Use Case Diagrams

• External actors outside the box representing current system
• Use cases for the system inside the box
• Determine the functionality of the system as seen by actors communicating to it
• Communication association between actors and use cases
• Generalisation relationship between use cases
• Extend and Include relationship between use cases
• Documentation property: textual documentation of functionalities
• Sequence, collaboration and activity diagrams associated with the use case diagram for information on flow of events
• Use case model package containing use cases and actors with relations among them.