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 Bank clientBank system Withdraw Transfer Balance check deposit

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.

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

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

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

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

Association Relationship Shown by a line connecting actors to use cases

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

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

Example : Extend Relationship

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

Example

Activity Diagram

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

Activity Diagram Notations

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

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

show who has responsibility for each activity. (role) 1.A salesperson calls the client and sets up an appointment 2.Onsite appointment(In the consulting firm’s office) - corporate technicians prepare a conference room for a presentation 3.Offsite appointment(at the client’s office) - a consultant prepares a presentation on a laptop 4.The consultant and the salesperson meet with the client at the agreed-upon location and time 5.the salesperson follows up with a letter 6.If the meeting has resulted in a statement of a problem, the benefit – the activities of each role are clarified Swimlanes 9

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

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

Example

Sequence Diagram

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

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

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

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

Sequence diagram example Object Message Activation Time constraint Comment

Example Sequence for “withdraw-money” use case