Implementation FAQ:Migration from version 2

This page contains questions related to the migration of HL7 version 2 to version 3, mostly from a non-technical perspective.

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Questions

Selling point for V3

Question: What is the real value of the reference model in V3 – what is the life of the system –this can be a long time for strategic programs. These need to be future-proofed.

• Two documents from the Marketing Committee's document page that discuss the rationale for using HL7 version 3:
  • Draft HL7 v3 Value Proposition Document
  • Canada Infoway v3 Infosheet

Question: I have a running system using V2, how do I justify moving to V3, especially as V2 just keeps getting better.

• The justification of v3 lies in those areas that v2 doesn't cover (e.g. inter-organizational communications, CDA, clinical genomics).

Recommendations

Don't assume v2 - v3 mapping can be done at the integration layer

If your application already supports HL7 v2: HL7 v2-v3 migration by means of a mapping is problematic. The main problem is not the mapping itself (although HL7 v3 is much more detailed than HL7 v2), but the behaviour of the application. This is mainly a business flow issue. The dynamic behaviour and trigger events in V2 and V3 are sufficiently different, that your application behaviour will need to map on to them differently. If your application has to support both HL7 v3 as well as HL7 v2: create a new communication module for the HL7 v3 messages/documents, and use it in parallel to the HL7 v2 communication module.