IT 21103/41103IT 21103/41103

System Analysis & DesignSystem Analysis & Design

Chapter 05Chapter 05

Object ModelingObject Modeling

Chapter 05Chapter 05

Object Modeling combines the Object Modeling combines the

DFD & ERD into oneDFD & ERD into one

Chapter 05Chapter 05

Object Modeling in Small Enterprise Object Modeling in Small Enterprise Systems is rare, but driven by Systems is rare, but driven by

object-programmingobject-programming

Chapter 05Chapter 05

The Design & Development Phases The Design & Development Phases of the System Analysis are of the System Analysis are

dependent on good modeling in the dependent on good modeling in the Analysis PhaseAnalysis Phase

Chapter 05Chapter 05

Object Modeling is vital if you plan Object Modeling is vital if you plan to program with Object based to program with Object based

development toolsdevelopment tools

Chapter 05Chapter 05

ObjectsObjects

Have two components:Have two components:

AttributesAttributes

BehaviorsBehaviors

Chapter 05Chapter 05

AttributesAttributes

Equal to Fields in a DatabaseEqual to Fields in a Database

Chapter 05Chapter 05

BehaviorsBehaviors

Composed of program instructions Composed of program instructions called Methodscalled Methods

Chapter 05Chapter 05

MethodsMethods

Respond to events by other users Respond to events by other users or other objectsor other objects

Chapter 05Chapter 05

Object-Oriented Analysis (OOA)Object-Oriented Analysis (OOA)

Identifying objects and how they Identifying objects and how they work together to produce work together to produce

informationinformation

Chapter 05Chapter 05Objects:Objects:

ClassClassInstanceInstance

EncapsulationEncapsulationMessagesMessages

PolymorphismPolymorphismInheritanceInheritance

RelationshipsRelationships

Chapter 05Chapter 05Class:Class:

Abstract of a real-worldAbstract of a real-world

PersonPerson

PlacePlace

ThingThing

ActivityActivity

Chapter 05Chapter 05Class:Class:

Two ComponentsTwo Components

Data AttributesData Attributes

Fields in a DatabaseFields in a Database

MethodsMethods

Services performed by the class Services performed by the class membermember

Chapter 05Chapter 05Instance:Instance:

A specificA specific

Person, Place, Thing or ActivityPerson, Place, Thing or Activity

Created from the Class TemplateCreated from the Class Template

Chapter 05Chapter 05Encapsulation:Encapsulation:

The environment where the Class The environment where the Class liveslives

Functions associated with MethodsFunctions associated with Methods

Chapter 05Chapter 05Encapsulation:Encapsulation:

Methods have two types:Methods have two types:

#1#1

Perform input/output servicesPerform input/output services

To communicate with other objects To communicate with other objects outside the membrane outside the membrane

Chapter 05Chapter 05Encapsulation:Encapsulation:

Methods have two types:Methods have two types:

#2#2

Perform behavior services to Perform behavior services to manipulate data inside the manipulate data inside the

membrane membrane

Chapter 05Chapter 05Messages:Messages:

How objects communicate with How objects communicate with each othereach other

(E-Mail)(E-Mail)

Chapter 05Chapter 05Polymorphism:Polymorphism:

Methods can change their behavior Methods can change their behavior depending on the Class they belong depending on the Class they belong

withwith

Chapter 05Chapter 05Inheritance:Inheritance:

Class attributes and methods are Class attributes and methods are inherited by a newly created classinherited by a newly created class

Chapter 05Chapter 05Relationships:Relationships:

How Classes How Classes

Interact with each otherInteract with each other

Inherit attributes & methodsInherit attributes & methods

Cardinality between classesCardinality between classes

Chapter 05Chapter 05An analyst would not need to An analyst would not need to

produce a DFD or ERD if doing produce a DFD or ERD if doing object modelingobject modeling

Chapter 05Chapter 05Object Relationships:Object Relationships:

Collaborative RelationshipCollaborative Relationship

Specialization RelationshipSpecialization Relationship

Aggregation RelationshipAggregation Relationship

Chapter 05Chapter 05Collaborative Relationship:Collaborative Relationship:

One Class provides information to One Class provides information to another Classanother Class

Chapter 05Chapter 05Specialization Relationship:Specialization Relationship:

A Class is a sub-set of another A Class is a sub-set of another Class, where it inherits all of the Class, where it inherits all of the

Parents attributes & methods, but Parents attributes & methods, but may have a few that the Parent may have a few that the Parent

does notdoes not

““Is A”Is A”

Chapter 05Chapter 05Aggregation Relationship:Aggregation Relationship:

When one Class is composed of When one Class is composed of one or more Instances of another one or more Instances of another

ClassClass

““Has A”Has A”

Chapter 05Chapter 05Use Case Modeling:Use Case Modeling:

Developing a model based on task Developing a model based on task scenarios to determine what scenarios to determine what

happens in a particular systemhappens in a particular system

A detailed description of what A detailed description of what happens when something interacts happens when something interacts

with a systemwith a system

Chapter 05Chapter 05Object Modeling SymbolsObject Modeling Symbols

SymbolSymbol CardinalityCardinality

Zero or OneZero or One

Only OneOnly One

Zero or ManyZero or Many

One or ManyOne or Many

Chapter 05Chapter 05Object Modeling SymbolsObject Modeling Symbols

Object Name

Attributes

Methods

Chapter 05Chapter 05Unified Modeling Language (UML)Unified Modeling Language (UML)

Nine TypesNine Types

Chapter 05Chapter 05Class DiagramClass DiagramObject DiagramObject Diagram

Use Case DiagramUse Case DiagramInteractive (Sequence) DiagramInteractive (Sequence) Diagram

Interactive (Collaboration) DiagramInteractive (Collaboration) DiagramStatechart DiagramStatechart Diagram

Activity DiagramActivity DiagramComponent DiagramComponent DiagramDeployment DiagramDeployment Diagram

Chapter 05Chapter 05Data DictionaryData Dictionary

Contains the Data element names Contains the Data element names and their characteristicsand their characteristics

This is part of the documentation This is part of the documentation required for the SDLCrequired for the SDLC

Chapter 05Chapter 05Object DiagramObject Diagram

Shows specific instances of classesShows specific instances of classes(Figure 5-9 – page 134)(Figure 5-9 – page 134)

Chapter 05Chapter 05Questions?Questions?

Chapter 05Chapter 05Assignment # 5Assignment # 5

Page 139Page 139UML – Object DiagramUML – Object Diagram

Due: Oct 19Due: Oct 19thth, 2005, 2005