Java Web Start: Difference between revisions

Revision as of 19:08, 16 December 2005

Revision as of 19:23, 16 December 2005

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[[Image:Apple Java Web Start.png|right|Apple's Java Web Start]]

'''Java Web Start''' is a framework developed by [[Sun Microsystems]] that enables starting [[Java programming language|Java]] applications directly from the [[World Wide Web|web]] using a [[web browser|browser]]. Unlike [[Java applet]]s, Web Start applications do not run inside the browser, and the [[Sandbox (security)|sandbox]] in which they run does not have to be as restricted, although this can be configured. One chief advantage of Web Start over applets is that they overcome many compatibility problems with browsers' Java [[plugin]]s and different [[Java virtual machine|JVM]] versions. On the other hand, Web Start programs cannot communicate with the browser as easily as applets. To assist migration a Java Applet can also be used as a java web start application.

Web Start also provides a series of classes in javax.jnlp which provide various services to Java Web Startthe applicationsapplication. ManyMost of these services are designed around the idea of allowing carefully controlled access to resources (such as files and the system clipboard) without giving the Java Web Start application the ability to do what it likes with those resources.

Version 1.0 of Web Start was introduced by Sun in March [[2001]], and ever since [[Java 2 Platform, Standard Edition|J2SE]] version 1.4 it has been included by default with the Java Runtime Environment (JRE) and does not have to be installed separately.

'''JNLP''' ('''Java Network Launching Protocol''') is a closely-related concept that is often used interchangeably with the term "Web Start." It is the protocol, defined as an [[XML]] file format, that specifies how Java Web Start applications are started. 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. With the right browser configuration, JNLP files are passed to a Java Runtime Environment which in turn downloads the application onto the user's machine and starts executing it. In addition to launching standalone applications, JNLP can be used to start Java Applets.

Important Web Start features include the ability to automatically download and install JRE's in case the user does not have Java installed (although this does not work with every browser and platform), and for programmers to specify which JRE version is needed to run a given program. Also, the user doesn't have to remain connected to the Internet to execute the downloaded programs, because they execute from a locally-maintained [[Cache|cache]]. Finally, automatic updates of the software from the Web is available when the user is connected to the Internet, thus easing the burden of deployment.