Java Distributed Computing

Chapter 6. Message-Passing Systems

In this chapter we examine applications that use message-passing schemes to distribute information between agents in a distributed system. The first thing we’ll do is define what we mean by “message passing,” then we’ll look at some ways that messages can be handled by a Java agent. We’ll build two versions of a message-passing system. The first is based on a homegrown message-handling system, with Message objects being transmitted over I/O streams between MessageHandlers. Most of our discussion about message passing will be based on these classes. Near the end of the chapter, we’ll look at a message-passing system based on the delegation event model built into the JDK and used by the AWT package. In this case, we’ll be using EventObjects as our messages, and leveraging the model of event sources and listeners from the JDK to build a message-handling framework.