Liberty: Examples of registering MBeans

Any application can register an MBean by using an MBeanServer instance. Suppose that an application contains a class that is called org.example.Example that implements the interface org.example.ExampleMBean, which defines some attributes and operations. As in the following example, the application might simply instantiate the Example class then register it using a unique ObjectName. If the ObjectName chosen is already in use, a javax.management.InstanceAlreadyExistsException is reported.

import java.lang.management.ManagementFactory;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import org.example.Example;

...

MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
Object mbean = new Example();
ObjectName name = new ObjectName("org.example.MyApplication:name=Example");
mbs.registerMBean(mbean, name);

In addition, an application might register an MBean that extends java.lang.ClassLoader and provides access to any number of MBean implementation classes. Then, you can use any other JMX client, local or remote, to create and register MBeans provided by the application. For example, suppose that the application has an MBean class org.example.ApplicationClassLoader that performs the following tasks:

• Implements any empty interface org.example.ApplicationClassLoaderMBean
• Extends java.lang.Classloader, and
• Provides access to the org.example.Example MBean implementation class

The application can register an instance of ApplicationClassLoader to make the Example MBean available to other JMX clients as follows:

import java.lang.management.ManagementFactory;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import org.example.ApplicationClassLoader;

...

MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
Object classLoader = new ApplicationClassLoader();
ObjectName name = new ObjectName("org.example.MyApplication:name=ClassLoader");
mbs.registerMBean(classLoader, name);

Any JMX client can create an Example instance. The following example assumes that the variable mbs is an MBeanServer or MBeanServerConnection instance. See Working with JMX MBeans on Liberty.

import javax.management.ObjectName;

...

ObjectName loaderName = new ObjectName("org.example.MyApplication:name=ClassLoader");
ObjectName exampleName = new ObjectName("org.example.MyApplication:name=Example");
mbs.createMBean("org.example.Example", exampleName, loaderName);