Adding applet support to Qt/KDE apps

Like everyone else, I want to have Java applet support in KFM. This is related to porting the toolkit, but can be worked on
independently. Here are my current thoughts on the subject:

I would like to have a KJavaAppletWidget class. This would be a C++ class that extends QWidget and displays a Java applet. The class would hide the details of the communication between Java and C++, and would have a fairly trivial API for users. Once such a widget exists adding Java applets support to an application would be trivial - the problem of course is how to write the widget...

I can see two main approaches: one is to use the Java invocation API to load a JVM into the process of the application, the other is to have a Java server that runs in a separate process. I'll refer to the first as 'in-process', and the second as 'out-of-process'.

In process	Out of process
Have to contend with threading issues	No threading problems
JVM crash will kill KFM	JVM crash easy to handle
JVM load may block UI	No problem
JVM cannot be unloaded	JVM unload by killing child process
Fairly easy to communicate with the JVM (JNI)	Need custom communication mechanism

I think the out of process design is better, the main difficulty is the communication between the application and the embedded applet. Displaying the applet window inside a KJavaApplet widget is fairly easy to achieve using swallowing.

Things the application sends to the applet:

Applet parameters, codebase, docbase etc.
start() and stop() calls
Proxy settings (via system properties table)
refresh() reload()
javascript calls to java objects (LiveConnect)
init() destroy()