Using JMX with the Java Message Service - JMX in Action - page 312

In this chapter, you will combine JMX technology with the Java Message Service
( JMS ). JMS is part of the J2EE platform and provides enterprise messaging for J2EE
applications. This chapter uses a simple example to show how you can add func-
tionality to JMS applications using MBeans. In addition, the example shows how
MBeans can give you a view into the messaging of a JMS application for diagnostics
and management.
13.1 T he Java Message Service
Enterprise messaging is an essential tool for building enterprise applications. It
provides a standard way for applications to communicate in an asynchronous
fashion. JMS supports two models of messaging: Point-to-Point and Publish-
Subscribe. Point-to-Point messaging lets a sender send a message to a single
recipient, whereas Publish-Subscribe allows a sender to “broadcast” a message to
several recipients. In both cases, the message sender and message receiver behave
in an asynchronous manner, meaning that the receiver does not necessarily have
to be present when the message is sent.
In the Point-to-Point model, the message is queued for later consumption. In
Publish-Subscribe mode, a consumer can choose two different types of subscrip-
tion. A durable subscription ensures a consumer will receive all messages that are
published, because all published messages will be queued by the JMS provider
until retrieved. Alternatively, with a normal subscription, the subscriber must be
present and subscribed to receive published messages. In this chapter, we will use
Publish-Subscribe with a normal subscription.
In Publish-Subscribe mode, applications observe topics. A topic is the destina-
tion for a set of messages. JMS clients publish and/or subscribe to a particular
topic for message connectivity.
JMS implementations adhere to the interfaces defined in the J2EE platform.
When developing JMS applications, you write your code according to the inter-
faces. The only difference between JMS implementations is the way you deploy
your applications. (If you need more information about JMS , go to http://
www.javasoft.com.)
13.2 Combining JMX with JMS
Combining JMS and JMX opens many possibilities for Java applications. Using
JMS , you can transform your management system so that it acts as a driver for
your applications. It can also receive messages indicating the health of an