*** Draft *** Information architecture: meeting past and current HL7 requirements A project of OMG and HL7 Report May 27 th 2009 Dave Carlson and Jobst Landgrebe

*** Draft *** Contents  HL7 requirements and existing solution  Alternative approach: VA/IBM OHT UML tooling  Project mission proposal

*** Draft *** HL7 v3 was developed to provide a basis for semantic interoperability in the health domain 1.HL7 mission (paraphrased)  Provide foundation to create instances of semantic interoperability within and between organisations in the health care industry 2.Traditional HL7 paradigm  Messaging-based interoperability: based on a reference information model, design model derived messages (wrapper and payload) to exchange health data in a semantically robust fashion  Prescriptive standard for health domain messages with standardised message wrapper, payload information model with health care data types, controlled terminologies and value set (=concept and concept designation sets) bindings 3.Recent HL7 SAEAF paradigm shift  Move away from messaging-based interoperability to interoperability based on enterprise architecture HL7 core functional requirements

*** Draft *** HL7 now desires to broaden adoption by using horizontal tools and composed information models 1. Scale up adoption and usage of HL7 by enabling horizontal tooling (stated by the HL7 Board, TSC and CTO)  Enable broader usage of HL7, reduce costs of HL7 implementation and adoption by using the vast array of standard horizontal tools  Enable HL7 to use standard off-the-shelf tools supporting horizontal standards from organisations such as OMG and W3C, e.g. UML, XMI, OWL  Resolve documentation and “rare specialist knowledge problem”: today, HL7 adoption is hampered by complexity of proprietary tools, lack of easily accessible documentation and scarceness of experts; steep learning curve for “horizontal engineers” due to HL7-specific solutions 2. Remove road-blocks for adoption by allowing composed models (stated by key HL7 stakeholders)  Enable semantic interoperability without enforcing monolithic domain analysis models reflecting only one view  React flexibly to de-centralised, local and evolving user requirements without inflicting costly architectural and technological changes.  Allow many different views of a domain in parallel which can be machine- reconciled HL7 recent quality requirements

*** Draft *** This project was initiated because HL7 can only partially realize its functional and quality requirements High level hypotheses on possible requirement realisation impediments 1) HL7 characteristicDetailed propertiesConsequences for requirements realization HL7 modelling approach Based on speech-act theory, very small set of foundational classes in RIM Basic information modelling very complex due to small set of foundational classes; modelling of entities existing over time difficult; no separation of process-like acts and secondary acts (documentation), counterintuitive modelling of roles HL7 constraining/cloning approach Specialisation (inheritance relationship) modelled with attribute deletion instead of OO- style attribute addition is used to derive classes in the model hierarchy of HL7 (model element provenance relationships) cloning approach to produce multitude of derived classes Barrier to usage of MOF-derived languages if lineages between models and within-model specialisations are to be represented in computable form within the MOF family of languages Usage of EMF impaired (Dave pls give more details) due to cloning approach HL7 vocabulary model No clear separation of concept meaning and concept designation High complexity in value set design HL7 model hierarchyHL7 uses a hierarchical approach of derived models, no architectural design for composition Composed model requirement cannot be met 1) Not complete

*** Draft *** HL7’s current solution, the MIF, fulfills various HL7 requirements beyond modeling 1.Static models: representation of static HL7 information models and their provenance lineage as well as the vocabulary bindings 2.Vocabulary metamodel: representation of the vocabulary metamodel describing the way the vocabulary entities relate to each-other 3.Dynamic models (to be abolished): Modeling of the behaviour of message sending and receiving systems – to be replaced by behavioural framework of SAEAF project 4.Publishing: Publishing of HL7 standards in the HL7 ballot 5.Graphical notation: Data and metadata enabling the creation of graphical model representations ➞ Taken together, the MIF is the current solution of HL7 and is successfully addressing many needs. However, not all HL7 requirements (esp. the non- functional requirements) are fulfilled by it ➞ H7’s main asset it the thorough domain semantics analysis expressed by the current models Requirements fulfilled by HL7 v3 MIF

*** Draft *** HL7’s critique of XMI may confound the quality of a standard with implementation conformance  HL7 states that XMI is a “difficult standard”  However, the problem seems to be a lack of compliance of implementers rather than of the standard itself  All the HL7 tooling used to create XML schema is based on XSLT; the tooling is unable to deal with XMI. XMI is a model packaging and transport format, not a transformation input pattern (this aspect is covered by QVT in the MDA methodology).  XSLT legacy tooling is an impediment to usage of XMI which weighs probably as strong as the OO-contradictory specialisation approach: HL7 is facing barriers to horizontal tooling based on the modeling methodology and the existing tooling HL7 critique of XMI – possible issues

*** Draft *** Contents  HL7 requirements and existing solution  Alternative approach: VA/IBM OHT UML tooling  Project mission proposal

*** Draft *** Open Health Tools (OHT) UML Modeling Tools Project Project jointly managed by VHA and IBM – Open source modeling environment for creation and implementation of healthcare standards – All tools built on Eclipse Modeling EMF and MDT for the first release – Full open source stack, or components for commercial modeling tools Planned scope includes: – Information models Initially, HL7 static model. Researching HITSP, X12, NCPDP and others UML with stereotype extensions and validation rules Import and export HL7 MIF static models to/from UML – SOA: service identification, analysis, design, and realization OMG SoaML: modeling SOA in UML – Generation of Java, XSD, WSDL, and other implementations

*** Draft *** OHT UML Modeling Tools (HL7 Extensions) UML profiles for extended HL7 metadata Modeling tool UI enhancements for clinical analysts Terminology constraints on attribute values Modeling extensions work in open source or commercial UML tools Import/export information models from/to HL7 MIF format Validate UML model as HL7 RIM restriction Transform UML model for XSD design and generate schemas

*** Draft *** UML Profile for HL7 Development (model elements)

*** Draft *** UML Profile for HL7 Development (vocab constraints)

*** Draft *** As we have seen, OHT VA/IBM tooling can addresses model representation issues, but key issues remain HL7 characteristicConsequences for requirements realisationAddressed by VA/IBM tooling HL7 modelling approach Basic information modelling very complex due to small set of foundational classes; modelling of entities existing over time difficult; no separation of process-like acts and secondary acts (documentation), counterintuitive modelling of roles Not addressed HL7 constraining/cloni ng approach Barrier to usage of MOF-derived languages if lineages between models and within- model specialisations are to be represented in computable form within the MOF family of languages Usage of EMF impaired due to cloning approach Vertical lineage issue not addressed Cloning issue not addressed HL7 model hierarchy Composed model requirement cannot be metNot addressed HL7 publishingHL7 tooling for publishing relies on MIFNot addressed Remaining issues

*** Draft *** Contents  HL7 requirements and existing solution  Alternative approach: VA/IBM OHT UML tooling  Project mission proposal

*** Draft *** We propose a mission statement to guide this project The mission of this project is to  enumerate the requirements that are addressed by the MIF and the current HL7 tooling  capture upcoming stakeholder requirements  Identify achievements and potential limits and gaps of current solution  identify existing alternative solutions and their gaps  make a recommendation how to move to a higher level of requirements realisation