1. XML in HL7 Version 3 Messaging
Using XML in HL7 Version 3
9/14/98
XML in HL7 Version 3 Messaging
Wes Rishel
Vice-chair, Technical Steering Committee
©1998 by HL7 & Wes Rishel

2. Using XML in HL7 Version 3
The Change Paradox
9/14/98
It is change, continuing change, inevitable change, that is the dominant factor in society today. No sensible decision can be made any longer without taking into account not only the world as it is, but the world as it will be
Isaac Asimov (1920–92)
Most of us are about as eager to be changed as we were to be born, and go through our changes in a similar state of shock.
James Baldwin (1924–87)
It is change, continuing change, inevitable change, that is the dominant factor in society today. No sensible decision can be made any longer without taking into account not only the world as it is, but the world as it will be
Isaac Asimov (1920–92)
Most of us are about as eager to be changed as we were to be born, and go through our changes in a similar state of shock.
James Baldwin (1924–87)
1/10/2019
©1998 by HL7 & Wes Rishel
©1998 by HL7 & Wes Rishel

3. Interfaces installed much more quickly
Using XML in HL7 Version 3
The Gain (V3 Benefits)
9/14/98
Interfaces installed much more quickly
reduce sight-specific negotiations
greatly reduce custom programming
asymptote is “plug and play”
Conformance claims; support for conformance testing
Functional adaptation to the changing healthcare system
Goals
interfaces installed more quickly
reduced discovery of misunderstandings during testing or in production
reduced time renegotiating communications portion of interface
“harmonization” with other healthcare standards
functional partition
transliterability
interoperation
1/10/2019
©1998 by HL7 & Wes Rishel
©1998 by HL7 & Wes Rishel

4. Improved clarity and correctness of specification
Using XML in HL7 Version 3
Other Benefits
9/14/98
Improved clarity and correctness of specification
Appropriate to newer communications paradigms
New paradigms: object oriented analysis, distributed objects.
1/10/2019
©1998 by HL7 & Wes Rishel
©1998 by HL7 & Wes Rishel

5. The Pain? Changes to the interface software
subtle, but substantial
segment groups
subsubsubcomponents
recursive types
Functional changes to systems
more precise specifications
requirement to use data that is received
Retraining
1/10/2019
©1998 by HL7 & Wes Rishel

6. Is the Pain worth the Gain?
Using XML in HL7 Version 3
Is the Pain worth the Gain?
9/14/98
Retooling of character-stream based interface software for recursive syntax
Or, adaptation of object-based approaches, with corresponding benefits
Analyst time to interpret 2.3 transactions and configure interface engines for 3.0
1/10/2019
©1998 by HL7 & Wes Rishel
©1998 by HL7 & Wes Rishel

7. Other Observations on Change
Change is inevitable ...
… inevitably slower than anticipated
Change for marginal benefit gets overrun by newer change
Change begets change
1/10/2019
©1998 by HL7 & Wes Rishel

8. The Revolution, um, Evolution of XML
eXtended Markup Language
Fundamental economic driver is an evolutionary change to the World Wide Web
content-based searching and presentation
management of documents in pieces
indirect links
etc.
Compatible upgrade to HTML
1/10/2019
©1998 by HL7 & Wes Rishel

9. XML Benefits Will Beget Other Changes
Document markup: SGML changes its costume and gets “discovered”
Self-documenting data files
almost self-parsing
The begetting happens through
tools,
people,
and hoopla (i.e. the attention of the marketing department)
1/10/2019
©1998 by HL7 & Wes Rishel

10. XML and Version 3 The syntax handles recursion Parsers are “free”
Self-documenting data files
XML-related tools
viewing
testing
conversion
Availability of trained personnel
reflected Hoopla
1/10/2019
©1998 by HL7 & Wes Rishel

11. Describing an HL7 Message Format
1/10/2019
©1998 by HL7 & Wes Rishel

12. Technology Layering in V3 Messaging
1/10/2019
©1998 by HL7 & Wes Rishel

13. The Gotchas Not a patch to an existing parser
Access to “free” parsers on legacy operating systems
Message sizes substantially larger
XML does not allow us to specify all the characteristics of a “valid” HL7 message.
1/10/2019
©1998 by HL7 & Wes Rishel

14. The Plan Prototype Prototype goals: demo at HIMSS in HL7 booth
multiple systems
mixed version 2 and v3/XML
interface engine
Prototype goals:
evaluate methodology
evaluate parsing difficulty/message size
HOOPLA
1/10/2019
©1998 by HL7 & Wes Rishel

15. Implementing Version 3 as Change
Using XML in HL7 Version 3
Implementing Version 3 as Change
9/14/98
End user benefits need to be proven
Some will derive from RIM improvements currently underway
Some will derive from being enabled by new enabling technologies
We are now entering the fray!
1/10/2019
©1998 by HL7 & Wes Rishel
©1998 by HL7 & Wes Rishel

16. Dr. Asimov Revisited
“No sensible decision can be made any longer without taking into account not only the world as it is, but the world as it will be ”
Design decisions require cautious optimism about change.
Five years from now, if V3 does not use XML, people will, at best, be amused by our quaint eccentric ways.
1/10/2019
©1998 by HL7 & Wes Rishel