Copyright ©2004 Cezary Z Janikow 1 OOAD Overview n OO language – Necessary for OO systems? –...

Copyright ©2004 Cezary Z Janikow 1

OOAD Overview

OO language

– Necessary for OO systems?

– Sufficient for OO systems?

Owning a hummer doesn’t make you a home builder

OOAD is necessary in building QUAILITY OO systems

– Architectural cohesion

– Reusability

– Maintenance


OOAD Overview

Key importance– Assignment of Responsibilities

Performed during Design workflow

Responsibility-driven design

Follows GRASP principles

Successful designs become Patterns

Key elements and properties– Use Cases

Text description of vital transactions and scenarios

Not OO but usually used in OOAD

– Agile Process

Light, flexible, iterative form of the UP process

Iterative – performed in a number of successive builds


OOAD Overview

OOAD elements

Topics and Skills

UML notation

Requirements analysis

Principles and guidelines

Patterns

Iterative development with an agile Unified

Process

OOA/D


OOAD Overview

Analysis -> Design -> Implementation -> Deployment

– Analysis is investigation of the problem, requirements, constraints, technology

Emphasis on finding problem entities (conceptual classes), relationships, constraints

– Design is a conceptual solution, including architecture, algorithms, etc.

Emphasis on designing classes and objects with behavior to allow collaborations to solve particular requests while using patterns

– Implementation is expression of the design in code

Emphasis on utilizing the language of choice to implement design classes while exploring visibility, navigability, etc.

– Deployment is the actual installation in the host environment


OOAD Overview

Airplane example of object and class discovery

Plane

tailNumber

public class Plane{private String tailNumber;

public List getFlightHistory() {...}}

domain concept

visualization of domain concept

representation in an object-oriented programming language


OOAD Example

Rudimentary process

– UseCases -> DomainModel -> Interactions -> DesignModel

Dice game example

– 2 players rolling 2 dice

Use Case

– Verbal description of transactions or processes

– Player throws two dice. The result is observed. If the total is 7 the player wins otherwise he loses.


OOAD Example

Domain Model

– Static view of classes and relations

Player

name

DiceGame

Die

faceValue

Rolls

Plays

Includes

2

2

1

1

1

1


OOAD Example

Interactions

– Assignment of responsibilities among objects

– Sequence or Communication diagrams

:DiceGame

play()

die1 : Die

fv1 := getFaceValue()

die2 : Die

roll()

roll()

fv2 := getFaceValue()


OOAD Example

Design Diagrams

Software classes with methods according to responsibilities and attributes according to visibility

2

Die

faceValue : int

getFaceValue() : introll()

DiceGame

die1 : Diedie2 : Die

play()

1


UML UML

Visual Modeling Language

InterfaceX

AbstractClassX

...

«interface»InterfaceX

operation1()

ClassA ClassBAssociation-name role-1 role-2

1 1

zero ormore;"many"

one ormore

one toforty

exactlyfive

Class ClassClass Class* 1..*1..40 5

Whole

Part

1

*

AssociationClass

Composition

Multiplicity:

Associations:

ClassX

classAttribute+ publicAttribute- privateAttributeattributeWithVisibilityUnspecifiedattribute1 : typeburgers : List of VeggieBurgerattribute2 : type = initial valuefinalConstantAttribute : int = 5 { frozen }/derivedAttribute

classMethod()+ «constructor» ClassX(int)«signal» CaughtException1()methodWithVisibilityUnspecified()methodReturnsSomething() : FooabstractMethod()abstractMethod2() { abstract } // alternate+ publicMethod()- privateMethod()# protectedMethod()~ packageVisibleMethod()finalMethod() { leaf }methodWithoutSideEffects() { query }synchronizedMethod() { guarded }

exceptionsThrownException1

AlternateUMLForAbstractClass

{abstract}

...

ClassY

operation1()...

generalization interfaceimplementation

AlternateUMLForImplOfInterfaceX

operation1()

FinalClass{leaf}

...


UML Three perspectives (and class meanings in diagrams)

Conceptual – described the real world entities

Specification – describes design entities but not tied to specific implementations

Implementation – describes particular implementations of the specification elements

Conceptual Perspective(domain model)

Raw UML class diagram notation used to visualize real-world concepts.

Specification or Implementation

Perspective(design class diagram)

Raw UML class diagram notation used to visualize software elements.

2

Die

faceValue : int

getFaceValue() : introll()

DiceGame

die1 : Diedie2 : Die

play()

DiceGame Die

faceValue

Includes 21

Copyright ©2004 Cezary Z Janikow 1 OOAD Overview n OO language – Necessary for OO systems? –...

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