Using JMX with the Java Message Service - JMX in Action - page 320

received. At this point, the MBean is ready to receive messages from the JMS
message bus.
The onMessage() method handles messages as they are published to the MBean.
Remember that this MBean is interested in only two messages. If either the MOVIE-
LIGHTSOn or MOVIELIGHTSOff message is received, the MBean will execute a macro.
If any other message is received, the MBean will print a message indicating that
it is not interested. To complete a macro, the MBean will invoke its publishMes-
sages() method, passing in the two messages to be sent.
The publishMessages() method uses the JMS bus to send device control messages.
In this method, the MBean looks up the topic in which it will publish messages.
After the topic lookup, it creates a topicPublisher so that it can publish the mes-
sage. After acquiring the topicPublisher , it needs to create a message to publish.
In this case, it will only be using a text message returned from a call to the Topic-
Session object. Before publishing the message, it sets the value of the text mes-
sage using the setText() method. After it has the topic, message, and publisher,
it can publish the message. Using the publish() method in the topicPublisher ,
the MBean publishes both messages to the deviceMessages topic.
Finally, the MBean implements the two methods exposed by its MBean interface.
These methods are directly accessible from the management system by connect-
ing the JMX agent containing the MBean. If you want to turn on or off the home
theater system, you can do so from a management application. These methods
will be useful for testing or diagnosing problems with the message bus.

C

D

E

Constructing the debugging device message listener
(the IR signal transmitter)
Now it is time to write the subscriber class that simulates the IR signal transmit-
ter. This class, shown in listing 13.3, subscribes to the deviceMessages topic and
prints to the screen when it receives messages. This class looks very similar to the
previous MBean class. It will be executed from the command line.

Listing 13.3 DebugSubscriber.java

package jmxbook.ch13;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;

import javax.jms.TopicPublisher;
import javax.jms.TopicConnectionFactory;
import javax.jms.TopicConnection;