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Jini is the name for a distributed computing environment that can offer "network plug and work." A device or a software service can be connected to a network and announce its presence, and clients that wish to use such a service can then locate it and call it to perform tasks. Jini can be used for mobile computing tasks where a service may only be connected to a network for a short time, but it can more generally be used in any network where there is some degree of change. There are many scenarios where this would be useful:

  • A new printer can be connected to the network and announce its presence and capabilities. A client can then use this printer without having to be specially configured to do so.
  • A digital camera can be connected to the network and present a user interface that will not only allow pictures to be taken, but it can also become aware of any printers so that the pictures can be printed.
  • A configuration file that is copied and modified on individual machines can be made into a network service from a single machine, reducing maintenance costs.
  • New capabilities extending existing ones can be added to a running system without disrupting existing services, or without any need to reconfigure clients.
  • Services can announce changes of state, such as when a printer runs out of paper. Listeners, typically of an administrative nature, can watch for these changes and flag them for attention.

Jini is not an acronym for anything, and it does not have a particular meaning. (though it gained a post-hoc interpretation of "Jini Is Not Initials.") A Jini system or federation is a collection of clients and services all communicating by the Jini protocols. Often this will consist of applications written in Java, communicating using the Java Remote Method Invocation mechanism. Although Jini is written in pure Java, neither clients nor services are constrained to be in pure Java. They may include native code methods , act as wrappers around non-Java objects, or even be written in some other language altogether. Jini supplies a "middleware" layer to link services and clients from a variety of sources.


A Programmer[ap]s Guide to Jini Technology
A Programmer[ap]s Guide to Jini Technology
ISBN: 1893115801
Year: 2000
Pages: 189

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