I have seen the whitepapers for the java source structure but it doesnt say what framework (struts 2, spring etc..) its using.

Example: does it use ORM like hibernate to map the database tables to the class when it generates the code.

Hi, Ron the platform doesn't use any framework, for the view technology it uses a outsystems JSF library that implements all Service Studio controls, and for the db, plain ojdbc.
This other post states basically the same, but I'm putting it here for reference:
Hope this helps answering your question.