The JNLP Deployment File

JWS Benefits

JWS works the same way across multiple platforms unlike the downloading and execution of applets, which is plagued by irritating variations between browsers. The headaches caused by browsers' nonstandard programming frameworks (such as JavaScript and HTML variants on different platforms and browsers) are one reason for the decline in popularity of complex applets and the growth in thin clients linked to J2EE-built servers.

Client-side caching avoids an essential problem familiar from applets, which is the need to download an applet every time it's used. That's a waste of bandwidth if the applet hasn't changed and further discourages the development of large applets. JWS suffers from network overheads during the first download, but the copy of the application in the local cache is used after that until changes are detected in the original. This cached copy means network failure doesn't stop the application from executing unless it requires network access for specific tasks. By comparison, an applet is out of reach when the network is down.

JWS only retrieves Java software packaged as JARs. However, the JARs may contain native libraries for different operating systems and platforms, a feature you'll need to utilize the Java 3D libraries. My examples concentrate on Java applications retrieved by JWS, but applets can be downloaded as well.

JWS prevents hacker attacks by executing the installed code inside a sandbox, stopping antisocial behavior such as hard disk wiping or spamming from your machine. Sometimes the security restrictions can be too harsh, and JWS offers two ways of relaxing them: the Java Network Launching Protocol (JNLP) API supports controlled ways to interact with the OS, such as reading and writing files and accessing the clipboard; the second way is to sign software digitally, permitting its security level to be reduced. I'll detail this latter approach, which is mandatory if a program uses native libraries.

Since the downloaded application is running free of the browser, there's complete freedom over the kinds of user interaction and GUI elements that can be employed.