SysMLv1: MagicDraw/Cameo: INTRINSIC GOTCHA: Care must be taken with ownership of Activities used as UseCase scenarios vs the ‘subject’ of the UseCase. Make sure you don’t get an Activity ‘context’ mismatch! It's up to you to manage it as intended.

Please note firstly that just because a UseCase symbol appears inside the rectangle of a subject Classifier does not mean that it is owned by that Classifier and can only have that one Classifier as 'subject':

UML-2.5.1: 'UseCases need not be owned by their subject.'

UML-2.5.1: 'A UseCase may be owned either by a Package or by a Classifier. Although the owning Classifier typically represents a subject to which the owned UseCases apply, this is not necessarily the case ...'

UML-2.5.1: 'Note also that the subject rectangle does not imply that the subject classifier owns the contained UseCases, but merely that the UseCases apply to that classifier.'

MagicDraw/Cameo has nice automated handling of the 'subject' of UseCases when moved between Block symbols in Use Case Diagrams. But in the case where a scenario Activity for a Use Case is owned by a Block, caution must be exercised that the intention is the same as the ownership in the model containment browser, otherwise the context of the Activity can get out of sync as shown in the image.

This is not a tool bug or issue, it's a consequence of the flexible approach for organising UseCases in SysML. It's up to you to manage it. Whether you choose to have UseCases owned by blocks at all is a modelling choice, you can instead have them owned by separate Packages, de-coupled from any candidate 'subject' blocks as shown, however then you miss out on this nice tool feature:

SysMLv1: MagicDraw/Cameo: Automated creation of usage-level allocation swimlanes in SysML Activity Diagrams for part properties of a Block. EXAMPLE: A UseCase scenario within a SystemContext as UseCase ‘subject’.

Relates to

SysML/MBSE: Cameo/MagicDraw: MagicGrid® and the MagicGrid® Book of Knowledge: A pragmatic review of some selected aspects by Dr Darren of Webel IT Australia

Webel SE: pragmatic tool-friendly functional analysis: 2-level drill-down from a single Use Case via a «scenario» Activity with allocation to «logical» subsystems first then crossing to the «design» Blocks zone.

Related notes