unit 4 (OOSE)

 

1. Object-Oriented Design (OOD)

Definition

Object-Oriented Design (OOD) is the process of converting the analysis model into a design model by identifying classes, objects, relationships, and interactions.

Objectives

1. Identify classes and objects.
2. Define relationships among classes.
3. Design system architecture.
4. Improve reusability.
5. Reduce complexity.
6. Support maintenance.
7. Improve software quality.

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2. Conventional v/s Object-Oriented Design

Conventional Design	OO Design
Function-oriented	Object-oriented
Focus on functions	Focus on objects
Data and functions are separate	Data and functions are together
Less reusable	More reusable
Difficult maintenance	Easy maintenance
Uses DFD and flowcharts	Uses UML diagrams
Less flexible	More flexible

7-Mark Answer

Conventional vs OO Design

1. Conventional design is function-oriented.
2. OO design is object-oriented.
3. Conventional design separates data and functions.
4. OO design combines data and functions.
5. Conventional design has low reusability.
6. OO design has high reusability.
7. OO design is easier to maintain and extend.

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3. CRC Cards

CRC = Class + Responsibilities + Collaborators

CRC cards are used to identify classes, their responsibilities, and collaborating classes.

Components

Class

Represents an object type.

Responsibilities

Tasks performed by the class.

Collaborators

Other classes that help perform tasks.

Example

Class	Responsibilities	Collaborators
Student	Register Course, View Result	Course
Course	Store Course Details	Student

Advantages

1. Easy to understand.
2. Helps identify classes.
3. Improves team communication.
4. Supports object-oriented design.
5. Reduces design errors.

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4. Class Diagram

Definition

A Class Diagram represents classes, attributes, methods, and relationships in a system.

Components

1. Class Name
2. Attributes
3. Methods
4. Relationships

Example

-----------------
|   Student     |
-----------------
| RollNo        |
| Name          |
-----------------
| Register()    |
| Display()     |
-----------------

Advantages

1. Shows system structure.
2. Easy to understand.
3. Supports code generation.
4. Improves design quality.

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5. Interaction Diagram

Definition

An Interaction Diagram shows communication between objects to perform a task.

Types

1. Sequence Diagram
2. Collaboration Diagram

Sequence Diagram Example

Student -> Login Page
Login Page -> Database
Database -> Login Page
Login Page -> Student

Advantages

1. Shows object interaction.
2. Displays message flow.
3. Helps understand system behavior.
4. Easy debugging.

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6. State Chart Diagram

Definition

A State Chart Diagram shows different states of an object and transitions between them.

Example: ATM Card

Idle
 |
Insert Card
 |
PIN Verification
 |
Transaction
 |
Eject Card
 |
End

Advantages

1. Shows object states.
2. Represents dynamic behavior.
3. Easy to understand lifecycle.
4. Helps in system modeling.

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7. Component Diagram

Definition

A Component Diagram shows software components and their dependencies.

Components

1. User Interface
2. Business Logic
3. Database

Example

User Interface
      |
Business Logic
      |
Database

Advantages

1. Shows software architecture.
2. Improves modularity.
3. Supports maintenance.
4. Easy deployment planning.

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8. Deployment Diagram

Definition

A Deployment Diagram shows physical deployment of software on hardware nodes.

Example

Client PC
    |
Application Server
    |
Database Server

Advantages

1. Shows hardware structure.
2. Helps deployment planning.
3. Improves system understanding.
4. Supports distributed systems.

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9. ATM Case Study

Main Classes

1. Customer
2. ATM
3. Account
4. Transaction

Functions

1. Insert Card
2. Enter PIN
3. Check Balance
4. Withdraw Cash
5. Deposit Money
6. Transfer Funds
7. Print Receipt

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10. Payroll System Case Study

Main Classes

1. Employee
2. Payroll
3. Salary
4. Department

Functions

1. Employee Registration
2. Attendance Management
3. Salary Calculation
4. Tax Deduction
5. Payroll Generation
6. Report Generation
7. Salary Slip Printing

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11. Course Registration System Case Study

Main Classes

1. Student
2. Course
3. Registration
4. Faculty

Functions

1. Student Login
2. Course Selection
3. Registration
4. Fee Payment
5. View Course List
6. View Result
7. Course Management

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RGPV Most Important 7-Mark Questions

1. Compare Conventional Design and OO Design.
2. Explain CRC Cards with example.
3. Explain Class Diagram with suitable example.
4. Explain Interaction Diagram and its types.
5. Explain State Chart Diagram with example.
6. Explain Component Diagram and Deployment Diagram.
7. Explain ATM System Case Study.
8. Explain Payroll System Case Study.
9. Explain Course Registration System Case Study.

Exam Tip: For every 7-mark answer write:

• Definition (2 lines)
• 5–7 key points
• Small diagram/example

This format usually fits RGPV evaluation style and helps score better.