System analysis and design

System Analysis & Design
Unit 1: System Concepts and the
Information Systems Environment

Introduction to The System Concept
A System is a way of thinking about organizations
and their problems.
It also involves a set of techniques that helps in
solving problems.

Definition
The term system is derived from the Greek word
‘systema’, which means an organized relationship
among functioning units or components.
“A system is an orderly grouping of interdependent
components linked together according to a plan to
achieve a specific objective.”

Characteristics of a system
1. Organization
2. Interaction
3. Interdependent
4. Integration
5. Central Objective

1. Organization
• Organization implies structure and
order.
• It is the arrangement of component
that helps to achieve objectives.
For example:-
In the business
system, the hierarchical relationship
starting with the president on top and
leading downward to the worker
represent to organization structure.
Vice President
Sales
Vice President
Production
Vice President
Accounting
President
Workers Workers
Organization
Structure

2. Interaction
“Interaction refers to the manner in which
each component functions with other
components of the system.”
For example:-
In a computer system, the
central processing unit must interact with
input device to solve a problem.
• Purchasing must interact with production.
• Advertising with sales.
• Payroll with personnel.
Input OutputCPU
Data Information
Interaction

3. Interdependent
Interdependent means that part of the organization or computer system
depend on one another.
They are coordinated and linked together according to a plan.
One subsystem depends on the input of another subsystem for proper
functioning.
“That is, the output of one subsystem is the required input for another
subsystem.”

4. Integration
Integration refers to the holism of systems.
Integration is concerned with how a system components are
coordinated and linked together within the system even if
each part performs a unique function.

5. Central Objective
This is the last characteristics of a system.
Object may be real or stated.
All the components work together to achieve that particular
objective.
The important point is that user must know the central
objective of a computer application early in the analysis for a
successful design and conversion.

Elements of a System
There are six elements given below:-
• Input and Output
• Processor
• Control
• Boundaries and interface
• Environment
• Feedback

1. Input and Output
Inputs and the elements (such as material, human
resources, information) that enter into the system for
processing.
Output is the outcome of processing.
The main aim of the system is to produce an output which
is useful for its user.

2. Processor
The processor is the element of a system that
involves the actual transformation of input into output.
It is the operational component of a system.
Process may modify the input totally or partially,
depending on the specifications of the output.

3. Control
The control element guides the system.
It is the decision-making subsystem that control the
pattern of activities governing input, processing and
output.
The behaviour of a computer system is controlled by
operating system and software (applications).

4. Boundaries and Interface
Boundaries are the limits that identify its components,
processes and interrelationship when it interfaces
with another system.
Each system has boundaries that determine its
sphere of influence and control.

5. Environment
Environment is the source of external elements that
affects the system.
It determines how a system must function .
For example:-
Vendors and competitors of organization’s
environment, may provide constraints that affect the
actual performance of the business.

6. Feedback
Feedback provides that control in a dynamic system.
It indicates how well a system is performing.
It is helpful for modify the system according to that
need.
It provide to system how you make your system
effective than other in the bases of customer choice.

Types of System
1. Physical or Abstract Systems
2. Open or Closed Systems
3. Adaptive and Non Adaptive System
4. Permanent or Temporary System
5. Natural and Manufactured System
6. Deterministic or Probabilistic System
7. Social, Human-Machine, Machine System
8. Man-Made Information Systems

1. Physical or Abstract Systems
a. Physical Systems:-
We can touch and feel them, it is physical and real
entities.
For example:-
Computer, College and Hotel etc.
b. Abstract Systems:-
These are non-physical or conceptual entities.
For example:-
Formulas, representation or model of a real system.

a. Open System:-
An open system must interact with its
environment. It receives inputs from and delivers outputs
to the outside of the system.
For example:-
an information system which must adapt
to the changing environmental conditions, college and
bank.

b. Closed System:-
Do not interact with its environment.
Neither receives input from nor delivers outputs to the
outside.

a. Adaptive:-
Adaptive system responds to the change in
the environment in a way to improve their performance
and to survive.
For example:
Human beings and animals.

b. Non Adaptive:-
Non Adaptive System is the system which
does not respond to the environment.
For example:
Machines.

a. Permanent System:-
Permanent System persists for long time.
For example:
Business policies.

b. Temporary System:-
Temporary System is made for specified time
and after that they are destroy.
For example:
A DJ system is set up for a program and it is
dissembled after the program.

a. Natural System:-
Natural Systems are created by the nature.
For example:
Solar System, seasonal system.

b. Manufactured System:-
Manufactured System is the man-made
system.
For example:
Rockets, dams and trains.

a. Deterministic System:-
Operates in a predefined or known manner.
No uncertainty involves.
Deterministic System operates in a predictable manner
and the interaction between system components is
known with certainty.
For example:
A Computer Programme, H2O.

b. Probabilistic System:-
Probabilistic system shows uncertain
behaviour. The exact output is not known.
uncertainty involves.
For example:
Weather forecasting and mail delivery.

7. Social, Human-Machine and Machine System
a. Social System:-
Social System is made up of people.
For example:
Social clubs and societies.

b. Human-Machine System:-
In Human-Machine System, both human and
machine are involved to perform a particular task.
For example:
Computer Programming.

c. Machine System:-
Machine System is where human interference
is neglected. All the tasks are performed by the machine
For example:
An autonomous robot.

8. Man-Made Information System
It is an interconnected set of information resources to manage
data for particular organization, under Direct Management Control
(DMC)
This system includes hardware, software, communication, data,
and application for producing information according to the need of
an organization.
Information reduce uncertainty about an event or situation.

Man-Made information systems are divided into three types-
1. Formal Information System:-
It is based on the flow of information in the form of memos,
instructions, etc., from top level to lower levels of management.
For example:-
Business Chart- (Each person have their specific work)

2. Informal Information System:-
This is employee based system which solves the day to
day work related problems.
For example:-
Casual conversation, exchange of news on topic related to
work, messaging on social media or blogs, conversation on
coffee or lunch etc.

3. Computer Based Information System:-
This system is directly dependent on the computer for
managing business applications.
It uses computer to process data and produce information.
For example:-
Automatic library system, railway reservation system and
banking system etc.

System Development Life Cycle (SDLC)
SDLC is a framework that describe the activities performed at each stage of a software develop
project.
The business functions, each of these information systems has a particular purpose or focus and
each has a life of its own.
This life of its own concept is called the system development life cycle on (SDLC) and it includes the
entire process of planning, building, deploying using updating and maintaining an information system.
The development of a new information. System involves several different. But related activity, these
activities or phases usually include, planning, analysis, design implementation and maintenance
support.
In other word SDLC is a conceptual model that guides project management in information system
deployment.
It is a well-defined process by which a system is develop and implements.

Phases of SDLC PLANNING: Obtain approval for
project, initiate, Assess
Feasibility, plan, schedule
ANALYSIS: Understand business
needs and processing needs
DESIGN: Define solution system
based on requirement and
analysis decision
IMPLIMENTATION: Construct,
test, train users, install new
system
MAINTENANCE: Keep system
healthy and improve

Need for new system
Preliminary
Investigation
Feasibility Study
System Analysis
Development
System Design
System Testing
Implimentation
Evalution
Maintainence
Maintainence

There are following activities involves in SDLC
• Preliminary Investigation (Problem Identification)
• Feasibility Study
• System analysis
• System analysis
• System designing
• Development of software
• System testing
• Implementation & Evaluation
• Maintenance

1. Preliminary Investigation (Problem Identification)
One of most difficult task of the system analyst is identifying the real problem of
the existing system.
It defines the user requirements or what the user expects from the new system. This also
includes the rough idea of the resource requirements as well as estimated time for
completion and number of persons expected to be involve in each phase.
Problem identification helps in:-
• Defining a problem
• Setting proper system goal
• Determining the boundaries of the project by considering the limitations of available
resources.

1. Feasibility study
It determine to possibility of either improving the existing system or developing the
complete new system. It helps to obtain an overview of the problem and to get rough
assessment of whether physical solution exist. The purpose of feasibility study is to
determine whether the requested system successfully realizable.
There are four aspects of feasibility study:-
• Technical feasibility.
• Economical feasibility
• Operational feasibility
• Behavioural feasibility

a. Technically Feasibility
It involves the required and existing computer system, hardware,
software & to what extent it can support the proposed application.
It answers following questions:-
Q1. Whether the system can be carried out with existing equipment ?
Q2. Whether the existing software is enough ?
Q3. If a new technology is required how best it can be implemented ?
Q4. Is reliable technology and training available ?

b. Economic Feasibility
It involves cost benefit analysis to determine the benefit and saving that
are expected from new system and compared with costs. It benefits out weight
cost then decision is made to design and implement new system.
Q1. Do benefit justify costs?

c. Operational Feasibility
It concerns with human, organisational and political aspects. It covers
technical performance as well as acceptance within the organisation. It
determines the general attitude and job skills of existing personals and
whether any restructuring of jobs will be acceptable to the current user.
Q1. Will the managers and users support it ?

d. Behavioural Feasibility
It includes how strong the reaction of staff will be towards the
development of new system that involves computer’s use in their daily work.
So resistant to change is identified.

2. Feasibility Study
Results:-
• Problem is clearly stated.
• Feasibility report is created.
Management Recommend Top Alternative based upon:-
a. System fit into the Organization.
b. Flexibility for the future.
c. Cost vs. benefits.

3. System Analysis
1. What must be done to solve the problem?
2. Detailed study of various operations performed by the system.
3. Define the boundaries of the candidate system.
4. Data collection or Data gathering logical model.
Tools:-
1. Data Flow Diagrams
2. Interviews
3. On-site observations [Show Working]
4. Questionnaires.
5. Data Dictionaries.

3. System Analysis
Software Requirement Specification documents [(SRS)
document] is finalized which includes-
1. Functional or non-function requirement.
2. What the system will do and what it is not expected to do.
3. Information about other system with which system must interface.

4. Design
The most creative and challenging phase of the system life cycle is system design.
The term design describes a final system and the process by which it is developed.
Translates the performance requirements into design specifications.
Task:-
• How should the problem be solved?
• Input data and master file are designed.
• Output formats are designed.
The final report prior to the implementation phase includes-
• Procedural Flowcharts
• Record Layout
• Report Layout
• Implementing plan (Working plan)

Output
Design
1
Input
Design
File
Design
Processing
Design
Detailed
System
Documentation
Design
Submitted to
Management
For approval
Test Programs
Design
Accepted ?
Abandon
Project
2
Cost justification
and system
design
Yes
No
Go to
implementation

5. System Coding & Testing
Coding:-
It is the phase, where details design is used to actually construct and built the
system software.
Programmers are also responsible for documenting the program, documenting the program,
document should include comments that provide explanation of the procedure code in the
program.
Task:-
• Build the system to the design specifications.
• Develop the software.
• Acquire the hardware.

5. System Coding & Testing
Testing:-
System testing is a process of making sure that the program
performs for intended (desired) task.
Test the system for acceptance:-
• Program Testing (Unit testing).
• String Testing.
• System Testing.
• User acceptance testing.

6. Implementation
The implementation phase is less creative than system design.
Implementation is the final phase of the system. It consists of installing hardware, programs,
collection of data and organization problem to interact with at run the system.
In the implementing phase, user actually start using the system. This phase also involve
training the user for using the system and also providing them friendly documentation.
Once the system is implemented. It should be evolution.
Evolution is the process by verifying the capability of the system.
After it is put an operation to see weather it is fulfil the objective or not evolution is an important
aspect.

6. Implementation
Task:-
• Convert from old system to new system.
• Train users
• Compile final documentation
• Evaluate the new system
Type of Conversions:-
• Direct / Plug / Crash approach - (Overwrite System)
• Parallel approach
• Pilot approach – (one group with in the business)
• Phases / incremental approach – (Individual Part)

6. Post – implementation and Maintenance
After the installation phase (Implementation phase) is completed, the evolution and maintenance
process will start, like any other system, there is an again process the requires periodic
maintenance of hardware and software.
Should the system be modified.
Type of Maintenance:-
• Correction of new bugs found (corrective)
• System adjustments to environmental changes and user’s changing needs
(adaptive). – Add new functions
• Enhancing the performance, changes to use better techniques
when they become available (perfective).

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System analysis and design

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