This book is a thorough introduction to Java Message Service (JMS), the standard Java application program interface (API) from Sun Microsystems that supports the formal communication known as "messaging" between networked computers. JMS provides a common interface to standard messaging protocols and to special messaging services in support of Java programs. Messaging involves crucial data exchange between computers, and is often used to coordinate programs in dissimilar systems or different programming languages. Using the JMS interface, a programmer can invoke the messaging services of IBM's MQSeries, Progress Software's SonicMQ, and other popular messaging product vendors. JMS also supports messages that contain serialized Java objects or Extensible Markup Language (XML) pages. Java Message Service shows how to build applications using the point-to-point and publish-and-subscribe models; use features like transactions and durable subscriptions to make an application reliable; and use messaging within Enterprise JavaBeans. It introduces a new EJB type, the MessageDrivenBean, that is part of EJB 2.0, and discusses integration of messaging into J2EE.