JWS Downsides

Appendix B. Installation Using Java Web Start

ava Web Start (JWS) is a web-enabled installer for Java applications (http://java.sun.com/products/javawebstart/). Typically, the user points a browser at a page containing a link to a deployment file; the retrieval of that file triggers the execution of JWS on the client, which takes over from the browser.

This assumes that JWS is present on the target machine.

JWS uses the information in the deployment file to download the various JAR files making up the application, together with installation icons, a splash screen, and other details. The application is stored in a local cache and executed inside a JVM sandbox. Subsequent executions of the application utilize the cached copy unless the original has been modified, in which case the changed JARs are downloaded again.

This appendix shows how the BugRunner and Checkers3D applications in Chapters 11 and 15 can be deployed with JWS. BugRunner is the beginnings of a 2D arcade-style game but uses the Java 3D timer. Checkers3D is a basic Java 3D application that displays a blue sphere floating above a checkerboard surface.

Both applications require native libraries, and I'll cover how JWS installers suitable for Windows can be created. However, JWS is a cross-platform tool, so I'll briefly examine the issues in making BugRunner and Checkers3D work on the Linux and Mac operating systems.

Deployment links are usually placed in a JWS portal page, a page using JavaScript and VBScript to detect whether the intended client platform possesses JWS. If JWS isn't found, then it needs to be downloaded before the application installation can begin. I'll use a portal page for accessing BugRunner and Checkers3D, located at http://fivedots.coe.psu.ac.th/~ad/jws/.

JWS uses digital signing and certificates to secure applications, so I'll finish by looking at how to use third-party certificates.