Week 2 - Use Case Diagrams Flashcards
What is the fundamental concept behind use case diagrams?
They express stakeholder expectations and are essential for detailed design in object-oriented development methods.
During which process are use case diagrams utilized?
They are utilized during the system analysis and design process.
What three main questions do use case diagrams answer?
1) What is being described? (the system)
2) Who interacts with the system? (the actors)
3) What can the actors do? (the use cases)
What are the components of a use case system diagram structure?
System, Actors, and Use Cases.
Are actors part of the system?
No, actors are outside the system boundaries.
How do actors interact with the system?
Through use cases or by being used by use cases, acting as a function for that use case.
Can actors adopt multiple roles?
Yes, actors can adopt and set aside multiple roles simultaneously.
What are the types of actors in use case diagrams?
Human and non-human (e.g., email servers). They can also be primary, secondary, active, or passive.
How are actors connected to use cases?
Via binary associations represented by solid lines.
What does an ‘Includes Relationship’ signify?
The behavior of an included use case is integrated into the behavior of another base use case.
What does an ‘Extends Relationship’ signify?
One extending use case may integrate with another base use case, but integration is conditional and not mandatory.
What happens in the generalization of use cases?
A use case inherits behaviors and relationships from another, and it can extend or override those behaviors.
Can abstract use cases be executed directly?
No, only the inheriting use case can be executed.
What does the generalization of actors allow?
It allows actors to inherit roles and communication abilities from other actors.
What are the key elements in the structured approach to use cases?
- Name,
- Short Description,
- Precondition,
- Postcondition,
- Error Situations,
- System State on Error,
- Actors,
- Trigger,
- Standard Process,
- Alternative Process.
What questions help identify actors in a system?
1) Who uses the main use cases?
2) Who needs system support for daily work?
3) Who is responsible for system administration? 4) Which external devices or systems does the system communicate with?
5) Who is interested in system results?
What questions help identify use cases?
1) What are the main tasks of an actor?
2) Does an actor want to query or modify system information?
3) Does an actor want to inform the system about external changes?
Why should use cases not model workflows?
Use cases focus on user interactions and not on processes or workflows.
Where are actors positioned in use case diagrams?
Outside the system boundaries.
What is the role of use case diagrams in object-oriented development?
They are essential for expressing stakeholder expectations and guiding detailed design.
How do actors provide functionality to use cases?
By acting as a function to the use case or directly interacting with the system.