using "satisfy" between a req and a diagram

[Raphael Faudou]

Hi all,

I have faced several situations where engineers want to relate a requirement with a diagram using a "satisfy" relationship.

I found it strange as a diagram is a view and we create such relation between model elements and I have never found such relation in any model so far.

But after some thinking, the diagram could be used as a group of elements with the meaning that the "satisfy" relationship is implicitly defined between the requirement and all the model elements referenced in the diagram.

What do you think? 

From the pure specification point of view, the spec says that "satisfy" shall be done between a requirement and a model element. 

Is the diagram a model element?

if yes, it would mean it is an acceptable relation.

Thanks for any feedback on that

Raphael

[gashu...@gmail.com]

Hi Raphael,

My take on this concern, possibly flawed.  The SysML v1.7 spec states " The frame is a rectangle that is required for SysML diagrams (Note: the frame is optional in UML). The frame shall designate a model element that is the default namespace for the model elements enclosed in the frame. "  Would not the model element represented by the frame be the "client of the «satisfy» relationship" to the requirement?  The purpose then of the particular diagram must be to document the elements involved in satisfying the requirement.  Just my thoughts.  BTW, the spec also states that "A qualified name for the model element within the frame shall be provided if it is not contained within default namespace associated with the frame. "  If the diagram documents a 'Service' the elements composing the service need not be in the service's namespace.  Yes?

Regards,

Geoff

[Pascal Roques]

I have always thought that a diagram is NOT a model element...

Pascal

[Stephan Roth]

Hi all,

a UML/SysML diagram IS NOT a model element. There is no «metaclass» Diagram in the UML metamodel, which means that there can be no such thing in SysML either.

Since, according to the SysML specification, a «satisfy» relationship can only be modeled between a SysML requirement and another model element, it is not possible to use a diagram in this relationship.

However, it is possible, for example, to model a «satisfy» relationship between requirements and model elements that provides a context for a certain diagram. For example:

• Activity -> The process flow is depicted in an activity diagram.
• State Machine -> The states and state transitions are depicted in the associated state diagram.
• Block -> The internal structure of the block is depicted in an internal block diagram.
• ...

Hope that helps.

Best regards,

Stephan

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