Java Web Start: Difference between revisions

Revision as of 19:17, 22 December 2008

Revision as of 11:10, 3 January 2009

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== Java Network Launching Protocol ==

Programmers often speak of the '''Java Network Launching Protocol''' ('''JNLP''', a closely-related concept) interchangeably with the term "Web Start". The JNLP protocol, defined with an [[XML]] schema, specifies how to launch Java Web Start applications. JNLP consists of a set of rules defining how exactly to implement the launching mechanism. JNLP files include information such as the ___location of the [[Jar (file format)|jar]] package file and the name of the main class for the application, in addition to any other parameters for the program. A properly configured browser passes JNLP files to a Java Runtime Environment (JRE) which in turn downloads the application onto the user's machine and starts executing it. The development of JNLP took place under the [[Java Community Process]] as JSR 56. It includes the original 1.0 release, the subsequent 1.5 maintenance release, and as of [[2006]], the pending 6.0 maintenance release. JNLP is free; developers need not pay a license fee in order to use it in programs.

Important Web Start features include the ability to automatically download and install a JRE in the case where the user does not have Java installed, and for programmers to specify which JRE version a given program needs in order to execute. The user does not have to remain connected to the Internet to execute the downloaded programs, because they execute from a locally-maintained [[cache]]. Updates of the software download from the Web are available when the user is connected to the Internet, thus easing the burden of deployment.