Java Distributed Computing

A Basic Collaborative Infrastructure

Before we explore some collaborative applications, let’s take a look at a basic collaborative infrastructure implemented using some of the concepts presented earlier in this book. We’ll build on this infrastructure to illustrate the development of various types of collaborative systems. The framework that we’ll build involves a single mediator (the server) handling interactions among multiple collaborators (clients). Each collaborator has a unique identity, issued by the mediator, and each collaborator can either broadcast messages to all of the collaborators registered with the mediator, or it can send a message to a single collaborator.

One of the first steps in developing a collaborative system is deciding what kind of communications scheme is right for you. We’ve discussed several ways to connect remote agents, including basic socket communications, message passing, RMI remote objects, and CORBA remote objects. To illustrate our basic collaborative system, we’ll show a version based on RMI and remote objects, and another version based on basic message passing. We’ll start with the message-passing version, since this will let us look in detail at some of the dynamics of a distributed system involving many agents working together simultaneously. Then we’ll look at ways to implement the same collaborative infrastructure using remote objects, where the object distribution system assumes responsibility for some of the issues we’ll see in our ...