Next Generation in Applet Java Plug-in Technology

It's time to take another look at Java applet technology for delivering your programs over the web. The Next-Generation Java Plug-in Technology runs applets in a different, more efficient and more reliable way than ever before. Now you can reap the following benefits:

* Improved reliability
* Improved user experience
* Applets launch in the background
* Built-in JNLP support
* Per-applet command line arguments
* Heap size, Java 2D API acceleration options
* Improved Java/JavaScript programming language integration
* Improved Windows Vista support
* Signed applets now work correctly in Protected Mode Internet Explorer

The next-generation Java Plug-in offers a completely redesigned architecture, and is available in the Java SE 6 Update 10. This plug-in provides powerful new capabilities to applets in the web browser, while improving the overall reliability and functionality of applets in a backward-compatible manner.

The most significant new feature of the next-generation Java Plug-in is built-in support for launching applets from JNLP files. Using the JNLP file format as the applet descriptor allows applets to instantly reuse JNLP extensions previously written for Java Web Start applications, and significantly expands the capabilities of applets in many other ways.
A New Way of Executing Applets

The new way of executing applets has architectural similarities to Java Web Start technology, but tighter browser integration. Applets no longer execute in a Java Virtual Machine (JVM) inside the web browser. Instead, a separate JVM machine process is launched to execute applets. By default, only one JVM machine is launched, but you have the opportunity to launch more than one JVM machine, and you get support per-applet command-line arguments, so you can affect heap size or other requests.
Applet Architecture
Figure 1. Applet Architecture


In Figure 1 above, the clouds represent JVM instances. There is a small, headless JVM inside the browser that is used to manage the connections to one or more client JVMs that actually run the applets. In the diagram the Dukes represent applets. One JVM instance is running two applets and the other is running one.

Applets launch directly from JNLP files, make use of the same descriptor used by Java Web Start software, and allow more powerful parameters than the classic “archive", “code", and “cache_archive" parameters.

The new plug-in provides:

* access to advanced JNLP extensions previously available only to Java Web Start software applications. A small set was previously available, with restrictions, and these restrictions have now been removed.
* access to the JNLP APIs from applets.
* PersistenceService, DownloadService.
* control over heap size, command-line arguments, JRE version selection, and auto-download. You have the same capabilities as Java Web Start software for applications.

Source : Dana Nourie and Kenneth Russell,