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Objects Object means a combination of data and logic that

represent some real world entity

Eg. Saab Automobile can be represented in a computerprogram as an object.

The data part of this object would be the cars name,colour, number, price

The logic part could be a collection of program Show mileage, change mileage, stop, go

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Objects

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Object Attribute/data Behaviors/logic

Book with title

Object OrientedAnalysis Design

Rent,

available,

reserved

Add(),

Update(),


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Class Classes are used to distinguish one type of object from

another.

A class is a set of object that share a common structure

and common behaviour.

A single object is simply an instance of a class.

The chief role of a class is to define the properties andprocedure and applicability of an instances

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Object Behaviour and methods

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Employee16

name: John

address: M Street No.23

dateOfBirth: 02/10/65

employeeNo: 324

socialecurityNo:E342545

department: Sale

Eployee16.join(02/05/1997)Eployee16.retire(03/08/2005)

Eployee16.changeDetail(X

Street No. 12)

Object State and properties

Employee

name: String

address: String

dateOfBirth: Date

employeeNo: int

socialecurityNo:String

department: String

Join();

Retire();

changeDetail();


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Object Respond to Messages Objects capabilities are determined by the methods

define for it.

Methods conceptually are equivalent to the functiondefinitions used in procedural languages.

To do an operation ,a message is sent to an object

Eg: car object knows how to respond to the stop

message,

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What is Abstraction?

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Salesperson

Not saying

Which

salesperson

just asalesperson

in general!!!

CustomerProduct


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What is Encapsulation? Hide implementation from clients Clients depend on interface

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Improves Resiliency

How does an object encapsulate?What does it encapsulate?


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Inheritance Object classes may inherit attributes and services from

other object classes.

Inheritance represents the generalization of a class.

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Inheritance Object classes may inherit attributes and services from

other object classes.

Inheritance represents the generalization of a class.

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A generalisation hierarchy

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Employee

Programmer

projectprogLanguage

Manager

ProjectManager

budgetsControlled

dateAppointed

projects

Dept.Manager

StrategicManager

dept responsibilities


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Multiple inheritance Rather than inheriting the attributes and services

from a single parent class, a system which supports

multiple inheritance allows object classes toinherit from several super-classes

Can lead to semantic conflicts whereattributes/services with the same name in different

super-classes have different semantics Makes class hierarchy reorganisation more

complex

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Multiple inheritance

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# Tapes

Talking book

AuthorEdition

Publication date

ISBN

Book

SpeakerDurationRecording date

Voice recording


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Advantages of inheritance

It is an abstraction mechanism which may be used toclassify entities

It is a reuse mechanism at both the design and theprogramming level

The inheritance graph is a source of organisationalknowledge about domains and systems

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Polymorphism

the ability of different objects to perform theappropriate method in response to the samemessage is known as polymorphism.

the selection of the appropriate method depends

on the class used to create the object

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Shape

SquareCircle

name

getName( )

calculateArea( )

side

calculateArea( )

radius

calculateArea( )


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Object Relationships and Association

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pilot Planes

Association represent the relationship betweenobjects and classes

Association are bidirectional that they means they

can be traversed in both directions.An important issue is cardinalitywhich specifies how

many instances of one class may relate to a singleinstance of an associated class

Can Fly flown by


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What is OOAD?

Object-oriented analysis and design (OOAD) is asoftware engineering approach that models a system as agroup of interacting objects .

Analysisunderstanding, finding and describingconcepts in the problem domain.

Designunderstanding and defining softwaresolution/objects that representthe analysis concepts andwill eventually be implemented in code.

OOADAnalysis is object-oriented and design isobject-oriented. A software development approach thatemphasizes a logical solution based on objects.

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Definitions of OOA and OODWhat is Object Oriented Analysis? Object-oriented analysis (OOA) applies object-modeling

techniques to analyze the functional requirements for a

system.

What is Object Oriented Design?

Object-oriented design (OOD) elaborates the analysis

models to produce implementation specifications.

OOA focuses on what the system does, OOD on how thesystem does it.

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Object Oriented Design OOD transforms the analysis model created using OOA

into a design model that serves as a blueprint for softwareconstruction.

OOD results in a design that achieves a number of differentlevels of modularity.

Subsystems: Major system components. Objects: Data and the operations. Four important software design concepts:

Abstraction Information Hiding Functional Independence Modularity

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C i


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Comparison

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OO:

Systems decomposed intocollections of data objects;

function + data in one place =>

System components more

independent => more resilient

to requirements and

maintenance changes.

Inheritance and polymorphism

are possible => reuse,

extension, and tailoring of

software/designs is possible.

Closely mirrors how humans

decompose and solve

complex.

Structured:

Systems decomposed into functions;functions and data modelled separately

=>

System components are more

dependent on each other =>

requirements and

maintenance changes more

difficult

Inheritance and polymorphism

not possible => limited reuse

possible.

System components do not

map closely to real-world

entities => difficult to manage

complexity.


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Comparison

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OO:

Process allows foriterative andincremental development =>

Integration of programs is

series of incremental

prototypes. Users and developers get

important feedback

throughout development.

Testing resources distributed

more evenly.

If time is short, coding and

testing can begin before the

design is finished.

Structured:

Process less flexible and largely linear=>

Integration of programs is big

bang effect.

Users or developers providedwith little or no feedback; see

system only when it has been

completed.

Testing resources are

concentrated in the

implementation stage only.

Coding and testing cannot

begin until all previous stages


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OOD

The subsystem layer:Representation of each of thesubsystems that enable thesoftware to achieve its customerdefined requirements.

The class and object layer: Theclass hierarchies, (generalization)

and representation of objects. The message layer: The design

details of communication of eachobject with its collaborators.(external and internal interfaces)

The responsibilities layer: DataStructure and algorithmic designfor all attributes and operations.

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OOA to OOD

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OOA to OOD

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Design Issues decomposabilitythe facility with which a design methodhelps the designer to decompose a large problem intosubproblems that are easier to solve;

composabilitythe degree to which a design method

ensures that program components (modules), oncedesigned and built, can be reused to create other systems; understandabilitythe ease with which a program

component can be understood without reference to otherinformation or other modules;

continuitythe ability to make small changes in a program

and have these changes manifest themselves withcorresponding changes in just one or a very few modules; protectiona architectural characteristic that will reduce

the propagation of side affects if an error does occur in agiven module.

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Process Flow for OOD

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http://www.intelligroup.com/http://www.intelligroup.com/


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Unified Modeling Language

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UML Di


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UML DiagramWhat is UML?The Unified Modeling Language (UML) is a standard language for

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Specifying Visualizing Constructing Documenting

Business Modeling Communications


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Different Views

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Users Designers Analyzers


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UML- Eight Diagrams and One

Language Use Case Diagram

Class Diagram/Object Diagram

State Diagram

Sequence Diagram

Collaboration Diagram

Activity Diagram

Component Diagram

Deployment Diagram

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Use case diagram

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Online C2C shopping

overview the usage requirements

presentations project stakeholders

"the meat" of the actual requirements

Actor

Actor:

An actor is a person, organization, or

external system that plays a role inone or more interactions with your

system

Use case

Use case:

A use case describes a sequence of

actions that provide something ofmeasurable value to an actor and is

drawn as a horizontal ellipse

Systemboundary

System boundary:

indicates the scope of your

system. Anything within the boxrepresents functionality that is in

scope and anything outside the box

is not


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Class Diagram

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Class diagrams show the classes of the

system, their interrelationships (including

inheritance, aggregation, and

association), and the operations andattributes of the classes.

Name

Attributes

Operations

Relations

Associations

Aggregation

Generalization


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Relationships between Class Diagrams

Association -- a relationship between instances of the two classes. Thereis an association between two classes if an instance of one class mustknow about the other in order to perform its work. In a diagram, an

association is a link connecting two classes.

Aggregation -- an association in which one class belongs to a collection.An aggregation has a diamond end pointing to the part containing thewhole.

Generalization -- an inheritance link indicating one class is a superclassof the other. A generalization has a triangle pointing to the superclass.

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Activity Diagram

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Activity diagrams describe the

workflow behaviour of a system

Start

Fork

Branch

MergeJoint

End


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State Machine DiagramAState Machine diagram

shows the possible states of

the object and the transitions

that cause a change in state.

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?What is different

between activities

and Statemachinediagram


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Sequence DiagramA Sequence diagram depicts the sequence of actions

that occur in a system. The invocation of methods ineach object, and the order in which the invocation

occurs is captured in a Sequence diagram.

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Collaboration Diagram The collaboration diagram illustrates messages being

sent between classes and objects (instances).

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Component DiagramAcomponent diagram in the Unified Modeling

Language, depicts how components are wired togetherto form larger components and or software systems.

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Deployment Diagram deployment diagram specifies a set of constructs that

can be used to define the execution architecture ofsystems that represent the assignment of software

artifacts to nodes.

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QUESTIONS

Documents

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