SOA: Dynamic Modeling for HL7

1. SOA: Dynamic Modeling for HL7 HSSP Implementation Guides and Best Practices John Koisch, VA July 12th, 2007

2. Goals • Show latest work on HSSP Service Definition and Modeling • Show how this ties into the HL7 Dynamic Modeling evolution • Show why WSDL is not enough ….

3. SOA 4 HL7 • Top Down and Bottom Up Alternative approaches for Service Specification and Creation • Top Down – Very close to the HL7 HDF • Bottom Up – Reuse of existing artifacts, partnerships, designs, etc. • Focuses on usable artifacts (WSDL Creation) and reuse of existing information structures

4. SOA 4 HL7 Example (Slide 1) • Deliverables and their relation to HL7 components

5. SOA 4 HL7 Example (Slide 2) • Service Description

6. SOA 4 HL7 Example (Slide 3) • Interface Identification

7. SOA 4 HL7 Example (Slide 4) • Operation Identification

8. SOA 4 HL7 Example (Slide 5) • Note on Operation Identification:

9. SOA 4 HL7 Example (Slide 6) • Message Content

10. SOA 4 HL7 Example (Slide 7) • Other Topics: • Exception Handling • Acknowledgements • Service Choreographies and Orchestrations • Service Compositions

11. SOA 4 HL7 Example (Slide 8) • Service Creation Methodology • Functional Specification • PIM • PSM

12. SOA 4 HL7 Example (Slide 9) • Functional Specification • Define Requirements • Define Process and Information Capabilities • Id and Name Service Components • Map Requirements to Components • Produce Logical Specification

13. SOA 4 HL7 Example (Slide 10) • Platform Independent Model • Refine Interaction Solution • Refine Component definitions • Define Detailed Dynamic Model • Specify Operations and Messages • Define QoS considerations • Produce PIM Specification

14. SOA 4 HL7 Example (Slide 11) • Define Platform Specific Solution • Define Scope (Constrained Functional Model) • Platform Selection (WSDL, eg) • Produce PSM • Identify Services (/consumers, interfaces, operations, parameters) • Produce Interface Specification • Define Technical Conformance Levels • Documentation

15. SOA 4 HL7 Example (Slide 12) • WSDL Definition • Documentation • Port Type – logical definition of an interface • Operation – From PSM • Input – Input Parameters • Output - Output Parameters • Fault

16. Insidious Problems • HL7 Governance (message level, application roles) vs SOA Governance (interface, contractual) • HL7 HDF – message-oriented, information-focused • Rich content v Skinny content • Information hides behavior • Specificity in Description • Problems for governance, designers, developers • Documentation is always last • WSDL = Web Services = Services = SOA

17. HL7’s Dynamic Model and SOA • Purpose: To reexamine the HL7 HDF and bring into alignment with foundational IT Methodologies • Standard Artifacts • Messaging may be one PSM

18. Overall Conclusions – Similarities and Differences • Mapping between V3 messaging concepts and SOA Service Definitions is not automatic/deterministic. However, the quality/appropriateness of a Service Definition is subjective and there is a reasonable mapping if judgment is used.

19. Similarities and Differences (Cont)

20. HL7 Dynamic Model Alignment with SOA } Common

21. Durable Inter-system Integration for Healthcare • Investigating WS-CDL • Moves the governance model towards interfaces • Moves the location of coordinated behavior into the System of Systems • Still owned by subsystems