When using raw RO SDK you’ll need to define returned data structures too
You might also look at Data Abstract where it is easier to perform data access/update operations and send/receive datasets. For 3rd party integration it is possible to expose data in JSON format.
Btw which platform do you want to use for server app - .NET or Delphi?
We ship OlympiaServer - an out-of-process session manager. Also there is a sample shipped with RemObjects SDK where a db-based SessionManager is used.