By now you should have a sense that space-based communication and coordination is a highly flexible and natural match to the plug-and-play nature of the Jini networked environment, where entities come and go. This point will be reinforced as Eric and I cover leasing and transactions later in the series.
About the author
Susanne Hupfer recently coauthored JavaSpaces Principles, Patterns, and Practice with Eric Freeman and Ken Arnold. It is the official Sun Microsystems Jini Series book on the JavaSpaces distributed computing technology. Hupfer is the senior software engineer at Mirror Worlds Technologies, a Java- and Jini-based software applications company. In addition, Hupfer is the research affiliate at Yale University's Department of Computer Science, where she completed her Ph.D. in space-based systems. She would like to thank Freeman for his insights on the Jini game service example and Peter Sparago for his thoughtful review of the article.
For an exploration of space-based programming concepts and code examples, as well as an in-depth look at the JavaSpaces technology APIs, refer to Sun's official Jini Technology Series book on the topic: JavaSpaces Principles, Patterns, and Practice, Eric Freeman, Susanne Hupfer, and Ken Arnold (Addison-Wesley, 1999): http://www.amazon.com/exec/obidos/ASIN/0201309556
You may wish to experiment with the code from JavaSpaces Principles, Patterns, and Practice, which can be downloaded from the book's Website: http://java.sun.com/docs/books/jini
The Jini specifications from Sun Microsystems are the definitive references on the JavaSpaces API (starting with the Jini entry specification and the JavaSpaces specification): http://www.sun.com/jini/specs
The Jini specifications are also provided in The Jini Specification -- another Jini Technology Series book -- by Ken Arnold, Bryan O'Sullivan, Robert W. Scheifler, Jim Waldo, and Ann Wollrath (Addison-Wesley, 1999): http://www.amazon.com/exec/obidos/ASIN/0201616343
Whether you wish to share information with other developers (including the Sun engineers that developed the Jini and JavaSpaces technologies) or seek troubleshooting advice, the official JavaSpaces users mailing list is the place to go: http://archives.java.sun.com/archives/javaspaces-users.html
ITworld.com sends out a weekly Jini Advisor newsletter, written by Eric Freeman, that covers many of the nuances of Jini and JavaSpaces technology (past topics have included codebase, leasing, and transactions): http://www.itworld.com/cgi-bin/w3-msql/newsletters/subcontent12.html