Use Case Diagrams
| Use-case diagrams shows interaction between a user (human or machine) and the system. |
Use case diagrams describe the functionality of the new system that you are going build.
NotationsActor: An actor typically represents a user or another system that will interact with the system.
Use case: Use case is a set of scenarios that complete a task. One Use case can include or extend to another Use case
Association: Relations between an actor and a Use case and a Use case if self.
Boundary: Is a scope boundary of the set of use cases
When to use?Use cases should be used in analysis phase, requirements gathering & analysis and project planning.
For domain modeling.
Who develops it?Domain Experts.
Example:Following example shows patient appointment booking functionality.
Further readings:Writing Effective Use Cases -- Alistair Cockburn
UML Distilled -- Martine Fowler
The Unified Modeling Language User Guide --Grady Booch , James Rumbaugh , Ivar Jacobson