JMS consists of a set of messaging APIs that enable two types of messaging, publish-and-subscribe (one-to-many) and point-to-point (one-to-one). The highly lucid explanation of the ways in which these work makes the technical content a lot more approachable. In practice, however, Java Message Service is still a book for Java programmers who have some business programming experience. You need the background.
After a simple JMS demonstration in which you create a chat application using both messaging types, the authors dissect JMS message structures, explore both types in detail, and then move on to real-world considerations. These include reliability, security, deployment, and a rundown of various JMS server providers. The appendices list and describe the JMS API, and provide message reference material.
Considering the complexity and reach of the subject matter, Java Message Service does a great job of covering both theory and practice in a surprisingly efficient manner. It's easy to see why JMS has become so popular so quickly. Recommended. --Steve Patient, Amazon.co.uk