MDM: Patient Repository

Hi,
I am looking to define an architecture combining both IRISforHealth's FHIR server and HAPI's MDM capabilities. Is there anyone who has already implemented this type of solution?
The goal is to implement a single patient repository for multiple hospitals, so HAPI MDM is really interesting.
From what I've seen, some of the issues may be around compatibility between Caché and Hybernate.

Thanks