[Taken from the JavaSpaces FAQ page]
This technology provides a cooperative marketplace for posting and retrieving groups of related objects across a network. "Buyers" and "Sellers" dynamically post their requests and/or services to a space and receive a response from interested parties. JavaSpaces is not interested in who is posting what; it is based simply on a value-matching lookup routine for specified fields.
The JavaSpaces technology is written in the Java language, and implements the Java RMI extension. It is a simple, fast, and unified mechanism for sharing, coordinating, and communicating distributed resources, services, and objects across a network.
JavaSpaces is based on LindaTupleSpaces.
Info on Sun's JavaSpaces book: JavaSpacesPrinciplesPatternsAndPractice
The official JavaSoft page on JavaSpaces: http://www.javasoft.com/products/javaspaces
The ComponentBus pattern in ComponentDesignPatterns captures the recurring theme of reducing dependencies between components via TupleSpace**s.
See also JiniTechnology, GigaSpaces, SpaceBasedArchitecture