OntoDL Introduction: FHIR, CTS2, CTS2-LE and OntoDL

The OntoDL interpreter translates OntoDL defined vocabularies into HL7 FHIR ValueSet Resources. The generated resource definitions are rendered as XML and written to the file system. From there they can be loaded into any Terminology Server that implements a loader for FHIR resouces.

CTS2 and CTS2-LE

From the OntoDL perspective FHIR is only considered as an exchange format while the underlying OntoDL object model is based on the much more powerful CTS2 terminology services standard which allows for managing complex and extensible ontologies. E.g. while the recent FHIR version (DSTU-2) does not provide build-in mechanisms for semanticaly defined, poly-hierarchical ontologies and custom properties, such features are available with OntoDL. In order to make these features available to ontology developers, OntoDL is optimized for being used in conjunction with the Fraunhofer FOKUS CTS2-LE terminology server. CTS2-LE implements the CTS2 data model on top of RDF so that ontologies with semantically tagged edges and fully networked information models can be expressed. The CTS2-LE FHIR loader uses the extension mechanisms of FHIR and defines additional resources and elements for expressing custonm properties and arbitrary concept relationships. All ontologies defined with OntoDL can be loaded into CTS2-LE using the standard CTS2-LE FHIR loader.

Ready for FHIR STU-3

The above mentioned CTS2-LE features (custom properties and predicates) will be part of FHIR STU-3 which is recently balloted. As soon as this version of FHIR is released, OntoDL will allow for transforming OntoDL definitions into both FHIR STU-2 and STU-3. A system parameter will be provided that allows you to control whether OntoDL generated FHIR STU-2 or STU-3 compliant terminologies and value sets:

set FHIR.Version = STU-3

Placing this statement into your existing OntoDL document will automatically generate STU-3 code from an OntoDL definition that was originally written for STU-2.