Perfect Match - Java and RPG and User Spaces?

The recent discussions ("Strategic Java Usage", "Mixed RPG/Java
Performance", "EJB versus RPG/COBOL") have peaked my interest immensely,
thanks for everyone's comments!

I am working on a Java/RPG solution that will be used to get our iSeries
machines into an HTTP SOA (Service Oriented Architecture) type model.  I
have created web services with RPG programs, but parsing XML just isn't
RPG's forte, even with IBM's parser and my wrapper that I wrote for it.

I have recently been looking at having Java do all HTTP communication and
XML parsing and once an XML document had been parsed into the appropriate
"object" it would then be passed to a "Mediator" that would decide what RPG
business logic program needed to be called based on the XML's envelope
contents.  The kind of XML documents I am talking about are anything from
simple requests like "getItem" to something quite large like
"PurchaseOrderRequest".  

Being that I need to pass large amounts of data from Java to RPG I have been
looking for different ways that both can easily talk to each other.  The
model I am planning on using for this is to write the parsed information to
a "smart" User Space for the RPG program to pick up after the Java program
has notified it that there is something available.  By "smart" User Space I
simply mean I have come up with my own method of defining an object sort of
structure within the User Space.  Each set of data in the User Space is
prefixed with the name of that chunk of data and the size that it takes up.
Here is the code for the "smart" user space that I have built:
http://mowyourlawn.com/files/UsrSpc/USRSPCFN.RPGLE  along with an example:
http://mowyourlawn.com/files/UsrSpc/USRSPC.RPGLE

The things that I am wondering about are if this is an efficient method that
may give me performance problems in the future.  Or should I go to a
different method like socket connections?  Any insight on how to make this
Java/RPG relationship work beautifully would be greatly appreciated.  I hope
I have explained what I am trying to do, it is basically what others have
stated in the most recent discussions.

TIA,
Aaron Bartell