Object Oriented Concepts
Introduction
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Agenda
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Design, Software design
Definitions of OO constructs
Class Diagrams, Sequence Diagrams, State
Diagrams
Some principles of design
Case Study
Back To OO
OO in maintenance projects
What it is not!
– It is not a UML session
– Less syntax specific, more conceptual
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Modeling
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a small scale replica of the system
a simplification of reality
Uses
– Communication with clients
– Visualization of the system
– Discussion of strengths and weaknesses of proposed
system before implementation
– Provides the big picture
– Handling complexity by providing different views of
thesystem
– Documents the tradeoffs that we make
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Abstraction
The selective examination of part of the
system
 The amplification of the relevant and
elimination of the irrelevant
 Technique for dealing with complexity
 Different applications will abstract
different aspects of an object
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Constructs
Classes
 Objects
 Relationships
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– Association
– Aggregation
– Inheritance
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Polymorphism
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Use cases
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Used in analysis phase
Describes an interaction of one or more users
with the system
Simple Use case diagram depicts the interaction
in a graphical format
Complex use case diagrams depict actors, system
boundary, and use cases of a system. They also
depict the relationship between use cases
A use case can use another use case
A use case can extend another use case
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Simple use case – item
checkout
Customer sets item on counter
 Sales clerk swipes bar code reader on item
code
 System looks up UPC code
 System shows item code and price
 System adds price to bill amount
 Error code 1 : item code unreadable
 Error code 2: item code not found
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Case Study
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Problem statement
– Must be in users language
– Can involve UML diagrams for analysis
– Analysis may lead to restatement of problem as issues
become more clear
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Use Cases
Class diagram
Sequence Diagram
State Diagram
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Back to OO – Some principles
Abstraction
 Open closed principle
 Single responsibility principle
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Back to OO
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Benefits
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Abstraction
Encapsulation
Communication
Different views of the same system
Same terminology from requirements to
implementation
– Loosely coupled systems
– Cleaner interfaces between systems
– Reuse????????
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OO in maintenance projects
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Agile methods – Extreme Programming
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Standup meetings
Pair programming
Client involvement
Small frequent releases
Use Cases
Continuous Refactoring and testing
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Summary
Basic concepts covered using a
programming language
 Case study
 Benefits/drawbacks of OO
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OO Tools
ArgoUML
 Poseidon
 Together C
 Rational Rose
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References
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Books
– Object oriented Modelling and Design – Rumbaugh
– UML User guide – Booch, Rumbaugh, Jacobson
– UML distilled – Martin Fowler
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URLs
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www.martinfowler.com
www.holub.com
www.omg.org, www.uml.org
http://www.intelligentedu.com/newly_researched_free
_training/UML.html
– www.objectmentor.com
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