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Java 6u10 is the biggest update release ... of Java we have ever shipped, and the fact that there are no public API changes doesn't mean that you won't see anything to be excited about....

Ethan Nicholas, a key engineer behind many of the new features in Sun's next-generation JRE, shares more details of Java 6 Update 10 in Introducing Java 6 update 10.

While Java updates don't introduce new APIs, nor changes to existing APIs, Nicholas notes that:

Java 6 update 10 is a very different animal than the updates that preceded it. Java 6u10 pushes the envelope by adding more new features and functionality than in any previous Java programming language update release, including many that have been a long time coming...

The most immediately beneficial new feature, especially to developers and Java end-users, is a slimmer JRE download. Using a distribution mechanism that allows for the incremental download of the entire JRE, the initial download size for a typical Swing application ranges between 4-5 MB:

In the current build, the typical download size for Swing programs and Java applets is on the order of 4-5MB, compared to 14.4MB for the full JRE.

Applets also received a major architectural boost by running them outside the browser's process:

The next-generation plug-in runs applets outside of the browser in one or more separate processes. Applets still appear inside of the web browser window as they always have, but this means that it is now possible to use different JRE versions, command-line arguments, and configurations to run different applets...

The isolation provided by running the web browser and the JRE -- two very large, very complex pieces of software -- in separate process spaces improves the reliability of both, and gives applets the same flexibility and control over JRE configurations that other Java software has always enjoyed.

The way Update 10 achieves this is by allowing applets to take advantage of the same JRE hooks desktop JNLP applications have. As a side-benefit, applets can easily be turned into desktop applications, and vice versa, a desktop application can be deployed inside the browser:

With very little additional work, you can now deploy the same program as both an applet and a Web Start program, and still take advantage of JNLP services such as PersistanceService and FileSaveService.

In addition, applet deployment is aided by a new JavaScript library, simplifying applet inclusion in page:

The following HTML code is all it takes to ensure that Java 1.6 is installed and then a Java applet is launched:

  deployJava.runApplet({codebase:"http://www.example.com/applets/",
     archive:"ExampleApplet.jar", code:"Main.class",
     width:"320", Height:"400"}, null, "1.6");

Nicholas also discusses Nimbus, the new Swing look and feel:

A brand new, modern look and feel based on Synth, Nimbus provides a polished look to applications which choose to use it. And because Nimbus is drawn entirely using Java 2D vector graphics, rather than static bitmaps, it's tiny (only 56KB!) and can be rendered at arbitrary resolutions.

In the article, Nicholas also talks about the default settings for the Pack200 compression, as well as a streamlined JRE updater.

Do you think these new features are sufficient to cause a desktop Java comeback?