1. Object Oriented Systems Design
School of Computer Engineering,
KIIT University.

2. Some Great Thoughts !!
“Measuring programming progress by lines of code is like measuring aircraft building progress by weight.” – Bill Gates
“Before software can be reusable it first has to be usable.” – Ralph Johnson
“There are two ways of constructing a software design: One way is to make it so simple that there are obviously no deficiencies, and the other way is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult.” -C.A.R. Hoare
Who gave QUICKSORT & DINING PHILOSOPHERS PROBLEM
SCHOOL Of COMPUTER ENGINEERING KIIT UNIVERSITY

3. AN OVERVIEW OF OBJECT ORIENTED SYSTEMS DEVELOPMENT
CHAPTER - 1
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4. 1.1 Introduction
Software development is dynamic and always undergoes major changes.
Vast number of Tools & Methodologies are available for systems development.
Systems Development refers to all activities that goes into producing an information systems solution.
SCHOOL Of COMPUTER ENGINEERING, KIIT UNIVERSITY

5. 1.1 Introduction (contd….)
Systems development consists of:
Analysis
Design
Modeling
Implementation
Testing &
Maintenance
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6. 1.1 Introduction (contd….)
A Software development methodology is a series of processes that, if followed can lead to the development of an application.
The s/w processes describe how the work is to be carried out to achieve the goal based on system requirements. Each process consists of a number of steps and rules that should be performed during development.
Unified Approach is the methodology used in OOSD.
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7. 1.2 Two Orthogonal Views of the Software
OOSD Methodology:
Views software in the form of objects which are discrete and grouped.
OOSD focuses on the object, which combines data and functionality
Primary focus is on data.
Data security is given utmost attention.
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8. 1.2 Two Orthogonal Views of the Software (contd….)
Traditional Development Technique:
Views software as collection of programs or functions and isolated data.
Algorithm + Data Structure = Program
It focuses on the functions of the system – What is it doing ?
Primary focus is on function.
Data is free flowing.
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9. 1.3 OOSD Methodology
OOSD is a way to develop software by building self-contained modules or objects that can be easily replaced, modified and reused.
OOSD encourages views of the world as a system of cooperative and collaborating objects.
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10. 1.3 OOSD Methodology (contd….)
In an O-O environment software is a collection of discrete objects that encapsulate their data as well as the functionality, to model real-world entity.
In an O-O system everything is an object and each object is responsible for itself.
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11. OO APPROACH We live in a world of objects
Object-Oriented view is an abstraction that models the world in ways that help us to better understand and navigate it
OO approach was first proposed in the late 1960s
As time passes, object technologies are replacing classical software development approaches. Why?
Object technologies lead to reuse, OO software is easier to maintain, to adapt, and to scale.

12. OO Paradigm
For many years, the term OO was used to denote a software development approach that used one of a number of OO programming languages(e.g. Ada 95, C++, Eiffel, Smalltalk)
Today, the OO paradigm encompasses a complete view of software engineering
Although any one of process models, could be adapted for use with OO, the best choice would be an evolutionary process model

13. OO Concepts Classes and class hierarchies Objects Messages Instances
Inheritance
Abstraction and hiding
Objects
Attributes
Methods
Encapsulation
Polymorphism
Messages

14. object-orientation
Using object-orientation as a base, we model a system as a number of objects that interacts.
Object-oriented Methods enable us to create sets of objects that work together synergistically to produce software that better model their problem domains than similar systems produced by traditional techniques.

15. object-orientEd METHODS
A technique for system modelling
A technique to manage complexity inherent in analysis, design, and implementation
For the analysis and design of system
Provide integrated view of hardware and
software
Provide a methodology for system development

16. 1.4 Why an Object Orientation ?
O-O systems are :
Easier to evolve (adapt to changing requirements)
Easier to maintain
Directly related to reality - semantic gap
More robust & promote greater design &
Code reuse
Systems can be developed more rapidly at a lower cost
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17. 1.4 Why an Object Orientation ? (contd….)
Reasons why object orientation works:
Higher level of abstraction. (At object level)
Seamless transition among different phases of software development.
O-O uses same language like UML(Unified Modeling Language) to talk about all phases of software development.
It reduces complexity, redundancy, & creating a robust system.
Encouragement of good programming technique. &
Promotion of reusability.
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18. 1.5 Overview of the UNIFIED APPROACH
The Unified Approach(UA) is a methodology for software development
The UA is based on methodologies by Grady Booch, Rumbaugh & Ivar Jacobson, tries to combine the best practices, processes & guidelines along with OMG’s (Object Management Group’s) UML.
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19. 1.5 Overview of the UNIFIED APPROACH (contd….)
The heart of UA is Jacobson’s use-case.
Use case represents a typical interaction between a user and a computer system to capture the user’s goals and needs.
This book of OOSD uses a Layered Architecture(LA) to develop applications.
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20. 1.5 Overview of the UNIFIED APPROACH (contd….)
LA is an approach to software development that allows us to create objects,
that represents tangible elements of the business, independent of how they are represented to the user through an interface or physically stored in a database.
Layered Approach consists of:
View or UI (User Interfaces) Layer
Business Layer
Access Layer
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21. Goals for OOSD The software development process
Building high-quality software
Object-oriented systems development
Use-case driven systems development
Prototyping
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22. Advantages of Object-Oriented Development
Code and design reuse
Increased productivity
Ease of testing (?) and maintenance
Better understandability
Elegant design:
Loosely coupled, highly cohesive objects:
Essential for solving large problems.
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23. Advantages of Object-Oriented Development
Initially incurs higher costs
After completion of some projects reduction in cost become possible
Using well-established OO methodology and environment:
Projects can be managed with 20% -- 50% of traditional cost of development.
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24. The Journey of OOSD begins....
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