13. Flows: Flow Definition Example.sysml

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TRAIL: The SysML-v2-Pilot-Implementation GitHub samples in Cameo by Webel

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This View (diagram) deliberately exposes some of the underlying SysMLv2 machinery. You don't usually have to show all of this in your own diagrams!

Click on the image to view it full size

Note that in this sample the ports of tankAssy and eng are NOT redefined to provide "clean" end targets (the flow's payload transfer is between directed features of the inherited ^fuelTankPort and ^engineFuelPort ports). Compare with:

12. Binding Connectors: Binding Connectors Example-1.sysml

For a wider discussion visit:

SysML2.0: Webel: Suggest the spec needs to clarify through more examples whether binding to a parameter or port (or a directed feature of such) that has NOT been redefined in the binding connector context (is just inherited) is valid [it is]

Note also that the Elaborated (aka "exploded") view of the :FuelFlow indicates the ends as being ports. The interpretation is that the flow connects the ports (indicated as end ports in its flow definition) with the payload transfer (specified by the flow usage declaration) being between the directed features out fuelSupply and in fuelSupply of the ports (via the flow, which receives the payload then delivers the payload).

SysML2.0: 'A flow usage is declared as a streaming flow using the kind keyword flow. A flow declaration then includes a specification of not only the source and target related features of the flow, but, more specifically, the output feature of the source from which the flow receives its payload ... and the input feature of the target ... This is done by giving a feature chain with at least two features, the last of which identifies the output or input feature, with the preceding part of the chain identifying the source or target of the flow.'

The right side of the diagram also shows some way you can expose the (otherwise not displayed) directed features (owned by the ends) that participate in the payload transfer. You can even show the ports as full feature symbols using drag n' drop then show their directed features as full feature symbols if you wish.

Visit also: SysMLv2: Cameo: TIP: Displays of flow connections (including proxy notation) do not always clearly display the directed features of the ends that participate in the payload exchange. But there are multiple ways of still displaying those directed features.

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13. Flows: Flow Usage Example.sysml

Notes

[ISSUE, PROPOSAL]{PROPOSED} SysML2.0: Webel: Suggest the spec needs to clarify through more examples whether binding to a parameter or port (or a directed feature of such) that has NOT been redefined in the binding connector context (is just inherited) is valid [it is]

[DISPLAY, MODELLING, TIP, TOOL]{RECOMMENDED} Webel Best Practice: SysMLv2: Cameo: TIP: Prefer show EITHER a specialization relationship from a symbol OR show the specialization in the symbol header using Display Styles -> Show Specialization. Prefer NOT show both modes in one View.

[MODELLING, OPTION]{OPTION} SysMLv2: Webel: Redefining a parameter or port (or a directed feature of such) in a binding connector's context provides a "clean" binding target (as opposed to binding to an inherited feature). BUT it's not always necessary (confirmed by SysMLv2 samples)

[ASSERTION, MODELLING]{INFORMATIVE} SysMLv2: It is permissible to use a flow between compatible directed features of ports without an interface

[ISSUE, PROPOSAL]{PROPOSED} SysML2.0: Webel: Suggest it needs to be clarified whether a regular connection (that is not an interface and is not a flow) may be used between ports.

[ASSERTION, MODELLING]{INFORMATIVE} SysMLv2: It is permissible to use a flow between compatible directed features of port usages without redefining inherited port usages (to create "clean" end targets) in the connection context

[DISPLAY, MODELLING, TIP]{INFORMATIVE} SysMLv2: Cameo: TIP: Displays of flow connections (including proxy notation) do not always clearly display the directed features of the ends that participate in the payload exchange. But there are multiple ways of still displaying those directed features.

[DISPLAY, FEATURE, MODELLING, TIP]{INFORMATIVE} SysMLv2: Cameo: TIP: Use the Elaborate smart manipulator (little magnifying glass icon) on the symbol of any kind of connector (basic connector, flow, interface etc.) to show an "exploded" view of the connection usage.