Introduction to Object Orientation.

1. T.Y.B.Sc.(Comp. Sci.) Sem. I
Object Oriented Software Engineering
(OOSE)
CS-336
Faculty
Dr. Amit D. Kasliwal
Asst. Professor

2. Chapter 1
Object Oriented Concepts and Principles
 The Software Engineering is a systematic approach to the design,
development, operation and maintenance of a software.
 Series of processes, if followed can lead to development of a software.
 Based on functions or procedures with limited reusability of
programming structure.
 And sometimes also referred to as Traditional Software engineering.
 The size and complexity of software is increasing day by day.
 And traditional software engineering may not be effectively applicable.
 So we want to simplify the development process and to produce high
quality maintainable software to fulfill user requirements.

3. What is Object Orientation ?
 Object Orientation is viewing and modeling the real world entities as a
collection of interacting and interrelated objects.
 An object is a real world entity or element in an object oriented
environment that encapsulates (combine) data and the functionalities
to model real world.
 Object may have a physical or a conceptual existence such a,
 That distinguishes it from other objects.
 That determines the characteristic or properties as well as the values
of the properties that the object holds.
 That represents externally visible activities performed by an object
in terms of changes in its state.
 Objects can be modeled according to the needs of the application.

4.  In Object oriented environment, the software is developed by building
self modeled objects that can be easily replaced and reused.
 Object orientation encourage the world to view a software as a
cooperative and collaborating objects.
 An object is an entity that save it’s state (data) and offers several
methods (behaviors) to either examine or affect this states.
What is Object Orientation ?

5.  A Class represents a collection of objects having same characteristic or
properties that follows common behavior.
 Blueprint or description of the objects that can be created from it.
 Creation of an object as a part (member ) of a class is called instantiation.
That is “object is an instance of a class.”
 A set of objects with similar behavior & data/information may constitute
a class.
 In general, different objects of a class have some difference in the values
of the attributes.(and attributes are often referred as class data)
 A set of methods refers the behavior of the objects of the class.
 Let us consider a class named Book, with attribute subjectdescriptor ,
ISBN, booktitle , language, authorname , publisher and so on. Some of
its operations like addbook(), deletebook(), updatebook() & viewbook().
What is Object Orientation ?

6. What is Object Orientation ?

7.  So we can say, object orientation relies on two aspects i.e. Information
and Behavior.
 Information has a unique identity.
 It has a description of its structure used to create it.
 And has state to represent its current condition.
 Behavior is to answers the questions like,
 What can an object do?
 What we can do with the object?
 How a object can be use?
What is Object Orientation ?

8.  In Object orientation approach, encapsulation, polymorphism and
inheritance concepts as used.
 Encapsulation is the process of hiding information by combining the
data and operations.
 It allows to access the data only through the that operations which are
designed to operate on the data.
 Its keeps data safe and secure from external interventions.
What is Object Orientation ?

9.  Polymorphism is originally a Greek word that means the ability to take
multiple forms. The dictionary meaning is “many forms”.
 In object oriented, polymorphism implies using operations in different
ways, depending upon the instance they are operating upon.
 Like in the real world, the same operations may have different
meanings in different situations.
 Same data is sent to different objects irrespective of their class, but the
responses of objects may be different.
 Polymorphism allows objects with different internal structures to have
a common external interface.
 Polymorphism is particularly effective while implementing inheritance.
What is Object Orientation ?

10.  In object orientation, Inheritance allows creating new classes from
existing classes by extending and refining its capabilities.
 The existing classes are called the base / parent / super classes, and the
new classes are called the derived / child / sub classes.
 The subclass can inherit or derive the attributes and methods of the
super class /classes provided that the super-class allows so.
 Beside this, the subclass may add its own attributes and methods and
may modify any of the super-class methods.
 Following are the inheritance type.
 Single Inheritance Multiple Inheritance
 Multilevel Inheritance Hierarchical Inheritance
 Hybrid Inheritance
What is Object Orientation ?

11. What is Object Orientation ?

12. Object Oriented System Development
 In order to develop a system / software, a systematic approach should be
adopted satisfying two viewpoint, Internal and External
 In Internal viewpoint, everything about the software (from the developer
view) has to be maintain so that it can be easily modify, extend & reuse.
 With External viewpoint (From the user view), it has to be accurate in
result generation, reliable and easy to learn and adopt.
 And thus to satisfy the individual's viewpoint the , A use case driven
approach (Considering Object Orientation in the center) of software
engineering was prepared referred as Object Oriented Software
Development(OOSD) having SDLC consisting of three phases.
 Object Oriented analysis (OOA), Object Oriented Design (OOD) and
Object Oriented Construction (OOC)

13. Object Oriented System Development

14.  Object Oriented Analysis in OOSD concerned with determining the
system requirement, identifying classes and relationships between
classes in the required domain.
 OOA also identifies users (actors) and how they use the software.
 It always consider the scenario to help the analyst to understand the
requirements as mentioned by the end user.
 According the Ivor Jacobson, OOA works with use case diagram to
understand the scenario to describe end user’s interaction with
software.
 It helps in determining who does what in the interaction among objects
and what role end users plays by using their relationship.
 OOA supports collaboration that describes the interaction among
objects to achieve given goal.
Object Oriented Analysis

15.  In OOA, three analysis techniques Object modeling, Dynamic
modeling, and functional modeling are used.
 Object Modeling develops the static structure of the software in terms
of objects.
 It identifies the objects, the classes into which the objects can be
grouped into and the relationships between the objects.
 It also identifies the main attributes & operations of each class.
 It can be visualized in the following steps −
 Identify objects and group into classes and their relationships
 Define user object attributes
 Define the operations that should be performed on the classes
 Review glossary
Object Oriented Analysis

16.  Functional Modeling is the final component of OOA.
 It shows the processes that are performed within an object and how the
data changes as object moves between methods.
 It specifies the meaning of the operations of object modeling and the
actions of dynamic modeling.
 It corresponds to the data flow diagram of traditional analysis process.
 It has the following steps −
 Identify all the inputs and outputs
 Construct data flow diagrams showing functional dependencies
 State the purpose of each function
 Identify constraints
 Specify optimization criteria
Object Oriented Analysis

17.  In Dynamic Modeling, software’s behavior with respect to time and
external changes are prepared after the static behavior is analyzed.
 It is a way of describing how an individual object responds to events,
either internal events triggered by other objects, or external events
triggered by the outside world.
 It has following steps −
 Identify states of each object
 Identify events and analyze the applicability of actions
 Construct dynamic model diagram, comprising of state transition
diagrams
 Express each state in terms of object attributes
 Validate the state–transition diagrams drawn
Object Oriented Analysis

18.  The analysis model is not sufficiently formal but still we follows the
OOA to develop a software.
 Constructed software must be adapted to the implementation
environment such that it validate the analysis result.
 OOC phase use to identify the implementation environment.
 It helps in identifying and investigating the consequences that the
implementation environment will have after design.
 It incorporate conclusions and develop a first approach of a design
model.
 OOC uses process combining sub processes of designing, building
Model.
 It redefine the analysis model in the light of the actual implementation.
Object Oriented Construction

19.  In OOC, designing model decide how different issues such as DBMS,
programming language features, and distribution will be handled.
 It compose of blocks of code which are specific to class.
 In the Building model of OOC, developers attempt to implement
analysis model using programming language.
 It is used obtain a clear traceability to the analysis model.
 It works for final structure that should reflect how the implementation
environment has affected construction.
 E.g. if the programming language does not support inheritance, the
model must reflect how the inheritance is really implemented.
Object Oriented Construction

20. Development

21. Identifying the Classes and Object
 When we look around the problem of a software application, the objects
may be more difficult to comprehend.
 We can identify objects by examining the problem statement given for
the software with performing grammatical parse.
 Objects are determined by underlining each noun or noun clause and
entering it in a simple table. Also synonyms should be noted.
 If the object is required to implement a solution, then it is part of the
solution space.
 Objects can be External entities (e.g., other systems, devices, people) ,
Things (e.g., reports, displays, letters, signals), Occurrences or events
(e.g., a property transfer or the completion of a series of robot
movements), Roles (e.g., manager, engineer, salesperson), Organizational
units (e.g., division, group, team), Places (e.g., manufacturing floor or
loading dock) or Structures (e.g., sensors, four-wheeled vehicles, or
computers).

22.  The analysis process starts with the identification of a set of conceptual
classes – the categories of things which are of significance in the system
domain. A good understanding of the system domain is important.
 A class in a model is thing that represents a category of real-world entities
from the system domain.
 Although these may be tangible real world things, they may also be
intangible things such as events, roles and organizational units.
 The software developer often gains this through discussion with user.
 Possible classes for inclusion may thus emerge during the course of the
requirements process.
 However, there are a number of other techniques that you can use to help
identify appropriate classes from a requirements document.
 Inappropriately chosen classes may add complexity to later phases of the
development and could make the software difficult to maintain and/or
extend.
Identifying the Classes and Object

23. Classes and Object

24. Specifying the Attributes (With Visibility)
 Attributes describe an object that has been selected for inclusion in the
analysis model.
 It is the attributes that define the object clarifying what is meant by the
object in the context of the domain.
 To specify a meaningful set of attributes for an object, the analyst can
again study the requirement for the problem and select those things
that reasonably "belong" to the object.
 In addition, it must be the answered of the question "What data items
define this object in the context of the problem?"
 Each of the data items in the block could be
further defined to an elementary level, but
for our purposes, they constitute a reasonable
list of attributes for an object .

25. Defining Operations
 Operations define the behavior of an object and change the object’s
attributes in some way.
 Specifically, an operation changes one or more attribute values that are
contained within the object.
 Therefore, an operation must have knowledge of the nature of the
object's attributes
 It must be implemented in a manner that enables to manipulate the
data structures that have been derived from the attributes.
 Although many different types of operations exist, they can generally
be divided into three broad categories:
 operations that manipulate data in some way (e.g., adding, deleting,
reformatting, selecting),
 operations that perform a computation,
 operations that monitor an object for the occurrence of a controlling
event.

26. Finalizing the Object Definition
 The definition of operations is the last step in completing the
specification of an object.
 Operations were picked from a grammatical parse of the processing
narrative for the system.
 Additional operations may be determined by considering the "life
history" of an object and the messages that are passed among objects
defined for the system.
 The generic life history of an object can be defined by recognizing that
the object must be created, modified, manipulated or read in other
ways, and possibly deleted.