test

Java Dynamic Management Kit 5.0 Tutorial

Running the Notification Forwarding Example

The examplesDir/Notification directory contains all of the files for the broadcaster MBean, the BaseAgent application, and our Client application that is the listener object. To run the notification forwarding example, we use the BaseAgent application that contains an RMI connector server.

To Run the Notification Forwarding Example

  1. Compile all files in this directory with the javac command.

    For example, on the Solaris platform with the Korn shell, type:


    $ cd examplesDir/Notification/
$ javac -classpath classpath *.java

  2. Start the agent on another host or in another terminal window with the following command.

    Be sure that the classes for the NotificationEmitter MBean can be found in its classpath:


    $ java -classpath classpath BaseAgent

  3. Wait for the agent to be completely initialized, then start the manager in another window with the following command, where hostname is the name of the host running the agent.

    If you started the agent on the same host, you can omit the hostname:


    $ java -classpath classpath Client hostname

    When started, the manager application first creates the NotificationEmitter MBean and then registers itself as a listener.

  4. Press Enter when the application pauses to step through the various notification forwarding situations that we have seen in this topic.

  5. Press Enter again in the manager window to exit the application.

    Leave the agent application running if you want to interact with the example through the HTML protocol adaptor of the BaseAgent.

To Interact With the Notification Forwarding Mechanism

  1. Start the manager in another window with the following command, where hostname is the name of the host running the agent.

    If you started the agent on the same host, you can omit the hostname:


    $ java -classpath classpath Client hostname

  2. Load the following URL in your browser and go to the MBean view of the NotificationEmitter MBean:

    If you get an error, you might have to switch off proxies in your browser preference settings. Any browser on your local network can also connect to this agent using this URL.

  3. When the manager application pauses for the first time, call the sendNotifications method from your browser with a small integer as the parameter.

    The listener handles your notifications in the manager's terminal window. Because the manager is still in push mode, they are forwarded immediately.

  4. Press Enter in the manager window.

    The manager is now in pull mode with a pull period of 500 milliseconds.

  5. Through the MBean view, send 1000 notifications.

    If your agent's host is slow enough, or if your manager's host is fast enough, you might be able to see the manager pause briefly after it has processed all notifications from one period and before the next ones are forwarded.

  6. Press Enter in the manager window.

    The agent now forwards notifications by request.

  7. Through the MBean view, send 15 notifications, then press Enter again.

    The manager pulls all of the notifications: the 30 triggered by the manager and the 15 we just triggered. They were all kept in the buffer, waiting for the manager's request to forward them. Remember that the sendNotifications operation resets the sequence numbering every time it is invoked.

  8. Press Enter in the manager's window.

    The cache size is set to 10 notifications and the overflow mode to DISCARD_OLD.

  9. Through the MBean view, send 15 more notifications, then press Enter again.

    Only the last 10 of our notifications fit into the cache buffer. All the rest, including those already triggered by the manager, overflow and are discarded.

  10. Press Enter to see that the discarded notifications are tallied in the overflow count.

  11. Press Enter in the manager's window.

    The cache size is still 10 notifications and the overflow mode is set to DISCARD_NEW.

  12. Through the MBean view, send only 5 more notifications, then press Enter again.

    The first 10 of the manager-triggered notifications are received. All of the more recent notifications, including ours, overflow the cache buffer and are lost.

  13. Press Enter to see that the lost notifications are tallied in the overflow count:

    35 from Step 12 plus 25 more from this step, for a total of 60.

  14. Press Enter in the manager's window again to stop the Client application.

  15. Press Enter in the other window to stop the agent application when you have finished running the example.