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Products » objectiF RM » Requirements Engineering » Diagrams » Use Case Diagram

Use Case Diagram

Use case diagrams show the externally visible behavior of a system and the scenarios in which the system will interact with persons or other systems. Their purpose is to help you find and understand requirements better. The diagram illustrates the proposed purposes of a system (use cases) and the actors that are required for their implementation. In addition, you can model personas to represent real users and assume the role of actors.

The diagram can be opened:

  • via double-clicking on the diagram
The diagram

The most important editing functions
Add Existing Elements Enables adding existing use cases, actors or personas to the diagram.
Create Use Case Creates a new use case and adds it to the diagram.
Create Actor Creates a new actor and adds it to the diagram.
Create Persona Creates a new persona and adds it to the diagram.
Create Persona Scenario Creates a new persona scenario and adds it to the diagram.
Create Test Case is used to create new test cases that are copied directly to the diagram.
Create Requirement Creates a new requirement and adds it to the diagram. Your default stereotype is Requirement. In the expanded state, the description of the requirement and, if applicable, the element fulfilling the requirement – for example, a class or a block – are also displayed. For the compliant element to be displayed, there must be a satisfy relationship between the requirement and a class or block in a class or block diagram.
Create Note Creates a note in the diagram.
Create Generalization (use case) Models a generalization between two use cases. First click the generic use case (parent) and then the specialized use case (child). Special use cases inherit all properties of the general use case.
A generalization is represented in the application diagram by a blue line with an arrow. The arrowhead points to the inheriting application.
Create Include Relationship Connects two use cases by an include relationship. First click the use case that should include the other, then the use case to be included. The default stereotype for “Contains” relationships is “include”. A “Contains” relationship is represented by a dashed red line with an arrow. The arrowhead points to the use case contained in the other.
Create Communicate Relationship A communicate relationship is created between use cases and actors. It expresses that an actor can execute or utilize a use case of the system.
Create Note Relationship note relationship helps you show which diagram element an annotation refers to. The link is a dashed gray line.
Create Extend Relationship Connects two use cases to an extend relationship. First click the extended and then the extending use case.
If a use case A extends a use case B, then use case B can be equipped with the features  of use case A. The default stereotype for extend relationships is «extend». An extend relationship is symbolized by a dashed green line with an arrow pointing toward the use case which is extended by an other use case.
Create Satisfy Relationship  Links a requirement to the use case and documents which use case fulfills a requirement.
A fulfillment relationship is an olive green dashed line with an arrow. The arrowhead points to the requirement to be fulfilled. The standard stereotype for a fulfillment relationship is «satisfy».
Create Generalization (actor)  Connects two actors by a generalization. First click the generic actor (parent) and then the specialized actor (child). Special actors inherit all properties of the general actor.
A generalization is represented in the use case diagram by a blue line with arrow. The arrowhead points to the inheriting actor.
Create Persona Relationship Connects an actor to a persona.
Create Persona-Scenario Relationship Connects a persona with a persona scenario. A scenario relationship is modeled between a persona and a persona scenario. It shows the possible scenarios that a persona experiences during a use case.
Create Specialization Connects a persona scenario with a use case. A specialization is modeled between a use case and a persona scenario. It shows which use case is experienced by the persona in the scenario.
Create Derive Relationship Connects a use case to a requirement by a derive relationship. First click the requirement and then the use case.
derive relationship illustrates that a requirement was derived from one or more use cases. A derive relationship is symbolized by a solid green line with an arrow pointing toward the use case from which the requirement was derived. The default stereotype for derive relationships is «derive».