I love Java Web Start.  I think it does a very good job of solving many of the Java distribution issues.  It supports automatic updating of apps at the jar level, including dependencies.  It really makes life easy for the end user, and really is pretty easy to implement for the developer.

But, if you are running Ubuntu Linux for AMD64 like I am, it won't work out of the box with the 64 bit JVM.  For whatever reason, Sun hasn't ported it.  Not that I'm complaining.  Now that Sun freed Java, we all have no one to blame but ourselves.

First, let me say, there are more issues for Beryl/Compiz users.  The information below won't help you.  I'll cover running Swing and Java Web Start on Beryl in a separate post later this week.

The solution is to install the 32 bit Java 1.5.  I realize Java 1.6 is available, but it won't work for some reason (I couldn't really tell why, the app just never comes up, but shows no errors).  The installation is pretty simple.  Just run:

sudo apt-get install ia32-sun-java5-bin

Then, you can launch Java web start apps using:

/usr/lib/jvm/ia32-java-1.5.0-sun/bin/javaws http://argouml-downloads.tigris.org/jws/argouml-0.24.jnlp

That example uses ArgoUML .24 but you can easily adjust.

Wrapper Script

You may not want to have to remember all that every time.  I have an easy fix.  Create a wrapper script:

sudo gedit /usr/local/bin/javaws

In the script place:

#! /bin/sh

/usr/lib/jvm/ia32-java-1.5.0-sun/bin/javaws $1

Or, you can just download mine.  Just make sure to set it as executable:

sudo chmod +x /usr/local/bin/javaws

Firefox Integration

In Firefox, when you click on a Java Web Start link, it will prompt you.  You can tell it to open with  /usr/lib/jvm/ia32-java-1.5.0-sun/bin/javaws or simply "javaws" if you created the wrapper script.  You can also check the "Do this automatically..." checkbox.  From that point on, .jnlp links will just work.