Some Basic Concepts of Object Oriented Methodology

Friday, January 23, 2015 1
Presented By
Manoj Kumar
Object Oriented Methodology

 It is a new way of thinking about problems using models based
on real world concepts.
 The basic construct is object which combines both data
structure and behavior in a single entity.
 Rambaugh presents an object oriented software development
methodology, the Object Modeling Technique (OMT) which
extends from analysis through design to implementation.

 Analysis model is built to abstract essential aspects of application
domain which contains objects found in application, their properties
and behavior.
Then design model is made to describe and optimize the
implementation.
Finally, the design model is implemented in a programming
language, database or hardware.
 Graphical notation is used for expressing object-oriented models.
Continue…

What is Object-Oriented?
 Software is organized as a collection of discrete objects that incorporate
both data structure and behavior.
In general, it includes - identity, classification, polymorphism and
inheritance.
Object Oriented Programming Language =
Object Based Programming Language + Inheritance + Dynamic Binding

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Object-Oriented Development?
 The theme is the identification and organization of application
concepts rather than final representation in a prog. Language.
 OOD approach encourages software developers to work and
think in terms of the application domain through most of the
software engineering life cycle.
 It is a conceptual process independent of a programming
language until the final stage

Object-Oriented Methodology
Four phases of OMT (can be performed iteratively)
Analysis: Objects, dynamic and functional models
System Design: Basic architecture of the system.
Object Design: Static, dynamic and functional models of objects.
Implementation: Reusable, extendible and robust code.

Object-Oriented Models
A model is an abstraction of something for the purpose of
understanding it before building it.
There are three models,
 Object model
 Dynamic model
Functional model

Object Model
 Describes basic structure of objects and their relationship.
 Contains object diagram.
 Object diagram is a graph whose nodes are object classes
(Classes) and whose arcs are relationships among classes.

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Dynamic Model
 Describes the aspects of a system that change over time.
 It specifies and implement control aspects of a system.
 Contains state diagram.
 State diagram is a graph whose nodes are states and
whose arcs are data-flows.

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Functional Model
 Describes data value transformation within a system.
 Contains data flow diagram.
 Data Flow Diagram is a graph whose nodes are
processes and whose arcs are data flows.

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Dynamic Modeling
 First examine the system at a single moment of time.
 Then examine changes to objects and their relationships over time.
 Those aspects of a system that are concerned with time and changes
are dynamic model, in contrast with static or object model.
 Control is the aspect of a system that describes the sequences of
operations that occur in response to external stimuli without
considering what the operation do, what they operate on, and how
they are implemented.

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Events
 It is something that happens at a point in time
One event may logically precede or follow another or the two events
may be unrelated.
The two events are causally related.
The two events are causally unrelated are said to be concurrent i.e.
they have no effect on each other.
In modeling a system we do not establish an ordering between
concurrent events because they can occur at any order

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Continue…
An event is a one-way transmission of information from one
object to another.
In real world, all objects exist concurrently.
An object sending an event to another object may expect a
reply but the reply is a separate event under the control of
the second object which may or may not choose to send it.
Every event is a unique occurrence, but we group them into
event classes and give each event class a name to indicate
common structure and behavior.

A scenario is a sequence of events that occurs during one particular
execution of a system.
The scope of a scenario can vary; it may include all events in the
system or it may include only those events generated by certain
objects in the system.
It can be the historical record of executing a system or a thought
experiment of executing a proposed system.
An event trace extends the scenario to clarify events between objects
Scenario & Event-Trace

It is an abstraction of the attribute values and links of an object.
Set of values are grouped together into a state according to
properties that affect the gross behavior of the object e.g. the state
of bank is either solvent or insolvent whether its assets are greater
than liabilities.
 A state specifies the response of the object to input events.
Response is same for all values within the same state and may
be different for values in different states
Response of an object to an event may include an action or
change of states by the object.
States

 State diagram is a graph whose nodes are states and whose directed
arcs are transitions labeled by event names.
A state diagram describes the behavior of a single class.
Since all instances of a class have same behavior they all share the
same state diagram as they all share the same class features.
But as each object has its own attribute values so each object has its
own state.
Each object is independent of the other objects and proceeds as its
own pace.
State Diagram

State Diagram Banking
System

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Some Basic Concepts of Object Oriented Methodology

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