Proxy MBeans

A proxy MBean is an object that represents a specific MBean instance and that makes it easier to access that MBean. A management application instantiates a proxy so that it has a simple handle on a registered MBean, instead of needing to access the MBean server.

The manager can access MBeans by invoking the methods of their proxy object. The proxy formulates the corresponding management request to the MBean server. The operations are those that are possible on an MBean:

• Getting or setting attributes

• Invoking operations

• Registering or unregistering for notifications

Because dynamic MBeans expose their management interface only at runtime, they cannot have a specific proxy MBean. Instead they have a generic proxy whose methods have an extra parameter to specify the attribute or operation name. Figure 2–1 shows management components interacting with both standard and dynamic MBeans through both standard and generic proxies. Notice that a generic proxy can also represent a standard MBean.

Figure 2–1 Binding Proxy MBeans to Local and Remote Servers

Figure 2–1 also shows that proxies can be instantiated either locally in the agent or remotely in the manager. Since the MBean server and the connector client have the same API, management requests to either of them are identical. This creates a symmetry so that the same management components can be instantiated either in the agent or in the manager application. This feature contributes to the scalability of Java dynamic management applications.

A standard proxy is generated from a standard MBean using the proxygen compiler, supplied with the Java DMK. The resulting class then needs to be loaded wherever the proxy will be instantiated. Generic proxies provide less of an abstraction but do not need to be generated. They are part of the Java DMK libraries and are thus always available.