynamic MBeans, the management interface of your resource is exposed through metadata classes. The similarities end there.

Every compliant JMX implementation must ship a class called RequiredModelMBean. This class is instantiated and registered with the MBean server, and it implements several interfaces (including DynamicMBean) that make the life of the instrumentation developer easier. But what is it that makes a model MBean tick? What makes a model MBean work and live up to its reputation (which we discussed in the previous section)? The rest of this section is devoted to answering those questions.

Model MBean Descriptors

The key difference between instrumenting a resource as a model MBean versus as a dynamic MBean is the Descriptor interface. A class implementing this interface describes certain properties of the MBean to the agent level of the JMX architecture, other MBeans, and management applications. Each descriptor contains one or more fields, which have corresponding Object values. Think of a field as a property of the MBean that gives some other party in the system (usually a management application) a little “nugget” of information about the MBean or one of its features (such as an attribute or operation). Of course, in order to exploit the full power of a descriptor, the management application must know about model MBeans. If the management ...