1. HL7 - Health Service Reference Architecture (HL7-HSRA) PSS
Overview
HL7 International Jan 2018 Working Group meeting New Orleans LA

2. HL7 - Health Service Reference Architecture (HL7-HSRA) PSS
Assumption
The HL7 based standards support almost all the possible scenarios of eHealth interoperability.
However, the architectural viewpoint needed to bring these standards together to address Enterprise interoperability is not specifically addressed.
This lack of support increases the design and planning barriers to realizing HL7 based architectures. This can also lead to relevant HL7 standards being omitted from, or misused in, medium and large- scale environments.
The Health Service Reference Architecture (HL7-HSRA) takes into consideration the needs of architects and CIOs to undertake a fully pervasive, sound, balanced and cost effective HL7 Service design for Enterprise interoperability.

3. HL7-HSRA Objectives
Objectives
The main objective of the HL7 Enterprise Reference Service Architecture (HL7-ERSA) is to support the design of medium/large scale eHealth architectures (at enterprise level) based on HL7standards.
Building Enterprise Service architectures requires an understanding of composite solutions that include different services organized in choreographies and/or orchestrations which cover many areas within medium to large-scale organizations.
The intent of the HL7-ERSA is to support the process of architectural design with a map of building blocks and solution patterns based on existing HL7 Standards.

4. HL7-HSRA Audience
Audience
The audience of the HL7-HSRA will be principally focused on architects and CIOs that need to design, plan and evaluate enterprise wide solutions for complex organizations.
However, the project is relevant also for the internal HL7 audience.
The HSRA outcome verify the consistency of HL7 standard and potential area not fully covered or with relevant overlapping.
The Pattern Catalog can also support the mapping among different HL7 based standard for the behavioral aspects (e.g. V2-V3-FHIR)

5. HL7-HSRA Expected outcomes
This project aims to organizes HL7 Service Functional Models, Functional Profiles and Domain Models into:
a formalized Enterprise Service Inventory
an Architectural Patterns Catalog
associated methods for enterprise Service discovery and orchestration
The projections of specific technology/standard service implementations (FHIR, OMG/HL7 Soap services, IHE XD* family) will be discussed

6. HL7- HSRA Service Architecture
The diagram sketches the (draft) HSRA Architecture/Service Inventory
Each service can have tree projection in:
FHIR/REST,
HL7-OMG WS*
and XD* profile

7. HL7- HSRA Formalized Enterprise Service Inventory
«A service can be seen as a container for a collection of related functions.»
«A service inventory is an independently standardized and governed collection of complementary services within a boundary that represents an enterprise or a meaningful segment of an enterprise.» (Thomas Erl)
The basic Idea is to organize and reconsider the HL7 service inventory (mainly based on HL7 Service Functional Models)
For each service the main implementable projections (FHIR, SOAP, XD* …) wil be individuated
Must be underlined that an, implicit, HL7 Services Inventory exist, but it's dispersed in several documents and specification => low usability.

8. HL7-ERSA Architectural Patterns Catalog
A service, in the real world, do not live alone, it’s combined in architectures (of cooperating components that expose services).
In a Reference Architecture, we should individuates and describes Architectural Patterns as general, reusable solutions to real world occurring problems in software architectures
The inventory previously sketched in the Catalog will be combined in patterns that describe solution at business problem
As a basis for pattern definition the OMG Standard: Structured Patterns Metamodel (SPMS) should be, probably, used.

9. Patterns general structure
The diagram is a simplified fragment of SPMS.
It’s useful to understand the Patterns basic structure and how it’s related with the Inventory

10. Example: Pattern model Example
The appropriate modeling standard will be discussed (e.g. Sequence diagram, SoaML, BPMN2, CMMN)

11. HL7-HSRA associated methods for enterprise Service discovery and orchestration
Methods for discoverability and orchestration are, obviously, critical aspects for medium/large scale architectures.
HL7-HSRA, per-se, will support these aspects at conceptual and design levels. Patterns Catalog describe useful choreographies of services and the Service Inventory improve discoverability.
However this is not enough: at patterns instance (implementation) specific methods and strategies should be used level will be discussed/defined in the project.
E.g. WS* and REST requires slightly different approach, technologies and standards for orchestration and service discoverability.

12. HL7- HSRA
… now dicussions and Work