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Use Case Diagrams

Use Case Diagrams. Use Case. Use case A view to system seen from outside(user) User’s requirements on system A set of scenario for an actor to achieve useful works. Withdraw. Transfer. Balance check. deposit. Bank client. Bank system. Basic Concepts. Actor

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Use Case Diagrams

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  1. Use Case Diagrams

  2. Use Case • Use case • A view to system seen from outside(user) • User’s requirements on system • A set of scenario for an actor to achieve useful works Withdraw Transfer Balance check deposit Bank client Bank system

  3. Basic Concepts • Actor • An external person, process or thing interacting with a system or class • User Case • Each describes a possible interaction between an actor and the system • Use cases are actions that a user takes on a system • System • The entity that we are going to build • Can have subsystems in it • Relationship • Connection between actors and use cases or use cases and use cases.

  4. Actors • A user of the system • a person or another system • Identify the actors in terms of their roles

  5. Use Case • actions users take on system • can be very high level or so fine-grained • Use “verb” or “verb+noun” style naming borrow return

  6. System • module that performs the function • System or the sybsystem is shown as a rectangle enclosing the use cases, with the system name in the rectangle Library System

  7. Relationship (Use Case Diagram) • There are four kinds of relationships • Association • Extend • Include • generalization

  8. Association Relationship • Shown by a line connecting actors to use cases

  9. Include Relationship • Between a use case and another use case • use case A includes the function of use case B (has-a relationship) <<include>> A B

  10. Extend Relationship • Use case can be extended by another use case • At the extension point, use case is extended • Extension point • Shows the exact extension point between the two use cases • Shows the actual logic necessary for one use case to extend another

  11. Example : Extend Relationship

  12. Generalization Relationship • Indicate an inheritance of an item in UML • Can be applied to actors as well as use cases

  13. Example

  14. Activity Diagram

  15. What is Activity Diagram • Shows overall flow of control (just like flowchart) • A simplified look at what happens during a process • Business and operational step-by-step workflows of components in a system

  16. Activity Diagram Notations

  17. Wake Up Wake Up Activity1 [hungry] [Not hungry] [hungry] [Not hungry] Activity2 Eat Breakfast Go Back to Sleep Eat Breakfast Go Back to Sleep Decision Transition from one activity to another Two ways of showing a decision

  18. Work Out Television Remote.keyln(channel) Show New Channel Press Channel Number Shower Relax Change(channel) Change (channel) Watch Concurrent Path , Signal Synchronization bar Signal : when received, the signal causes an activity to take place (send : convex , receive : concave ) Concurrent Path

  19. Swimlanes • show who has responsibility for each activity. (role) • A salesperson calls the client and sets up an appointment • Onsite appointment(In the consulting firm’s office)- corporate technicians prepare a conference room for a presentation • Offsite appointment(at the client’s office)- a consultant prepares a presentation on a laptop • The consultant and the salesperson meet with the client at the agreed-upon location and time • the salesperson follows up with a letter • If the meeting has resulted in a statement of a problem, the benefit– the activities of each role are clarified 9

  20. Activity Diagram Example Call client and set up appointment [appointment offsite] [appointment onsite] Prepare a conference room Prepare a laptop Meet with the client Send followup letter [no statement problem] See the Activity Diagram for Creating a Document [statement of problem] Create proposal Send proposal to client 10

  21. Swimlane : shows “who” for each activity Sales Person Consultant Corporate Technician Call client and set up appointment [appointment onsite] [appointment offsite] Prepare a laptop Prepare a conference room Meet with the client Send followup letter [statement of problem] See the Activity Diagram for Creating a Document Create proposal [no statement problem] Send proposal to client

  22. Example

  23. Sequence Diagram

  24. Purpose of Sequence Diagram • shows the sequence of messages for a particular task from a use case diagram • Understand how use case(scenario)can be refined with detailed information

  25. Sequence Diagram • Time, object, and message • Lifeline and activation :Name Notation

  26. Basics • Focus on order in which messages occur objects time :Name1 object :Name2 message activation lifeline

  27. Messages • The first message starts at the top, typically located on the left side • Subsequent messages are then added to the diagram slightly lower then the previous message • Messages can be sent to itself : synchronous call operation : method on the arrow : asynchronous signal : return message (optional) : return value on the arrow

  28. Sequence diagram example Object Time constraint Message Activation Comment

  29. Example • Sequence for “withdraw-money” use case

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