Visual Modeling – HL7 Challenges, Benefits, and Applications (Is a Picture Worth 1000 Words?) Charlie Mead, MD, MSc Director, Healthcare Information Architecture

Visual Modeling –

HL7 Challenges, Benefits,and Applications

(Is a Picture Worth 1000 Words?)

Charlie Mead, MD, MSc

Director, Healthcare Information ArchitectureOracle Healthcare

([email protected])

Director, HL7 Board of DirectorsCo-Chair, Patient Care Technical Committee

Co-Chair, Personnel Management Technical Committee

Slide - 2HL7 UK December 12, 2003

This is a model…

• Referral• Transportation• Supply• Procedure• Consent• Observation• Medication• Act complex• Financial act

• Organization• Place• Person• Living Subject• Material• Health Chart

• Patient• Member• Guardian• Healthcare facility• Practitioner• Location• Specimen

Entity

1

0..*

1

0..*

Role Link

0..*

1,1Role

1

0..*

1

0..*

ActRelationship

0..*

1

0..*

1Participation Act

• Subject• Beneficiary• Author• Consultant• Referrer• Informant• Witness

• Fulfills• Component• Supported by• Documents• Replaces

• Direct Authority• Indirect Authority• Part of• Replaces


…as is this…

RIMBig.gif


…and so is this!


The Problem vs The Solution The Problem

– Implementation-independent– Discovered by ‘analysis’ activities– One Problem Many Solutions

The Solution

– Implementation-specific– Formulated by ‘design’ activities– A set of compromises/constraints imposed in the context of a specific

Problem Often only addresses a portion of the Problem

Understand the Problem before attempting to design the Solution

– This is NOT an endorsement of Waterfall Iterative/Incremental development is best for complex problems

– ‘Understand the Problem’ means ‘Understand the essence of the Problem’ Separate key structural and behavioral aspects of the problem


What is a Model? A representation of “what’s important”

– Emphasizes concepts and relationships Attributes of concepts are concepts!

– Hides unnecessary details ‘Unnecessary’ is defined contextually

– Focuses on elucidating structure and/or function Syntax Semantics Collaborations/interactions

A ‘’human-friendly picture” of complexity– Encourages ‘encapsulation’– Supports ‘extensibility’– Facilitates ‘layering’– Enables cognitive ‘chunking’

7 +- 2 ‘concepts in hand’


What is a Model

“Something that accurately resembles something else; a thing that represents on a small scale the structure or qualities of something greater.” [OED 2002]

“A model captures a view of a physical system. It is an abstraction of the physical system, with a certain purpose. This purpose determines what is to be included in the model and what is irrelevant. Thus the model completely describes those aspects of the physical system that are relevant to the purpose of the model, at the appropriate level of detail.” [UML 2001]

Examples of models– Business Process model– UML Diagrams (Class, State, Activity, Sequence, etc.)– ER Diagram– Java code


What is a Model?

A model is most correctly defined as a set of views (often expressed in the form of diagrams) of a particular system-of-interest (SOI)

– Structural views– Behavioral/dynamic views

A model (or a given view) is constructed using a modeling language


What is a Modeling Language?

A language (syntax/grammar and semantics) for building models

An expression a Problem (or Solution) using a ML….– Facilitates the visualization of complexity– Supports the specification of architectural details– Enables the documentation of decisions made about the

system, its scope, etc.– Guides the construction of instances of the system

represented by the model


What is a visual Model?

A model is expressed using a (primarily) visual modeling language

– Based on graphic icons with defined semantics– Icons combined based on underlying

syntax/grammar– Visual models have traditionally been considered

‘documentation/snapshots’– Visual models are increasingly becoming

‘computable’ UML 2.0’s Model-Driven Architecture


Why model?

Models help define the scope of a problem and/or solution

Models represent an important vehicle for reaching consensus about the architecture (structure and function) of a Problem and/or a Solution

A given model of a Problem can profoundly affect the nature of the Solutions proposed and developed to solve the Problem

– Seeing the Problem modeled Imagining/Considering the possible Solutions


Why model?

Models are (can be)….– Precise– Unambiguous– Complete– Verifiable between Problem and Solution Domain – Executable

‘There are no right / correct models. Some models are more helpful than others.’

Models (i.e. the collected set of views that comprise a model) help narrow and/or bridge the inherent semantic gap that invariably exists between the various levels of the Problem and its respective Solutions


Understanding the Problem:The Communications Pyramid

Express the Problem in ‘domain-speak’ rather than ‘solution-speak’– GLOSSARY, GLOSSARY, GLOSSARY

Express the Problem using multiple nearly independent views– A set of ‘layered views’

Structure vs Behavior

Express structure and behavior visually/graphically (rather than textually) whenever possible

– Core concepts and their relationships UML Class Diagram

– Core responsibilities, process flows, and interactions UML Activity Diagram

UML Use Case Diagram UML Sequence/Collaboration Digram UML State Diagram


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The Communication Pyramid

Communication

Free-text Documents

Structured Documents

ad hoc Drawings

Non-standard Graphics

Discussions

Standardized Models (UML)

Probl

em

Probl

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Space

Space

Solution

Solution

Space

SpaceIm

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Inde

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entation-Specific


The Unified Modeling Language (UML) UML is a modeling language

– (mostly) Visual Syntax Semantics Object Constraint Language (the ‘non-visual’ part)

– Extensible Tags and Profiles

UML is NOT– A modeling process– A modeling tool

Learning UML: Suzuki’s ‘language learning levels– Exposure, Imitation, Usage, Understanding, Composition


The UML is… A well-defined (mostly) visual language for describing the structure and/or function of complex

systems.– A language supporting well-formed models

The UML is a language that facilitates….– ….visualizing complexity– ….specifying relationships and interactions– ….guiding the construction of the modeled system– ….documenting the decisions made about the modeled system

The de facto modeling language standard managed, maintained, and evolved by the Object Management Group (omg.org)

– 10-15 years in develop– Convergence of multiple perspectives and agendas


Primary Design Goals of the UML

Provide users with a ready-to-use, expressive visual modeling language to develop and exchange meaningful models

Furnish extensibility and specialization mechanisms to extend the core concepts

– e.g. HL7 Profile

Provide a formal basis for understanding the modeling language

Encourage the growth of the object-orient tools market

Support higher-level development concepts such as components, collaborations, frameworks and patterns

Integrate best practices in complex system development


UML Building Blocks

Things– Classes– Objects– Activities

Relationships– Syntactic– Semantic

Diagrams– Static Structure– Dynamic Behavior


UML Model Views

Static Diagrams– Class Diagram– Object Diagram– Implementation Diagrams

Deployment Diagram Component Diagram

Behavioral Diagrams– Use Case Diagram– Activity Diagram– State-chart Diagram– Activity Diagram– Interaction Diagrams

Sequence Diagram Collaboration Diagram


The RIM and Modeling

RIMBig.gif

PRPA_NA000002.gif

QUQI_NA000001.gif


DMIMs, RMIMs and Modeling

PM DMIM 03-nov-12 visio5.vsd

RMIM1.gif RMIM3.gif RMIM5.gif RMIM6.gif RMIMSimple.gif

‘Increasing constraints on the RIM’– Class– Attributes– Relationships– Multiplicities– Data Types– Vocabulary


The HL7 Development Framework (HDF): What Models Should We Build?

The HDF recognizes the importance of separating analysis activities from design activities

– Use ‘domain-friendly’ terms to build ‘analysis’ views– ‘Map’ analysis views to design views

A given concept or relationship in the Domain Analysis model may map to a RIM

Class Attribute Vocabulary


Requirements Gathering and Analysis

RequirementsGathering and

Analysis

RequirementsSpecification

Project Charter

Prepare storyboards that elaborate upon the project scope statement.

Build one or more UML Activity Diagram(s) detailing the behavioral component of the requirements (including Storyboard materials)

Build a Domain Analysis Model (UML Class Diagram) to define the structural aspects of the requirements.

Build a domain-specific Glossary for use in down-stream RIM mapping.

Prepare UML Use Case and derived Collaboration and/or Sequence diagrams to depict the interaction requirements.


Requirements Normalization and Harmonization

RequirementsNormalization

andHarnonization

RequirementsSpecification

ReferenceModel

Map models from the Requirements Specification to Reference Models (e.g. RIM, DMIMs, RMIMs).

Revise models in the Requirements Specification based upon discoveries made during the mapping process.

Document proposed changes to Reference Models to accommodate unmapped requirements.

Follow the reference model harmonization process to adjudicate the proposed changes to Reference Models.

Revise the Requirements Specification as needed and its mapping to the Reference Models.


HDF Requirements and Analysis:A ‘minimal set of UML diagrams’

needed to express domain knowledge

Class Diagram Static Structure

Activity Diagram Dynamic Behavior– Grounded in ‘real-world’ storyboards

Glossary– NOT an UML diagram– NOT fun (or easy) to develop– ESSENTIAL FOR SUCCESS


HL7 Modeling Challenges

HL7 has assembled a considerable amount of process and number of artifacts without too much concern to UML et al

– Inhibits organization’s (person-to-person) communication with non-healthcare organizations, etc.

HL7 is not (in general) interested in software systems– UML is primarily designed to facilitate OO software development

Only a partially true statement

HL7 does not have extensive internal modeling/UML expertise– How should membership’s responsibilities be partitioned/best utilized?

Model building vs Model reviewing Level of abstraction of models based on perspective


HL7 Modeling Benefits

Leverage the increasing presence of a de facto standard (UML) in terms of

– Tool support– Interchange standards (e.g. XMI)– Mappings to other technologies (UML XML)– Increasing knowledge base among non-healthcare

professionals Decreasing the semantic impedance between the

Problem Domain and the Solution Domain


HL7 Modeling Applications:Past, Present, Future

Past:– RIM/DMIMs/RMIMs:

Loose compliance with UML in both RIM and DMIM/RMIM Non-standard icons

RMIM icons (based on Peter Coad ‘UML in Color’) Non-standard adornments

Inconsistent treatment of association names vs role names Non-standard structures

Clones Hybrid object/class diagrams HL7 Interactions vs UML Interaction diagrams Use Cases vs Storyboards

– Other HL7 specifications not rigorously represented in UML



Present:– HDF is committed to bringing HL7 into ‘maximum possible UML

compliance’ HL7 is registering a UML Profile with OMG

Applies UML’s extensibility constructs Addresses many of the previously ‘non-standard’ HL7 concepts

HL7 meta model derived from UML meta model HDF is NOT limited to message development

Can (and should) be applied to all HL7 Specifications– Visio diagrams can be made UML compliant

?? Necessary ??

“HL7 will deviate from UML only in those cases where UML is not able to express/support the needed semantics” (HDF)



Future:– Increasing semantics of v3 Conformance Profiles

Interactions, Triggers, Application Roles, Receiver Responsibilities et al

HL7 v3 will need specify certain aspects of system behavior

Aspects that affect semantic interoperability Use Cases in which actors are Application Roles

– UML 2.0 (MDA) offers considerable opportunities– HlL7 artifacts are (increasingly) 100% UML compliant

facilitates tool-independent exchange– Opportunities for HL7 Facilitators etc. to become more

involved with OMG processes


The RIM Backbone

• Referral• Transportation• Supply• Procedure• Consent• Observation• Medication• Act complex• Financial act

• Organization• Place• Person• Living Subject• Material• Health Chart

• Patient• Member• Guardian• Healthcare facility• Practitioner• Location• Specimen

Entity

1

0..*

1

0..*

Role Link

0..*

1,1Role

1

0..*

1

0..*

ActRelationship

0..*

1

0..*

1Participation Act

• Subject• Beneficiary• Author• Consultant• Referrer• Informant• Witness

• Fulfills• Component• Supported by• Documents• Replaces

• Direct Authority• Indirect Authority• Part of• Replaces


References

www.omg.org– The core UML site including UML 2.0

www.ectoset.com– Affordable (<$100) UML modeling tool

www.rational.com– White papers on tools and the use of the UML in

building ‘real-world’ systems
