JavaSpaces Principles, Patterns and Practice

From the Book: PREFACE: Over the next decade the computing landscape will change dramatically as devices become ubiquitous, network-connected, and ready to communicate. As the landscape changes, the way in which we design and build software will change as well: The distributed application (one that involves multiple processes and devices) will become the natural way we build systems, while the standalone desktop application will become nearly extinct. Designing distributed software is remarkably hard, however. The fundamental characteristics of a networked environment (such as heterogeneity, partial failure, and latency) and the difficulty of gluing together multiple, independent processes into a robust, scalable application present the programmer with many challenges that don't arise when designing and building desktop applications. JavaSpaces(TM) technology is a simple, expressive, and powerful tool that eases the burden of creating distributed applications. Processes are loosely coupled—communicating and synchronizing their activities using a persistent object store called a space, rather than through direct communication. This method of coordinating distributed processes leads to systems that are flexible, scalable, and reliable. While simple, the space-based model is powerful enough to implement advanced distributed applications—from e-commerce systems to groupware to heavy-duty parallel computations. Space-based programming also leverages the Jini(TM) technology's leasing, distributed event, and transaction features, making it suitable for building robust, commercial-quality distributed systems. This book teaches you how touseJavaSpaces technology to design and build distributed applications. It is intended for computer professionals, students, and Java enthusiasts—anyone who wants experience building networked applications. Through experimentation with the code examples, you'll develop a repertoire of useful techniques and patterns for creating space-based systems. We assume that you already have some programming experience and basic working knowledge of Java programming language fundamentals, but this book doesn't require any specific knowledge of network programming. JavaSpaces technology is new, and writing a book before the technology is in widespread use presents a unique challenge. We've approached the project from complementary perspectives. Two of the authors, Eric Freeman and Susanne Hupfer, spent much of the past decade designing and building space-based systems as part of the Linda research group at Yale University and used the JavaSpaces technology during the two years of its development. The third, Ken Arnold, was in charge of the JavaSpaces project at Sun Microsystems, working with a team of engineers to design and build the technology this book is all about. In this book, we present the foundations of programming with JavaSpaces technology, and a set of common patterns and frameworks for approaching space-based programs. As the technology becomes more widely used, the JavaSpace programming community will discover new ways of using it. We would like future editions of this book to incorporate these new patterns, and we invite you to send comments, suggestions, and ideas to javaspaces@awl.com and to make use of the book's web site at ...