Challenges to the national health system related to medical activities financing and quality of care are described. Bulgarian Health Information System design is presented based on the activity-based funding model, international health informatics standards and the common platform for automated programming. Platforms realised by eHealth and IT technology leaders (Ireland, Finland, Oracle USA) are presented. The technical requirements to the National Health Information System (NHIS) are prepared with a focus on domain independent common platform, specialised health components, high scalability, flexibility and reusability. The synergetic use of widely used international health standards for semantic interoperability is presented (ContSys, HISA, EHRCom, and CDR). NHIS common structure is proposed based on cloud computing, SOA and knowledge based automated software engineering (KBASE) complemented with customised components, including kernel, internal healthcare components and external interfaces.

Keywords: SOA, Cloud computing, Knowledge based automated software engineering, common platform for automated programming, eHealth, activity-based funding, health informatics standards, ISO 13940 ContSys, ISO 12967 HISA, ISO 13606 EHRCom, ISO/TS 29585 CDR.