Describes system behaviour
Uses natural languages
Actor
- A use case is always triggered by external entity called actor
- Acts as a black box and cannot be changed
Communication line
System Boundaries
- Separation between actors and use cases
- Marked by a bounded box around the use cases
Guideline for use case
- Start with a goal
- Write use cases as narratives
- Use simple language
- Keep the technology specifics out
- Don’t include UI elements in use cases
- Every use case should give one guarantee about the behaviour of the system
- Actors don't interact with each other
- Primary actors on left side of the diagram and secondary actors on the right
- Place use case in logical order
- Place included use cases to the right of the invoking use case
- Place inheriting use case below parent use case