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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
