XML access for relational data...

Hi!
We are designing a new database application whose job it is to collect and provide data (structured and BLOB) to different departments. The access method is to be http.
I hesitate to actually /store/ the data as XML but would like to offer it as xml.
The idea is to provide a RESTful interface so that GET/PUT/POST/DELETE requests do their actions. However, so far I'm a bit stumped because I see no way to
- use XMLDB to process the queries according to /my/ code (in

   particular any URL parsing and parameter processing)
- offer XML data without /loading/ it into XMLDB as XML data.
Does anyone know how to solve these issues?

I'd like to keep the relational structure because of all the constraints, triggers, referential integrity, data change notification and so on. Also, we will reference data held in other, also conventional schemas.

If possible at all I'd like to avoid putting the XML/Table mapping into the application server.

We are using 10gR2, about 50 users, a normal LAN and probably less than 50GB of data.

Lots of Greetings!
Volker

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