Java Web Start is an application-deployment technology that includes the portability of applets, the maintainability of servlets and JavaServer Pages (JSP) file technology, and the simplicity of mark-up languages such as XML and HTML. It is a Java application that allows full-featured Java 2 client applications to be launched, deployed and updated from a standard Web server. Upon launching Java Web Start for the first time, you might download new client applications from the Web. Each time you launch JWS thereafter, you can initiate applications either through a link on a Web page or (in Windows) from desktop icons or the Start menu. You can deploy applications quickly using Java Web Start, cache applications on the client machine, and launch applications remotely offline. Additionally, because Java Web Start is built from the J2EE infrastructure, the technology inherits the complete security architecture of the J2EE platform.
The technology underlying Java Web Start is the Java Network Launching Protocol & API (JNLP). Java Web Start is a JNLP client and it reads and parses a JNLP descriptor file (JNLP file). Base on the JNLP descriptor, it downloads appropriate pieces of a client application and any of its dependencies. If any of the pieces of the application are already cached on the client machine, then those components are not downloaded again, unless they have been updated on the server machine. After you download and cache the client application, JWS launches it natively on the client machine.
The following diagram shows an overview of launching a client application, include the Application Client for WebSphere Application Server, Version 6 as a dependent resource, using Java Web Start.
The Web browser running on a client machine connects to a Web application located on a server machine. The client application JNLP descriptor file is downloaded and processed by Java Web Start on the client machine.
Each of these JNLP descriptor files, the client application (JAR or EAR) and the dependent resource JAR files are packaged as Web applications in an EAR file. This EAR file is deployed to an Application server. The client machine with JWS installed uses a Web browser to connect to the url of the client application JNLP descriptor file to download and run the client application.
You can use Java Web Start on the Java 2 Standard Edition Developer Kits that IBM provides, packaged in Application Client for WebSphere Application Server, Version 6; Java Web Start on Sun Microsystems J2SE Software Development Kit or J2SE Java Runtime Environment 1.4.2, which you can download from the Sun Microsystems Web site for Windows, Linux and Solaris operating systems, or the Java Web Start on HP SDK or RTE for Java 2 version 1.4.2, which you can download from the HP Web site.
Related concepts
Client application Java Network Launcher Protocol deployment descriptor
file
Related tasks
Preparing the Application Client run-time dependency component for
Java Web Start
Preparing Application Clients run-time library component for Java Web
Start
Related information
Java Web Start 1.4.2 documentation
Java Web Start frequently asked questions