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Introduction to HL7. Charlie McCay Charlie@RamseySystems.co.uk. Charlie McCay. Interest in Clear and Testable specifications Co-Chair HL7 XML Special Interest Group Chair HL7UK Technical Committee XML input to these specifications: RACPC+PROFESS – CEN 13606 data-sets
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Introduction to HL7 Charlie McCay Charlie@RamseySystems.co.uk
Charlie McCay • Interest in Clear and Testable specifications • Co-Chair HL7 XML Special Interest Group • Chair HL7UK Technical Committee • XML input to these specifications: • RACPC+PROFESS – CEN 13606 data-sets • GP2GP – early adopter for HL7V3 • ETP – Electronic Transfer of Prescriptions Pilot • DMSP Clinical pathways (HL7v3)
How HL7 works • HL7.org and HL7UK… • Products… • Organisation… • Meetings… • Ballots…
HL7.org and HL7UK • Membership organisations • Both aim to provide standards that support Clinical Information System Interoperability • HL7UK does this in a UK context
Products • Specifications • V2, V3, CDA, Arden, CCOW, … • Informative, Normative or Reference • Methods for developing specifications • MDF, HDF, …
Organisation • ANSI, ISO, CEN • TCs, SIGs and others • Technical Committees • Special Interest Groups • HL7.org, and the affiliates
HL7.org Meetings • Working Group Meetings • Three meetings a year, 400 attendees • Committee work and tutorials • Harmonisation • Three times a year, 20 attendees • Conference calls • Mailing lists
HL7UK meetings • 6 technical meetings a year, 20-30 attendees • Networking • Reporting on UK HL7 projects • Planning UK activity in HL7.org • detailed review • UK conference • HC200x Stand and demonstrations
Ballots • Central and Affiliate • Committee and Membership • Joining ballot pools, and meaning of votes • Resolution of negatives
Semantics and Technology • “Semantics” is the definition of the data items that are permitted in the message • “Technology” is what is used to transmit that meaning between systems • Hl7v3 is semantics, XML is technology
Skills Reuse • XML used for more than just EDI • Component interfaces • User interface • Printed Document formatting • Temporary and persistent Data storage • Semantics are not just used in interfaces • Reporting engines • System architecture • Requirements gathering
Training and Skills • EDI needs experienced developers • XML skills can be developed elsewhere • Parser writing • Not need widely in Clinical applications • Error prone • EDI can become a trap for good developers
Validation at Source • Schemas, DTDs, and black boxes • Keep your own dirty laundry • Avoid doing free testing for other suppliers • Identify who is responsible for errors • Machine readable specifications • Taken further in V3
Are the Schemas normative • Do I have to use the Schema?… • What is normative is the definition of the set of valid instances • DTD / Schema used for: • Description • Validation • Validation takes time • Diagnostic and runtime validation
Is Schema validation enough? • No – Rules the schema does not check • Co-occurrence constraints • Contingencies on facts beyond the message • Orchestration of the messages • No – Schema validators get better
Tools • Visio Tools • Schema generator • Message Viewer – xClinView • Message Documentation Editor • Schema processors, rsXMLtest • XML IDE -- XML Spy