The document discusses use case diagrams and modeling. It defines key concepts like use cases, actors, and their relationships. Use cases specify system functions from the user's perspective, while actors represent roles that interact with the system. Use case diagrams visualize system behavior, help capture requirements, and serve as a basis for testing and communication between developers and users.

1. Use Case Diagram
SE
Usman Rafi

5. History
• CASE Tools: Automation of Software Development
• People-to-People
• People-to-Computer
• Rational Software (An IBM Company)
• Rational Rose / MS Visio:
Converting UML-Diagrams-to-Programs

6. History
• Booch: Booch Method
• Rumbaugh: OMT (object modeling tech.)
• Jacobson: OOSE (OO software engrg.)
• Three amigos: UML

7. History
• UML: an open standard controlled by OMG
• UML 1.0 (1997)
• UML 2.0 (2004)

9. USE CASE MODELLING
-functional reqts., analysis phase
- what a system does: functions represented as use cases
- Actor: external agent that interacts with the system, exchanges info. with
the system (user, sub-system, etc.)
- a role played by user
Note: a use case represents a complete functionality.
• view of system behavior from an external person’s viewpoint
• effective tool for validating requirements
• an effective communication tool
• basis for a test plan
• basis for user manual
Developing the use cases in not difficult; ensuring that you have them all
is murder.

10. Use cases help ..
· Capture the system's functional requirements
from the users' perspective
· Actively involve users in the requirements-
gathering process
· Provide the basis for identifying major classes
and their relationships
· Serve as the foundation for developing system
test cases

11. Use Case Diagrams
• Use case diagrams are used to visualize, specify, construct, and
document the (intended) behavior of the system, during
requirements capture and analysis.
• Provide a way for developers, domain experts and end-users to
Communicate.
• Serve as basis for testing.
• Use case diagrams contain use cases, actors, and their relationships.

16. Use Case
• Use cases specify desired behavior.
• A use case is a description of a set of sequences of actions, including
variants, a system performs to yield an observable result of value to
an actor.
• Each sequence represent an interaction of actors with the system.
name

18. Actors
• An actor represents a set of roles that users of use case play when
interacting with these use cases.
• Actors can be human or automated systems.
• Actors are entities which require help from the system to perform
their task or are needed to execute the system’s functions.
• Actors are not part of the system.
name

19. Use Cases and Actors
• From the perspective of a given actor, a use case does something that
is of value to the actor, such as calculate a result or change the state
of an objects

20. Example of Use Case Diagram
student
registration
updating
grades
output
generating
faculty

21. Use-Case Diagrams (POST)
CustomerCashier
Buy Item
Log In
Refund a Purchased Item
POST
Use Case
System Boundary
Adapted from Larman “Applying UML and Patterns”
POST: Point of Sale Terminal

22. Alternate HACS
Instructor
Student
System Admin
MH
Configure HACS
Distribute Asignments
Post Solutions
Distribute Grade
Remind Student
Submit Assignment
HACS

23. Black Box Use Cases
• Most common and recommended
• Black box use cases do not describe internal working of a system and
components
• System is defined with the help of responsibilities
• Responsibilities help to identify what the system will do (functional
requirement) not how the system will do it
• Analysis – What?
• Design – How?
• During requirement analysis HOW is omitted
• Only behavior is specified

24. Example