Well maybe I didn't analyzed fully your initial proposal, but
what you're trying to send as a mix of headers and structured data could as well be completely kept as structured data.
maybe exslt:document is limited in the sense that it can't provide
back a return value, but I would far prefer in term of API something
as simple as exslt:document and keep everything as markup rather
than a SOAP oriented API. That API get a tree as input, serialize it
POST it to the target href, and returns the resulting value (a tree
answer). That would be sufficient for XML-RPC driven XSLT interraction.
Simple framework, easy deployment, and everything is kept at the markup
and structure level.

Daniel, I would agree that sending just XML would be sufficient
in theory, so there wouldn't be any need to sending HTTP request
parameters, headers, attributes, etc. But, SOAP/HTTP is specified
to use these things and that's out of my control. What I am
trying to do is to build and interact with SOAP/HTTP complient
servers in XSLT, so, I can't choose not to use HTTP/POST with
all those headers.

I have many things that I don't like about SOAP, basically that it
is not simple. If you have powerful connections into the W3C,
make them do it right :-)

regards
-Gunther

--
Gunther Schadow, M.D., Ph.D.                    gschadow@xxxxxxxxxxxxxxx
Medical Information Scientist      Regenstrief Institute for Health Care
Adjunct Assistant Professor        Indiana University School of Medicine
tel:1(317)630-7960                         http://aurora.regenstrief.org