representations and models: sysml and beyond david long vitech corporation dlong@vitechcorp.com sedc...

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Representations and Models: SysML and Beyond

David LongVitech Corporation

dlong@vitechcorp.com

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In the beginning, a basic set of views…

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Followed by evolution…

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And insights and influences from UML…

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Next the introduction of frameworks…

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And the SysML revolution!

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Complex Problems, Diverse Groups, and Clear Needs

Analysis, presentation,and argumentation

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What Is A View?

MODEL

VIEW

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Transitioning to an Integrated Toolbox of Fit-for-Purpose Views

Reprinted from DoDAF 2.0

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Criteria for Diagram Choice

• Who is your audience?• What do they want/need to see?• What do you want/need to tell them?

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VIEWS DEPICT BEHAVIOR

Make Information Request

Accept & Format Request Get Product from Inventory Provide Product to Customer

Accept Product

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An Integrated Picture ofBehavioral Views

What about• audience?• level of

detail?

Concepts reflected

CompositionControl / Structure

TriggeringData FlowAllocation

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Behavioral Views

DoDAF OV-1

Level of Detail: LowAudience: GeneralContent: General context often with lightweight composition, triggering, and allocationUse: High-level contextual introduction to describe operational boundaries and align system vision

FFBD

Level of Detail: LowAudience: General, excluding software engineersContent: Specification of flow of controlUse: Initial capture of threads and integrated behavior when focusing purely on control aspects

Sequence Diagram

Level of Detail: MediumAudience: GeneralContent: Specification of sequence (but not control), allocation, and triggeringUse: Initial capture of threads when focusing purely on triggering aspects; communication with software engineers

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Behavioral Views, cont.

N2 Diagram

Level of Detail: LowAudience: GeneralContent: Data flow with possible inclusion of allocationUse: Focused understanding of data flow and implied interfaces; clustering analysis

IDEF0 Diagram

Level of Detail: HighAudience: Traditional SEs and process engineersContent: Data flow, triggering, and allocationUse: Analysis of data flow with diagnostics of inconsistencies across behavioral decomposition

State Transition Diagram

Level of Detail: MediumAudience: System and software engineersContent: System states and the corresponding transitionsUse: Insight into the system by taking an orthogonal look at behavior

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Behavioral Views, cont.

Enhanced FFBD

Level of Detail: HighAudience: Not software engineers or SysML zealotsContent: Composition, triggering, resourcing, and allocationUse: Full specification of system behavior; best at higher levels of decomposition (level 0, level 1, …) when dealing with broader audiences

Activity Diagram

Level of Detail: HighestAudience: System and software engineersContent: Composition, triggering, and allocationUse: Full specification of system behavior; best at lower levels of decomposition (design view)

Simulation Timeline

Level of Detail: MediumAudience: GeneralContent: True performance aspects of specified behaviorUse: Debugging system logic; analysis of performance characteristics

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VIEWS DEPICT COMPONENTS

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An Integrated Picture of Physical Views

PHYSICAL CHARACTERISTICS SPECTRUMMore compositionLess connectivity

Less compositionMore connectivity

Hierarchy

Block DefinitionInternal

Block

Level 0

Level N

Physical N2

Interface Block

Physical Block

Concepts

CompositionConnectionsInheritance

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Physical Views

DoDAF SV-1

Level of Detail: MediumAudience: GeneralContent: General context with lightweight composition and connectivity (logical and physical)Use: High-level contextual introduction to describe system boundaries and align system vision

Physical Hierarchy

Level of Detail: LowAudience: GeneralContent: Multi-level specification of system compositionUse: In-depth hierarchical presentation of parts list

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Physical Views, cont.

Block Definition Diagram (Classification)

Level of Detail: HighAudience: System and software engineers Content: System inheritance modelUse: Detailed representation of any system inheritance and corresponding characteristics; software class diagram

Level of Detail: HighAudience: System/software engineers and subject matter experts (SMEs)Content: Physical composition often including block roles and characteristicsUse: Detailed, multi-level design representation of system composition and corresponding physical characteristicsBlock Definition Diagram

(Structure)

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Physical Views, cont.

Physical N2 Diagram

Level of Detail: LowAudience: GeneralContent: Single-level composition with corresponding logical (interface) or physical (link) connectionsUse: High-level identification of connections; clustering analysis

Internal Block Diagram

Level of Detail: HighAudience: System/software engineers and SMEsContent: Specification of logical or physical connectivity often with ports, directionality, and corresponding data flowsUse: Specification of logical or physical connections

Interface Block and Physical Block Diagrams

Level of Detail: MediumAudience: Not software engineers or SysML zealotsContent: Composition with logical or physical connectivityUse: Specification of logical or physical connections; boundary definition; insight into external connections

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VIEWS DEPICT REQUIREMENTS

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Requirement ViewsLevel of Detail: MediumAudience: System/software engineers Content: Names, relationships, and descriptionsUse: Limited use (a toy representation); context for limited set of requirements

Requirements Diagram

Hierarchy Diagram

Level of Detail: LowAudience: GeneralContent: Names and relationshipsUse: Multi-level decomposition and traceability of requirements

Tables

Level of Detail: HighAudience: GeneralContent: Requirement properties and relationshipsUse: Requirement lists; traceability matrices; verification matrices

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A Few Additional Representations

Parametric Diagram

Level of Detail: HighAudience: Systems engineers and SMEsContent: System parameter definitionUse: Mathematical specification of key system parameters

Use Case Diagram

Level of Detail: LowAudience: GeneralContent: Use cases and corresponding actors (components)Use: High-level tool to elicit requirements; bridge from requirements to system threads

Spider Diagram

Level of Detail: LowAudience: GeneralContent: Object names and interrelationshipsUse: Contextual view of objects of interest with no implied meaning

Dashboards

Level of Detail: LowAudience: GeneralContent: Fusion contentUse: Single page focused illustration; often measurement / management

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Geospatial Library

pbd Geospatial Library

C.3 Customer Certification

Authority

C.1 Customers

C.2 Collectors

SYS.1.2 Workstation SYS.1.1 Command Center

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GL Internal Link

Customers Geospatial Library

seq Thread 1- Product in Inventory

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The Trap to Avoid

Disjoint fit-for-purpose views can wreck our project on the

rocky shores

Diagrams must be representational tools from the model, not a substitute for a model