Java MXBean custom types

Question

I am trying to create an MXBean with a custom attribute, but I get javax.management.NotCompliantMBeanException IJmsDestinationMBean.getAttributes has parameter or return type that cannot be translated into an open type

I have read that MXBean attributes have to be OpenType compatible. How would I make my attribute work this way? All the classes below are in the same package.

class JmsDestinationMBean implements IJmsDestinationMBean{

  protected JmsDestinationAttributes attributes = new JmsDestinationAttributes();

  @Override
  public JmsDestinationAttributes getAttributes() {
    return this.attributes;
  }
}

@MXBean
interface IJmsDestinationMBean {
  JmsDestinationAttributes getAttributes()
}

class JmsDestinationAttributes {

  protected String name
  protected int messagesCurrentCount
  protected int consumersCurrentCount

  String getName() {
    this.name;
  }

  int getMessagesCurrentCount() {
    this.messagesCurrentCount;
  }

  int getConsumersCurrentCount() {
    this.consumersCurrentCount;
  }
}

Answer 1

The problem is the interface IJmsDestinationMBean. It returns a type JmsDestinationAttributes which is not an open type. Here's the rules-of-thumb I follow when doing this:

• The actual registered MBean (which has a complex typed attribute) is called Foo and it's management interface is called FooMXBean.
• The complex type (the attribute of Foo is called Bar and has a management interface called BarMBean. This guy cannot return any values that are not open types or other properly exposed complex types.

So (for this example) the "host" MBean needs to be an MXBean in order to support complex types , and the complex type needs to have an interface called <ClassName>MBean. Note that one has the MXBean interface, and the other has the MBean interface.

Here's my example:

• JMSDestination implements JMSDestinationMXBean
• JmsDestinationAttributes implements JmsDestinationAttributesMBean

...apologies for the loose case standard. It's an on the fly example.

Here the JMSDestination code, with a main to create and register. I am simply using the user name property to provide the name.:

public class JmsDestination implements JmsDestinationMXBean {
    protected JmsDestinationAttributes attrs = new JmsDestinationAttributes(System.getProperty("user.name"));

    public JmsDestinationAttributes getAttributes() {
        return attrs;
    }

    public static void main(String[] args) {
        JmsDestination impl = new JmsDestination();
        try {
            ManagementFactory.getPlatformMBeanServer().registerMBean(impl, new ObjectName("org.jms.impl.test:name=" + impl.attrs.getName()));
            Thread.currentThread().join();
        } catch (Exception ex) {
            ex.printStackTrace(System.err);
        }
    }
}

The JMSDestinationMXBean code:

public interface JmsDestinationMXBean {
    public JmsDestinationAttributes getAttributes();
}

The JmsDestinationAttributes code which uses the same name and random numbers for the values:

public class JmsDestinationAttributes implements JmsDestinationAttributesMBean {
    protected final String name;
    protected final Random random = new Random(System.currentTimeMillis());
    public JmsDestinationAttributes(String name) {
        this.name = name;
    }
    public String getName() {
        return name;
    }

    public int getMessagesCurrentCount() {
        return Math.abs(random.nextInt(100));
    }

    public int getConsumersCurrentCount() {
        return Math.abs(random.nextInt(10));
    }
}

.... and the JmsDestinationAttributesMBean:

public interface JmsDestinationAttributesMBean {
    public String getName();
    public int getMessagesCurrentCount();
    public int getConsumersCurrentCount();
}

The JConsole view looks like this:

The JConsole view of the MXBean's attributes looks like this:

Make sense ?