Webel: SysML: SE: «blackbox»: The custom Stereotype keyword «scenario» indicates a Behavior (Interaction as Sequence Diagram or Activity) that Refines a top-level UseCase within the 'problem' zone.
The Webel recipe for pragramatic SE with SysML adopts the MagicDraw/Cameo tool friendly approach of using a SystemContext as 'subject' of top-level UseCases (although using a System as 'subject' can also be used).
The use case diagram describes the usage of a system (subject) by its actors (environment) to achieve a goal, that is realized by the subject providing a set of services to selected actors. Source OMG Systems Modeling Language (SysML) 1.7beta1
Actors represent classifier roles that are external to the system that may correspond to users, systems, and or other environmental entities. Source OMG Systems Modeling Language (SysML) 1.7beta1
An Actor specifies a role played by a user or any other system that interacts with the subject. Source Unified Modeling Language 2.5.1
Webel: SysMLv1: Overview of annotated Diagram Slides and Note pages related to UseCases and their combination with a System (of interest), SystemContext, and drill-down to scenario Sequence Diagrams (Interactions) and Activity Diagrams.
SysMLv1: A common misunderstanding: 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', and it does not imply ownership!
SysMLv1: "Should" the 'subject' of a top-level UseCase be a System or (a particular) SystemContext? Answer: Which one would you like to be correct!? [WITH EXTERNAL LINKS]
SysMLv1: MagicDraw/Cameo: Having a SystemContext as the 'subject' of each main UseCase plays nicely with the feature for automated creation of usage-level allocation swimlanes in SysML Activity Diagrams for part properties. But it's not the only way.
SysMLv1: MagicDraw/Cameo: Synchronising ItemFlows on Connectors with ObjectFlows in Activities using the Item Flow Manager. Nice!
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.
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’.
MagicDraw/Cameo: You can easily create your own extensions of Block to act as subjects of UseCases. The tool knows how to handle the rectangular ‘subject’ notation on Use Case Diagrams
GOTCHA: UML Component «subsystem» vs non-normative SysML «subsystem» Gallery Tutorial TRAIL: Webel's ultimate guide to Systems Modeling Language (v1) with MagicDraw/Cameo Section 14:01: UseCases in SysML Slide kind hybrid diagram UML Profile Diagram
Package, Model, or SysML Block as UseCase owner Gallery Tutorial TRAIL: Webel's ultimate guide to Systems Modeling Language (v1) with MagicDraw/Cameo Section 14:01: UseCases in SysML Slide kind UML Profile Diagram
UseCases - UML subject vs SysML Block This content has been marked as discussing an ADVANCED topic! Gallery Tutorial TRAIL: Webel's ultimate guide to Systems Modeling Language (v1) with MagicDraw/Cameo Section 14:01: UseCases in SysML Slide kind UML Profile Diagram
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 ... Source Unified Modeling Language 2.5.1
Two UseCases specifying the same subject cannot be associated as each of them individually describes a complete usage of the subject. Source Unified Modeling Language 2.5.1
UseCases may have associated Actors, which describe how an instance of the Classifier realizing the UseCase and a user playing one of the roles of the Actor interact. Source Unified Modeling Language 2.5.1
It may also be described indirectly through a Collaboration that uses the UseCase and its Actors as the Classifiers that type its parts. Source Unified Modeling Language 2.5.1
The behaviors of a UseCase can be described by a set of Behaviors (through its ownedBehavior relationship), such as Interactions, Activities, and StateMachines, as well as by pre-conditions, post-conditions and natural language text where appropriate. Source Unified Modeling Language 2.5.1
Moreover, the UseCases may also state the requirements the specified subject poses on its environment by defining how the Actors should interact with the subject so that it will be able to perform its services. Source Unified Modeling Language 2.5.1
UseCases can be used both for specification of the (external) requirements on a subject and for the specification of the functionality offered by a subject. Source Unified Modeling Language 2.5.1
It is deemed complete if, after its execution, the subject will be in a state in which no further inputs or actions are expected and the UseCase can be initiated again, or in an error state. Source Unified Modeling Language 2.5.1
Each UseCase specifies a unit of useful functionality that the subject provides to its users (i.e., a specific way of interacting with the subject). This functionality must always be completed for the UseCase to complete. Source Unified Modeling Language 2.5.1
A subject of a UseCase could be a system or any other element that may have behavior, such as a Component or Class. Source Unified Modeling Language 2.5.1
UseCases define the offered Behaviors of the subject without reference to its internal structure. These Behaviors, involving interactions between the Actors and the subject, may result in changes to the state of the subject and communications with its... Source Unified Modeling Language 2.5.1
A UseCase is a kind of BehavioredClassifier that represents a declaration of a set of offered Behaviors. Each UseCase specifies some behavior that a subject can perform in collaboration with one or more Actors. Source Unified Modeling Language 2.5.1
A UseCase may apply to any number of subjects. When a UseCase applies to a subject, it specifies a set of behaviors performed by that subject, which yields an observable result that is of value for Actors or other stakeholders of the subject. Source Unified Modeling Language 2.5.1
In particular, there is scope for confusion between a UseCase appearing visually contained in a boundary rectangle representing a Classifier that is its subject, and appearing visually contained in a compartment of a Classifier that is its owner... Source Unified Modeling Language 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. Source Unified Modeling Language 2.5.1
Note that this notation for the subject classifier differs from the normal Classifier notation – it has no header or compartments. Source Unified Modeling Language 2.5.1
“BlackBox” for the purpose of this example, refers to how the subject system (HybridSUV block) interacts only with outside elements, without revealing any interior detail. Source OMG Systems Modeling Language (SysML) 1.6
Visual containment of the symbol for a UseCase in the rectangular symbol for a subject Classifier does NOT imply ownership! Packaging (ownership) of UseCases is separate from use within subjects, and a single UseCase may be used in more than one subject.
Figure D.6 - Establishing Operational Use Cases for Drive the Vehicle Gallery Tutorial TRAIL: The SysML-1.6 Hybrid SUV sample and specification diagrams in MagicDraw/Cameo (with annotations) [UNDERGOING UPDATE to SysML1.7] Section Section: SysML-1.6: HSUV sample Slide kind SysML UseCase Diagram
In MagicDraw/Cameo the name and any stereotype keywords of a Classifier subject of a UseCase may be shown in the top-middle (not just top-left)
In cases where the metaclass of a subject is ambiguous, the keyword . corresponding to the notation for the metaclass of Classifier (see 9.2.4) shall be shown in guillemets above the name. Source Unified Modeling Language 2.5.1
Where a subject is a Classifier with a standard stereotype, the keyword for the stereotype shall be shown in guillemets above the name of the subject. Source Unified Modeling Language 2.5.1
The same modeled UseCase may be visually depicted as separate ellipses within multiple subject rectangles. Source Unified Modeling Language 2.5.1
A subject for a set of UseCases (sometimes called a system boundary) may be shown as a rectangle with its name in the top-left corner, with the UseCase ellipses visually located inside this rectangle. Source Unified Modeling Language 2.5.1
Figure D.5 - Establishing Top Level Use Cases for the Hybrid SUV Gallery Tutorial TRAIL: The SysML-1.6 Hybrid SUV sample and specification diagrams in MagicDraw/Cameo (with annotations) [UNDERGOING UPDATE to SysML1.7] Section Section: SysML-1.6: HSUV sample Slide kind SysML UseCase Diagram
The use case diagram for “Drive Vehicle” in Figure D.5 depicts the drive vehicle usage of the vehicle system. The subject (HybridSUV) and the actors (Driver, Registered Owner, Maintainer, Insurance Company, DMV) interact to realize the use case. Source OMG Systems Modeling Language (SysML) 1.6
UseCase::subject : Classifier [0..*] ... The subjects to which this UseCase applies. Each subject or its parts realize all the UseCases that apply to it. Source Unified Modeling Language 2.5.1
Webel: SysMLv1/UML: MagicDraw/Cameo: AVOID the the vendor-specific «useCaseModel» stereotype for Model packages, it leads to confusion with the rectangular 'subject' notation
