Writing MBeans

Use this procedure to learn how to instrument a resource by providing a standard MBean. However, there are some limitations in the naming of the MBean interface, which sometimes make it impossible to write a standard MBean. For that reason the JMX™ 1.2 Specification introduces a wrapper class StandardMBean , which itself is a dynamic MBean that takes the managed object and the MBean interface as parameters. By using the StandardMBean no restrictions on class/interface names exist any more.

1. Specify in the MBean interface all attributes and operations that you want to be manageable by the MBeanServer:

   /**
   *The MBean interface
   */
   public interface TestResourceMBean {
     public String anOperation(String parameter);
   }
   /**
   * The managed object
   *
   * @see TestResourceMBean
   */
    
   public class TestResource implements TestResourceMBean {
     // visible for management clients
     public String anOperation(String parameter) {
     // not visible for management clients
        return echoOperation (parameter);
     }
     // not visible for management clients
    
     public String echoOperation(String string) {
        return string
     }
   }

 

The standard MBean management interface is discovered according to an inheritance pattern upon registration. For more information, see the JMX™ 1.2 Specification on http://java.sun.com.

1. Set the wrapper class StandardMBean :

   // the MBean interface
   interface Foo {
     public String anOperation(String);
   }
   // the managed object
   class MyResource implements Foo {
     // visible for management clients
     public String anOperation(String);
     // not visible for management clients
     public String anotherOperation(String);
   }
   import javax.management.StandardMBean;
   ...
   // instantiate the MBean
   StandardMBean mBean = new StandardMBean(new MyResource, Foo.class);

 

It is sometimes necessary to subclass the managed object from StandardMBean instead of passing it as a parameter to the constructor. This is the case if the managed object wants to implement the NotificationBroadcaster or MBeanRegistration interfaces, or must be instantiated by a remote MBeanServer.

For more information, see the API documentation of javax.management.StandardMBean and com.sap.pj.jmx.mbeaninfo.StandardMBeanWrapper . The latter allows for provision of additional meta data attached to the MBeanInfo .