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Java Web Start to the rescue

Find out how Java Web Start aids client-side deployment

By Raghavan N. Srinivas, JavaWorld.com, 07/06/01

Page 2 of 7

Many of these issues are solved via the Java Plug-in. However, even with the Java Plug-in, the user interaction remains constrained by the application hosting the applet.

Java conquers the server turf

Java morphed from an applet-based language, as descried above, into the programming platform of choice on the server. The language's focus shifted heavily from the client to the server side. Using server-based technologies, it was easier from a program maintenance viewpoint to control from the server the user interface for the client. The user interface centers around markup technologies like HTML, XML, XHTML, and so on. Servlets and JSPs are Java-based technologies on the server side that can be used to serve up markup languages. Servlets and JSPs are an important part of J2EE, providing an entry point to the Web clients for other Java- and J2EE-related technologies on the server.

The server-centric approach offers a responsive user interface, albeit with interactivity limited by the markup language used for the client. An advantage of this approach: support for multiple kinds of clients, especially thin clients. Although the interactivity of many of these thin clients is inherently constrained by the nature of the device, thin clients typically can support one or more markup language.

Java comes back on the client

We looked at applets and then at Servlet/JSP-based technologies as the basis for Web client design. These technologies are primarily constrained by the environment in which they are hosted -- a browser or some similar technology. Although this may not prove to be a serious limitation to some applications, it is likely to limit many. A browser-based email client serves as a good example. Although browser-based email clients are quite popular, traditional email clients are more prevalent, especially in the workplace, where there is a need to sift through lots of email, apply filters, and be able to work offline in certain scenarios.

Java Web Start overcomes these user interface and connectivity limitations, and offers client-side software distribution features as well. The availability of Java Web Start on a number of different platforms makes it a powerful choice for designing desktop clients. For instance, you can use Java Web Start to add more interactive clients for J2EE applications.

Some of the ease-of-use and ease-of-programming features associated with Java Web Start include:

• Portability: Java Web Start is available on Windows, Solaris, and Linux, and is expected to be ported to other platforms.
• Caching: Applications launched with Java Web Start are cached locally. Thus, an already-downloaded application is launched on par with a traditionally installed application.
• Maintainability: If the remote application is updated, Java Web Start updates the locally cached version at the application's next invocation.
• Easy launching: Java Web Start allows applications to be launched independently of a Web browser. The application can also be launched through desktop shortcuts, making launching the Web-deployed application similar to launching a native application.
• Ability to work offline: An application can be used in situations where launching through the browser is inconvenient or impossible.

The table below compares the different technologies used for designing Web clients. These different factors influence the design of these Web clients.

 

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