Looking for Good Java & XML for RPG Info

I currently know how to use java in RPG, however I have never had the 
opportunity to use XML in RPG yet.  I have a case where I am wanting RPG to use 
both Java and XML, possibly having RPG create XML documents to pass to Java, 
and receiving other XML documents from java to have RPG parse.

Does anyone have any good links to documentation on where to begin to learn 
this? I learn best by simple, straight-to-the-point examples.  I also know IBM 
has a XML service program available for RPG, but I don't have a clue how to use 
it. I haven't found any material out there that makes sense to a beginner in 
this area (but I don't want it to be over simplified where it can't be applied 
in a real world business environment). I know the basic concept of XML, I just 
don't know how to program with it, especially in RPG. I am experienced in java 
programming.

Thanks for any direction anyone with exposure to this can provide.