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MBean auto registration

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This example shows how to automatically create and register mbeans using OpenEJB features.

Dependencies

To be able to use it you need to import the mbean api (annotations):

<dependency>
  <groupId>org.apache.openejb</groupId>
  <artifactId>mbean-annotation-api</artifactId>
  <version>4.0.0-beta-1</version>
  <scope>provided</scope>
</dependency>

The MBean

The mbean implements a simple game where the goal is to guess a number.

It allows the user to change the value too.

The registering

To register a MBean using OpenEJB you simply have to specify a property eaiher in system.properties, or in intial context properties.

The example MBean is called org.superbiz.mbean.GuessHowManyMBean so we simply add it to the properties given to the initial context:

Properties properties = new Properties();
properties.setProperty("openejb.user.mbeans.list", GuessHowManyMBean.class.getName());
EJBContainer.createEJBContainer(properties);

The implementation

To implement the org.superbiz.mbean.GuessHowManyMBean MBean you simply annotate the POJO with specific annotations:

@MBean
@Description("play with me to guess a number")
public class GuessHowManyMBean {
    private int value = 0;

    @ManagedAttribute
    @Description("you are cheating!")
    public int getValue() {
        return value;
    }

    @ManagedAttribute
    public void setValue(int value) {
        this.value = value;
    }

    @ManagedOperation
    public String tryValue(int userValue) {
        if (userValue == value) {
            return "winner";
        }
        return "not the correct value, please have another try";
    }
}

Tests

Then simply get the platform server and you can play with parameters and operations:

MBeanServer server = ManagementFactory.getPlatformMBeanServer();
ObjectName objectName = new ObjectName(OBJECT_NAME);
MBeanInfo infos = server.getMBeanInfo(objectName);
assertEquals(0, server.getAttribute(objectName, "value"));
server.setAttribute(objectName, new Attribute("value", 3));
assertEquals(3, server.getAttribute(objectName, "value"));
assertEquals("winner", server.invoke(objectName, "tryValue", new Object[]{3}, null));
assertEquals("not the correct value, please have another try", server.invoke(objectName, "tryValue", new Object[]{2}, null));

Note

If OpenEJB can't find any module it can't start. So to force him to start even if the example has only the mbean as java class, we added a beans.xml file to let OpenEJB find a module.

 

APIs Used

Source

svn co http://svn.apache.org/repos/asf/openejb//examples/mbean-auto-registration
cd mbean-auto-registration
mvn clean install