Chapter – 2
SDLC (System Development Life Cycle)
Definition of SDLC: It is an organizational process of developing and maintaining the system. It establish a system
project plan because it gives overall list of process and sub process required for developing
system. It includes various phases.
Phases / Stages in SDLC: 1.
2.
3.
4.
5.
6.
7.
8.
9.
Preliminary investigation / Problem definition / Recoganization of need
Feasibility study
System analysis
System design
System coding
System testing
Implementation
Post implementation
Maintenance
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Organization Based
Source of system
ideas
Govt. Rules &
Regulations
Organization
Top
management
System
for
Change
Consumer
Union
User
Recoganization of need
System
analyst
Environment Based
User
Feasibility Study
System Analysis
System Design
System Coding
System Testing
Implementation
Post Implementation
Maintenance
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Phase – 1
Preliminary Investigation: 

It is an introductory step in SDLC the request made by the user can be the request for
changing or improving the existing system.
Sub stages involved in system investigation are defining the problem or Recoganization
of need.
Problem definition: 


Here the problem is defined by developing alternative system. System analyst (SA) help
is taken for defining and resolving the problem the system analyst identifying the
problem and prepare the written document, consistency of the object and scope of the
problem.
Problem is defined on the basis of interview or the meeting with the user. After the
problem is defined, the written statement of the problem is sent to the user and the
user give the response to these statements.
Depending upon the user response the problem is defined
 System problem may occurs because of the following reasons: 1. The existing system is working slowly.
2. The existing system unable to manage the workload.
3. The existing system may not be cost effective.
4. The existing system is not correct.
5. There are some security problems in the investigation system.
Requirement specification: 
It is the part of problem definition. This activity consists of first gathering the
requirements and analyses those gathered requirements. The customer requirements
are identified and documented in SRS document (Software/ System Requirement
Specification). SRS document have three basic contents are: -
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1. Functional Requirement
2. Non – Functional Requirement
3. Goals of Implementation

SRS document act as a contract b/w the user (customer) and development team. So, the
main purpose of requirement analysis to analyze the collected information So as to
obtain a clear understanding of the product to be development, with a review of
removing all the ambiguities and in completeness from the initial customer specified
requirements. Here the following questions are answered: -
1.
2.
3.
4.
What is the problem?
What is it important to solve the problem?
What are the data input to the system and what are the data output?
What will be the procedure to be followed?
Functional requirements: Here the input data is specified with its format, some is done for the output data.
Non – Functional Requirements: It includes the issues like timing of the projects, reliability, portability, security and usability.
Goals of the Implementation: There are notes which can be taken as a help by the developer for the suggestion. It includes
issue like revision of the system, enhancement of the system, new devices to be supported in
the future and reusability issues.
Characteristics of good SRS documents are: 




Concise
Structured
Black – Box view
Verifiable
Traceable
Characteristics of bad SRS document: 


Over specification
Forward references
Irrelevant information
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Initial Investigation tools / System Investigation tools: System investigations are various strategies for required determination and system
investigation data is gather through four methods: 1.
2.
3.
4.
Review the organizational documents
Interviews
On – Site observation
Questionnaires
Review the organizational documents: 



It is important for system analyst to know about the organization before starting the
projects.
It is required to know the operation and the management of the organization.
This can be suited by organizational charts and written procedures of the organization.
The Procedures describe the way in which process of the organization operates.
Interviews: 

The written procedure does not provide the system analyst the actual information in
which the users are using for current operations.
These are conducted by the analyst which provide the better understanding of the
project.
On – site Observation: 


In this method the analyst observe the activities of the system directly.
During the phase the analyst on the office environment, workload of the users
(worker’s).
The method of the work and services provided by the organization.
Questionnaires: 
It is a tool which has a question to which the individuals have to respond and it is
distributed to the group of users and depending upon their response the report is
generated.
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Phase – 2
Feasibility study: 


Feasibility study is a test of proposal according to its impact in the organization, ability
to meet the user needs and effective resources. Here few major questions are being
focused : 1. What are the user’s needs and how does the candidate system meet those
needs?
2. What resources are available for the candidate system?
3. What will be the impact of candidate system of the organization?
Feasibility study includes investigation, evaluation of the problem, identification and
description of the candidate system, specification and performance of the candidate
system, cost of the system and final selection of the best system.
Feasibility study does not solve the problem it just find the scope of the system. It
generates a formal document which includes: 1. Problem statement
2. Summary of findings
3. Details of finding
4. Conclusion / recommendation
Types of the Feasibility study: 1.
2.
3.
4.
5.
6.
Organizational and Behavioral Feasibility Study
Legal Feasibility Study
Economical Feasibility Study
Technical Feasibility Study
Schedule Feasibility Study
Operational Feasibility Study
Organizational and Behavioral Feasibility Study: 


It depicts or describes the feasibility study in terms of organization and behaviors of the
employee’s.
It Depicts that for the purposed system
The organization includes the team work, peace and no discrimination among the
employee’s.
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Legal Feasibility Study: 
It verifies that weather the purposed system is according to the rules and regulations of
the management or government.
Economical Feasibility Study: 

Here cost and benefits are evaluated.
It includes the employee cost, the production cost and finally concludes that weather
the return justifies the investment or not.
Technical Feasibility Study: 

The major concern is to observed weather the reliable hardware and software of the
organization meets the need of the purposed system or not
It includes the hardware and software required its reliability and its security.
Schedule Feasibility Study: 
Weather the system finishes its task with in a provided time for the development or not.
Operational Feasibility Study: 
It teases with the operations of management, employees, customers and the service
provider involves in the project. It include the questions like: 1. Where the implementation is done smoothly?
2. Will the existing business methods be acceptable to the user or not?
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Phase – 3
System Analysis: 


It involves the detailed study of the current system leading the specification of new
system.
Interviews and questionnaires are to be done are: 1. Specification of what the new system will complete based upon the
requirements.
2. The functional hierarchy shows the function to be performed by the system and
relationship with each other.
3. List of the attributes of the entities is documented so as to keep the record.
Various tools used by system analyst are:  Review the organizational documents
 Interviews
 On – Site observation
 Questionnaires
Phase – 4
System Design: 


System design is based upon the user requirement and the detailed analysis of the new
system.
The purposed or new system is designed the previous phases focus on what the system
will do? But this phase totally focuses on how the system will do?
Various types of design are: 1. Interface Design
2. Data Design
3. Process Design
4. Detailed System Design
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Phase – 5
System Coding: 


It is also called programming phase.
It is an important stage in which we convert whole design of the system in computer
understandable language.
This helps in fast development, maintenance and future change, if required.
Phase – 6
System Testing: 

After the coding o the whole system a test run of the system is done for removing all
the bugs.
It is an important phase of an successful system. There are two test runs: 1. Unit test
2. System test
Phase – 7
Implementation: 

It is the stage of a project during which theory id turned into practice.
All program of the system loaded to the user’s computer after the system training of the
user’s starts.
Phase – 8 and 9
Post – Implementation and Maintenance: 


With the passage of time, the system tends to get old.
Hence, it requires updating according to the organizational changes.
It is known as the system implementation.
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