Unified Modeling Language (UML) Introduction and Use Case ...csce.uark.edu/~mqhuang/courses/3513/s2011/lectures/SE_Lecture_… · Introduction Use Case Diagram What is UML? UML is

IntroductionUse Case Diagram

Unified Modeling Language (UML)Introduction and Use Case Diagram

Miaoqing HuangUniversity of Arkansas

Spring 2011

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Outline

1 Introduction

2 Use Case Diagram

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Outline

1 Introduction

2 Use Case Diagram

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What is UML?

UML is a modeling languageA model is an abstraction describing a systemModeling language is used to express design

Use notation for depicting models

UML is the de facto modeling language in software engineeringCreated and managed by the Object Management Group, now atversion 2.3 (May 2010)Key persons: (three amigos) James Rumbaugh, Grady Booch,Ivar Jacobson

UML includes a set of graphical notation techniques to createvisual models of software-intensive systems

14 diagrams7 structural diagrams7 behavior diagrams

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UML Diagrams

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UML Diagrams – Example

use case diagram class diagram sequence diagram

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UML Diagrams – Example

Use case diagramDescribe the functional behavior of the system as seen by theuser

Class diagramDescribe the static structure of the system: Objects, attributes,associations

Sequence diagramDescribe the dynamic behavior between objects of the system

State machine diagramDescribe the dynamic behavior of an individual object

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UML Core Conventions

All UML Diagrams denote graphs of nodes and edgesNodes are entities and drawn as rectangles or ovalsRectangles denote classes or instances

Ovals denote functionsNames of Classes are not underlined

SimpleWatchFirefighter

Names of Instances are underlinedmyWatch:SimpleWatchJoe:Firefighter

An edge between two nodes denotes a relationship between thecorresponding entities

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Use Case Diagram

Use case diagrams represent the functionality of the systemfrom user’s point of view

WatchUser

Actor

Use case

ReadTime

SetTime

ChangeBattery

WatchRepairPerson

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Class Diagram

Class diagrams represent the structure of the system

12

push()release()

1

1

blinkIdxblinkSeconds()blinkMinutes()blinkHours()stopBlinking()referesh()

LCDDisplay BatteryLoad

1

2

1

TimeNow

1

Watch

Operations

statePushButton

Attribute

ClassAssociation

Multiplicity

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Sequence Diagram

Sequence diagrams represent the behavior of a system asmessages (“interactions”) between different objects

Message

:Time:Watch:WatchUser

Object

Activation

Actor

pressButton1()

Lifeline

blinkHours()

pressButton2()incrementMinutes()

:LCDDisplay

pressButton1and2()commitNewTime()

stopBlinking()

refresh()

pressButton1()blinkMinutes()

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State Machine Diagram

State machine diagrams represents behavior of a single objectwith interesting dynamic behavior

State

Initial state

Final state

Transition

Event

button1&2Pressed

button1Pressed

button2Pressed

button2Pressed

button2Pressed

button1Pressed

button1&2Pressed IncrementMinutes

IncrementHours

BlinkHours

BlinkSeconds

BlinkMinutes

IncrementSeconds

StopBlinking

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Outline

1 Introduction

2 Use Case Diagram

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What is a use case?

ScenarioA sequence of steps describing an interaction between a user anda system

The customer browse the catalog and adds desired items to the shoppingbasket. When the customer wishes to pay, the customer describes theshipping and credit information and confirms the sale. The systemchecks the authorization on the credit card and confirms the sale bothimmediately and with a follow-up email.

Use caseA use case is a set of scenarios tied together by a common usergoal

Buy a Product use case: a successful purchase or authorizationfailure

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Describe a use case

A set of scenarios in the Use Case “Buy a product online”:1. Customer browses through catalog and selects items to buy2. Customer goes to check out3. Customer fills in shipping information4. System presents full pricing information, including shipping5. Customer fills in credit card information6. System authorizes purchase7. System confirms sale immediately8. System sends confirming email to customer

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An Example

uc Use Cases

System Boundary

OrderFood

CookFood

OrderWine

ServeFood

ServeWine

EatFood

DrinkWine

Pay forFood

Pay forWine

Waiter

Chef

Client

Cashier

receive order

confirm order

facilitate payment

pay

accept

payment

place order

<<extend>> {if wine was ordered}

<<extend>>

<<extend>>

{if wine was

served}

<<extend>>{if wine

was consumed}

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Actor and Use Case

An actor is a role that a user play with respect to thesystemActors are connected to the use cases by a line

A single actor may perform many use casesA use case may have several actors performing it

Four types of relationships in use case diagramGeneralization between use casesGeneralization between actorsInclude relationship between use casesExtend relationship between use cases

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Generalization between use cases

Different versions of a use case share some actions in commonand have some that are unique to each one

Generalized use case: abstract use caseIt may never exist in a real system

Specialized use case: concrete use case

Pay utility bill

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Generalization between Actors

Specialized actor can do everything the generalactor can do, and more

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Include Relationship between Use Cases

One use case includes the functionality of another use caseInvocation of one use case by another one

e.g., calling a function or invoking an operation within source code

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Extend Relationship between Use Cases

One use case may be extended by the functionality in anotheruse case

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Include, Generalization, Extend

IncludeUse include when you are repeating yourself in two or moreseparate use cases and you want to avoid repetition

GeneralizationUse Generalization when you are describing a variation on normalbehavior and you wish to describe it casually

ExtendUse extend when you are describing a variation on normalbehavior and you wish to use the more controlled form, declaringyour extension points in your base use case

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Unified Modeling Language (UML) Introduction and Use Case ...csce.uark.edu/~mqhuang/courses/3513/s2011/lectures/SE_Lecture_… · Introduction Use Case Diagram What is UML? UML is

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