OOAD - Systems and Object Orientation Concepts

1. Systems and Object Orientation
Concepts
Dr. P.Victer Paul, Indian Institute of InformationTechnology Kottayam 1

2. Topics
 Systems Analysis and Design
 A System
 Characteristics of a system
 Elements of a System
 Types of Systems
 Software Engineering
 SDLC Model
 Programming Language
 Procedural vs. Object-Oriented
 Concepts of Object orientation
Dr. P. Victer Paul, Indian Institute of Information Technology
Kottayam 2

3. What is Systems Analysis and
Design?
 System is defined as a set of elements
arranged in an orderly manner to
accomplish an objective.
 Systems are created to solve problems.
 Systems approach in an organized way of
dealing with a problem.
 System Analysis and Design, mainly deals
with the software development activities.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 3

4. Systems Analysis and Design
 It is arranged with some logic governed
by rules, regulations, principles and
policies.
 arrangement is also influenced by the
objective the system desires to achieve.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 4

5. Defining A System
 This term is derived from a Greek word systema
which means an organized relationship among
functioning units and components.
 A collection of components that work together to
realize some objective forms a system.
 Basically there are three major components in
every system, namely input, processing and output.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 5

6. Defining A System
 All the systems operate in an environment.
 Systems Analysis: understanding and specifying in
detail what an system should do
 System Design: specifying in detail how the parts
of an system should be implemented
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 6

7.  The system can be classified based on the
predictability of its output and the degree
of information exchange with the
environment.
◦ called deterministic when the inputs, the process
and outputs are known with certainty.
◦ called probabilistic - if the output can only be
predicted in probabilistic terms
◦ A deterministic system operates in a
predictable manner while a probabilistic system
behavior is not predictable.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 7

8.  A business is also a system is also a system
where economic resources such as people,
money, material, machines, etc are transformed
by various organizational processes into goods
and services.
 A computer based information system is also a
system which is a collection of
people, hardware, software, data and
procedures that interact to provide timely
information to authorized people who need it.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 8

9. Characteristics of a system:
 organization (order),
 interaction,
 interdependence,
 integration
 central objective
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 9

10. Characteristics of a system contd..
1. Organization
• structure and order
• the arrangement of components that helps to
achieve objectives
• Example: Hierarchical organization in a company.
• Computer system: organization input devices,
output devices, CPU and storage devices
2. Interaction
• manner in which each component functions with
other components of the system
• Example: the main memory holds the data that
has to be operated by the ALU.Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 10

11. 3. Interdependence
• parts or the components of an organization or
computer system depends on one another
• the output of one subsystem is required input
for another subsystem
• Component dependence
4. Integration
• How subsystems are tied together to achieve
the system objective
• components work together within the system
even if each part performs a unique function
5. Central Objective
• Should be known in early phases of analysis
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 11

12. Elements of a System
The basic elements of the system may be listed
as:
 A system has three basic elements input,
processing and output
 The other elements include control, feedback,
boundaries, environment and interfaces.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 12

13.  INPUTS AND OUTPUTS-
 to produce an output that has value to its user
 A system feeds on input to produce output
 PROCESSOR-operational elements to convert i/p
into o/p
◦ Example: the processing of a cheque as a process.
◦ A cheque passes through several stages before it
actually gets processed and converted
 CONTROL
◦ The control element guides the system
◦ the decision-making subsystem that controls the
activities governing input, processing and output
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 13

14. • FEED BACK
• Control in a dynamic system is achieved by
feedback.
• Compares the output against a performance
standard.
• changes can result in the input or processing
and
• consequently the output Useful to improve the
system to meet the user needs.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 14

15.  ENVIRONMENT
◦ The environment is the “super system” within
which an organization operates
◦ source of external elements that strike on the
system
 BOUNDARIES AND INTERFACES
◦ Every system has defined boundaries within
which it operates. Beyond these limits the system
has to interact with the other systems.
◦ Interfaces are another important element
through which the system interacts with the
outside world
 Should be customized to the user needs.
 These should be as user friendly as possible.Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 15

16. Types of Systems
1.Physical or Abstract System
◦ Physical system: tangible entities
◦ static or dynamic in nature.
◦ Example : system-computer centre
 Desks and chairs are the static parts
 Programs, data, and applications can change
according to the user's needs.
◦ Abstract systems are conceptual.These are not
physical entities.They may be formulas,
representation or model of a real system.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 16

17. 2.Open Closed System- Majority of systems are
open systems
◦ open system has many interfaces with its
environment
◦ can also adapt to changing environmental
conditions
◦ can receive inputs from, and delivers output to the
outside of system
Closed systems: Systems that don't interact with
their environment. Closed systems exist in
concept only.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 17

18. 3.Man made Information System
◦ Information system is the basis for interaction
between the user and the analyst.
◦ an interconnected set of information resources to
manage data for particular organization
◦ Further Categorized as:
 Formal Information Systems:
 Responsible for flow of information from top
management to lower management
 information in the form of memos,
instructions, etc
 But feedback can be given from lower
authorities to top management.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 18

19.  Informal Information Systems:
 Informal systems are employee based.
 These are made to solve the day to day work
related problems.
 Computer-Based Information Systems:
 This class of systems depends on the use of
computer for managing business applications
 For example, automatic library system, railway
reservation system, banking system, etc.
 Adaptive and Non Adaptive System
 Permanent or Temporary System
 Natural and Manufactured System
 Deterministic or Probabilistic SystemDr. P. Victer Paul, Indian Institute of Information Technology Kottayam 19

20. Software Engineering
 The process of solving customers’
problems by the systematic development
and evolution of large, high-quality
software systems within cost, time and
other constraints
Requirements
Software
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 20

21. SDLC Model
 A framework that describes the activities
performed at each stage of a software
development project.
The three main phases:
◦ design
◦ build
◦ maintain
 waterfall,V-model, spiral and rapid
prototyping
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 21

22. Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 22

23. Waterfall Model
 Requirements – defines
needed information,
function, behavior,
performance and interfaces.
 Design – data structures,
software architecture,
interface representations,
algorithmic details.
 Implementation – source
code, database, user
documentation, testing.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 23

24. User Requirements
Software Requirements
Architecture Design
Detailed design & Coding
Testing
Delivery
The Waterfall
Lifecycle Workflow
Time
User Requirements Document
Software Requirements
Document
Architectural Design
Document
Detailed
Design
& Code
phase
output
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 24

25. Pros
 Easy to understand, easy to use
 Provides structure to inexperienced staff
 Milestones are well understood
 Sets requirements stability
 Good for management control (plan, staff,
track)
 Works well when quality is more
important than cost or schedule
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 25

26. Cons
 All requirements must be known upfront
 Deliverables created for each phase are
considered frozen – inhibits flexibility
 Does not reflect problem-solving nature
of software development – iterations of
phases
 Integration is one big bang at the end
 Little opportunity for customer to
preview the system (until it may be too
late)Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 26

27. The Prototyping Model
 One main idea behind prototyping is for
the development of fast prototypes and
customer availability for feedback.
 Often prototyping tools are used to help
 Developers respond to feedback and add
additional parts as application evolves into
an acceptable product.
 Recognize this process can be inserted
into the SDLC or other models.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 27

28. The Prototyping Model
REQUI REMENTS
DETERMI NATI ON
BY CUSTOMER
PROTOTYPE
DESI GM
PROTOTYPE
I MPLEMENTATI ON
SYSTEM CONVERSI ON
PROTOTYPE
EVALUATI ON
BY CUSTOMER
SYSTEM OPERATI ON
AND MAI NTENANCE
REQUI REMENTS FOR
CORRECTI ONS, CHANGES
AND ADDI TI ONS
REQUI REMENTS
FULFI LLED ?
SYSTEM TESTS AND
ACCEPTANCE TESTS
NO
YES
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 28

29. Risk Reduction
Iterative
T I M E
Iteration Iteration Iteration Iteration Iteration
Risk reduction
R
I
S
K
Waterfall risk
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 29

30. Best Practices of Software
Engineering
Develop Iteratively
Control Changes
Manage
Requirements
Model
Visually
Verify
Quality
Use
Component
Architectures
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 30

31. Programming Language
 A programming language is a computer language
programmers use to develop applications
 set of instructions for a computer to perform
specific tasks.
 The commonly used programming methodologies
are:
◦ Procedure-oriented programming
◦ Object-oriented programming (OOP)
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 31

32. Procedure-oriented programming
 Involves dividing a large program into a set of sub-
procedures or subprograms that perform specific
tasks.
 Module consists of single or multiple procedures.
 Most of the data is shared as global that can be
accessed from anywhere within the program.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 32

33. Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 33

34. an approach that provides a way of modularizing
programs by creating partitioned memory area for
both data and functions that can be used as
template for creating copies of such modules on
demand.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 34

35. Procedural vs. Object-Oriented
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 35

36. Procedural vs. Object-Oriented
S. No Procedural Programming Object-Oriented Programming
1 Emphasis on Procedures Emphasis on Objects/Data
2 Data is not hidden Data is hidden
3 Data and methods are
separate
Data and methods are combined
using objects
4 Data can be accessed by
external functions
Data cannot be accessed by
external functions
5 Top-down Approach in
program design
Bottom-up Approach in program
design
6 Eg. C, PASCAL Eg. C++, JAVA, Smalltalk
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 36

37. Fundamental concepts of object
oriented world
 Objects: Objects represent an entity and are the basic building
block.
 Class: Class is the blue print of an object.
 Abstraction: Abstraction represents displaying only essential
information and hiding the details
 Encapsulation: Encapsulation is the mechanism of binding the
data together and hiding them from outside world.
 Inheritance: Inheritance is the mechanism of making new
classes from existing one.
 Polymorphism: It defines the mechanism to exists in different
forms.
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 37

38. The End…
Dr. P. Victer Paul, Indian Institute of Information Technology Kottayam 38