javax.management.modelmbean package

Provides the definition of the ModelMBean classes. A Model MBean is an MBean that acts as a bridge between the management interface and the underlying managed resource. Both the management interface and the managed resource are specified as Java objects. The same Model MBean implementation can be reused many times with different management interfaces and managed resources, and it can provide common functionality such as persistence and caching.

A Model MBean implements the {@link javax.management.modelmbean.ModelMBean ModelMBean} interface. It is a {@link javax.management.DynamicMBean DynamicMBean} whose {@link javax.management.DynamicMBean#getMBeanInfo() getMBeanInfo} method returns an object implementing {@link javax.management.modelmbean.ModelMBeanInfo ModelMBeanInfo}.

Every MBean has an {@link javax.management.MBeanInfo MBeanInfo} with information about the MBean itself, and its attributes, operations, constructors, and notifications. A Model MBean augments this `MBeanInfo` with {@link javax.management.Descriptor Descriptor}s that encode additional information in the form of (key,value) pairs. Usually, `Descriptor`s are instances of {@link javax.management.modelmbean.DescriptorSupport DescriptorSupport}.

The class {@link javax.management.modelmbean.RequiredModelMBean RequiredModelMBean} provides a standard Model MBean implementation.

The following example shows a Model MBean being used to make the `get` method of a `HashMap` available for management through an MBean server. No other methods are available through the MBean server. There is nothing special about `HashMap` here. Public methods from any public class can be exposed for management in the same way.

    import java.lang.reflect.Method;
    import java.util.HashMap;
    import javax.management.*;
    import javax.management.modelmbean.*;

    // ...

    MBeanServer mbs = MBeanServerFactory.createMBeanServer();
    // The MBean Server

    HashMap map = new HashMap();
    // The resource that will be managed

    // Construct the management interface for the Model MBean
    Method getMethod = HashMap.class.getMethod("get", new Class[] {Object.class});
    ModelMBeanOperationInfo getInfo =
        new ModelMBeanOperationInfo("Get value for key", getMethod);
    ModelMBeanInfo mmbi =
        new ModelMBeanInfoSupport(HashMap.class.getName(),
    			      "Map of keys and values",
    			      null,  // no attributes
    			      null,  // no constructors
    			      new ModelMBeanOperationInfo[] {getInfo},
    			      null); // no notifications

    // Make the Model MBean and link it to the resource
    ModelMBean mmb = new RequiredModelMBean(mmbi);
    mmb.setManagedResource(map, "ObjectReference");

    // Register the Model MBean in the MBean Server
    ObjectName mapName = new ObjectName(":type=Map,name=whatever");
    mbs.registerMBean(mmb, mapName);

    // Resource can evolve independently of the MBean
    map.put("key", "value");

    // Can access the "get" method through the MBean Server
    mbs.invoke(mapName, "get", new Object[] {"key"}, new String[] {Object.class.getName()});
    // returns "value"

## Package Specification

- See the JMX 1.4 Specification PDF document available from the Java Platform documentation on JMX technology

@since 1.5