Introduction to HL7 Charlie McCay

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 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, 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