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RIA & Ajax: Article

Desktop Java Slims Down to Enter the AJAX Race

A number of very significant development efforts are underway that bode well for Desktop Java's future

A number of very significant development efforts are underway that bode well for Desktop Java's future.

On the language side is the Java FX script project Java FX is neat because it provides a high-level scripting interface that runs on top of the Java 2D API. From the users' viewpoint it means they don't have to write Java code and, for better or worse, understand the intricacies of threads, Java 2D or Swing class hierarchies, timing frameworks, and so forth. Instead they just write script that describes the desired GUI at a high level, including animation effects, graphic effects such as gradients or noise, and data binding in the base API. There are some nice tools out there to help teach the language syntax that's available on; the goal of the FX team is to provide a syntax and experience that is palatable to graphic designers and folks who are interested in finessing the visual experience of the application. Currently at runtime it operates as a kind of fourth-generation language because an interpreter creates Java code from the FX script and then calls the appropriate Java 2D APIs. The long-term goal of the team though is to compile from FX script straight to byte codes.

On its own Java FX is s a nice addition to the desktop Java stable; however, it still relies on the presence of a JRE that can run the code it generates. To those who see FX as being an entrant into the rich Internet application space, competing with Adobe Flex for example, there remains the difficult problem of how to get the install experience and runtime performance of desktop Java comparable to other rich Internet application architectures. Fortunately this problem is being tackled by another very interesting project, the Java kernel.

The Java kernel initiative recognizes the fact that most Java applications typically use a subset of the JRE, an example being Limewire (a file-sharing client app) that weighs in at about 1/3 of a total JRE size. The kernel will repackage the JRE such that only the portions required to run an app are downloaded as and when they are needed. The base portion that every program needs would be downloaded as a minimum for the JRE to start, and an application can either explicitly specify additional dependencies it needs, or rely on ClassNotFound exception magic to cause missing classes to be downloaded on demand. This is all great news to help slim down and make more efficient a Java program's delivery to a user's desktop. In addition to tackling how Java programs are downloaded, the kernel is also looking at the startup performance of Java programs. While warm start times have decreased significantly over the last few releases, a cold start JRE still requires a delay of many seconds before the application's main(String[]) is called. The Java kernel is attempting to tackle this by effectively turning a cold start experience into a warm one, using techniques such as pre-loading the JRE from disk into memory, as well as having operating system services whose job it is to monitor available memory and JRE activity to get the best performance for the user. In addition to these, the kernel is also providing a new browser plug-in that gives Web start developers more information about what's on the desktop, the available JRE levels and vendors in detail, and generally makes the whole JNLP experience slicker and more robust.

Both the Java kernel and Java FX are great news for Desktop Java. The kernel is good because it's recognizing that Swing has reached a stage of maturity where the problem isn't one of missing features, but how to help developers get their applications onto a user's desktop as quickly and efficiently as possible. FX is great news because it opens up a whole new set of developer to Java; those who are comfortable with scripting languages and want to do advanced animation and graphics effects easily with a few lines of code. The end result of both will be more applications written in Java running on more users' machines, faster and easier for both developer and user.

More Stories By Joe Winchester

Joe Winchester, Editor-in-Chief of Java Developer's Journal, was formerly JDJ's longtime Desktop Technologies Editor and is a software developer working on development tools for IBM in Hursley, UK.

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Most Recent Comments 07/12/07 02:41:37 PM EDT

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