Date post: | 14-Apr-2018 |
Category: |
Documents |
Upload: | sameer-khan |
View: | 214 times |
Download: | 0 times |
of 25
7/30/2019 W-4 the System Development Life Cycle (1) sameer
1/25
System Analysis & Design
BBA-7th Semester
7/30/2019 W-4 the System Development Life Cycle (1) sameer
2/25
Abdus Salam 2
Week-4
System Development Life Cycle.
SDLC Stages or Phases
System Study
Feasibility studySystem Analysis
System Design & Coding
System Testing & Implementation
System Maintenance
7/30/2019 W-4 the System Development Life Cycle (1) sameer
3/25
Abdus Salam 3
At a Glance
System development revolves around a life cycle that beginswith the recognition of user needs, following a feasibility study.
The key stages of the cycle are evaluation of the present
system, information gathering, cost/benefits analysis, detailed
design, and implementation of the system.
The life cycle is not only a procedure that deals with hardware
and software.
It is computer based system to help the user operate a
business or make decisions effectively and manage an
enterprise successfully.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
4/25
Systems Life Cycle
Methodology
Recommended way of doing something
The systems approach or the basic methodology for solving problem
or
Systems approach to the task of developing and using a computer-based system
Often called waterfall approach
Consist a series of task that closely follow the steps of the system
approach and are performed in top down fashion.
7-4
7/30/2019 W-4 the System Development Life Cycle (1) sameer
5/25
Abdus Salam 5
System Life Cycle
Provides overall framework for managing systemsdevelopment process
System life cycle is an organizational process of developing
and maintaining systems.
It helps in establishing a system project plan, because it gives
overall list of processes and sub-processes required
developing a system.
To understand system development, we need to recognize that
the existing system has life cycle
7/30/2019 W-4 the System Development Life Cycle (1) sameer
6/25
Abdus Salam 6
System Life Cycle
Two main approaches to SLCPredictive approach:Assume project can be planned out in
advance
Adaptive approach: More flexible, assumes project cannot
be planned out in advance
Predictive or adaptive approach use SLC
All projects use some variation of SLC
7/30/2019 W-4 the System Development Life Cycle (1) sameer
7/25
Abdus Salam 7
SDLC Stages or Phases
There are six phases of SDLC System Study
Feasibility Study
Analysis of the Present System
Design & Coding of a Candidate System
Testing and Implementation of the System
Maintenance
Phases are not always sequential
Phases can overlap
Activities across phases can be done within an iteration
Phases are jointly called the System Development Life Cycle
7/30/2019 W-4 the System Development Life Cycle (1) sameer
8/25
Abdus Salam 8
SDLC Stages or Phases (Contd)
System Study It is the first stage of system development life cycle.
The key question is What is the problem?
Gives a clear picture of what actually the physical system is?
The system study is done in two phases.
In the first phase, the preliminary survey of the system is done which helps
in identifying the scope of the system.
The second phase of the system study is more detailed and in-depth study
in which the identification of users requirement and the limitations and
problems of the present system are studied.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
9/25
Abdus Salam 9
SDLC Stages or Phases (Contd)
System Study (Contd) After completing the system study, a system proposal is prepared by the
System Analyst (who studies the system).
The proposed system contains the findings of the present system and
recommendations to overcome the limitations and problems of the
present system in the light of the users requirements.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
10/25
Abdus Salam 10
SDLC Stages or Phases (Contd)
Feasibility Study On the basis of result of the initial study or initial investigation, feasibility
study takes place.
The feasibility study is basically the test of the proposed system in the
light of its workability, meeting users requirements, effective use ofresources and the cost effectiveness.
The main goal of feasibility study is not to solve the problem but to
achieve the scope.
In the process of feasibility study, the cost and benefits are estimated
with greater accuracy.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
11/25
Abdus Salam 11
SDLC Stages or Phases (Contd)
Feasibility Study (Contd) It focuses on three major questions
What are the user needs and how does a candidate system meetthem?
What resources are available for given candidate system?
What are the impacts of the candidate system on the organization?
Each of these questions must be answered carefully.
The objective of a feasibility study is not to solve the problem but to
acquire a sense of its scope.
The result of feasibility study is a formal proposal.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
12/25
Abdus Salam 12
SDLC Stages or Phases (Contd)
Feasibility Study (Contd) The proposal summarizes what is known and what is going to be done.
It consist of the following:
Statement of the problem
A carefully worded statement of the problem that led to analysis.
Summary of finding and recommendations A list of major findings and recommendations of the study.
Detail of finding
An outline of the methods and procedures undertaken by the existing
system, followed by coverage of the objectives and procedures of the
candidate system. Recommendation and conclusions
Specific recommendations regarding the candidate system, including
personnel assignments, costs, project schedules, and target dates.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
13/25
Abdus Salam 13
SDLC Stages or Phases (Contd)
System Analysis Assuming that a new system is to be developed, the next phase is
system analysis.
Analysis is a detailed study of various operations performed by a system
and their relationships within and outside the system.
During analysis, data are collected on the available files, decision pointsand transactions handled by the present system.
Interviews, on-site observation and questionnaire are the tools used for
system analysis.
All procedures, requirements must be analyzed and documented in the
form of detailed data flow diagrams (DFDs), data dictionary, logical datastructures and miniature specifications.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
14/25
Abdus Salam 14
SDLC Stages or Phases (Contd)
System Analysis (Contd) The main points to be discussed in system analysis are:
Specification of what the new system is to accomplish based on the user
requirements.
Functional hierarchy showing the functions to be performed by the newsystem and their relationship with each other.
List of attributes of the entities - these are the data items which need to be
held about each entity (record)
7/30/2019 W-4 the System Development Life Cycle (1) sameer
15/25
Abdus Salam 15
SDLC Stages or Phases (Contd)
System Design & Coding The term design describe a final system and the process by which it is
developed.
Based on the user requirements and the detailed analysis of a new
system, the new system must be designed.
This is the phase of system designing. It is a most crucial phase in thedevelopment of a system.
The key question is How should the problem be solved?
Normally, the design proceeds in two stages :
Preliminary or general design
Structure or detailed design
7/30/2019 W-4 the System Development Life Cycle (1) sameer
16/25
Abdus Salam 16
SDLC Stages or Phases (Contd)
System Design & Coding Preliminary or general design
In the preliminary or general design, the features of the new system are
specified.
The cost of implementing these features and the benefits to be derived are
estimated.
If the project is still considered to be feasible, we move to the detailed design
stage.
Structure or Detailed design
In the detailed design stage, computer oriented work begins
At this stage, the design of the system becomes more structured.
Input, output and processing specifications are drawn up in detail.
The programming language and the platform in which the new system will
run are also decided.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
17/25
Abdus Salam 17
SDLC Stages or Phases (Contd)
System Design& Coding Coding
After designing the new system, the whole system is required to be converted
into computer understanding language.
It is an important stage where the defined procedure are transformed into
control specifications by the help of a computer language. This is also called the programming phase in which the programmer converts
the program specifications into computer instructions, which we refer as
programs.
The programs coordinate the data movements and control the entire process
in a system.
This helps in fast development, maintenance and future change, if required.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
18/25
Abdus Salam 18
SDLC Stages or Phases (Contd)
Testing and Implementation of the System Before actually implementing the new system into operations, a test run
of the system is done removing all the bugs, if any.
It is an important phase of a successful system.
The output of the test run should match the expected results.
Using the test data following test run are carried out: Unit test
System test
Unit test: When the programs have been coded and compiled and
brought to working conditions, they must be individually tested with the
prepared test data. Any undesirable happening must be noted and debugged (error
corrections).
7/30/2019 W-4 the System Development Life Cycle (1) sameer
19/25
Abdus Salam 19
SDLC Stages or Phases (Contd)
Testing and Implementation of the System (Contd)
Unit Test
Systems test
Integration Test
Verifies all programs
in application work
together
Unit Test
Verifies each individual
program works by itself
Verifies each
individual
program works
by itself
7/30/2019 W-4 the System Development Life Cycle (1) sameer
20/25
Abdus Salam 20
SDLC Stages or Phases (Contd)
Testing and Implementation of the System (Contd) System Test:.
At this stage the test is done on actual data.
The complete system is executed on the actual data.
At each stage of the execution, the results or output of the system is
analyzed. During the result analysis, it may be found that the outputs are not
matching the expected out of the system.
In such case, the errors in the particular programs are identified and are
fixed and further tested for the expected output.
When it is ensured that the system is running error-free, the users arecalled with their own actual data so that the system could be shown
running as per their requirements.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
21/25
Abdus Salam 21
SDLC Stages or Phases (Contd)
Testing and Implementation of the System After having the user acceptance of the new system developed, the
implementation phase begins.
Implementation is the stage of a project during which theory is turned
into practice.
During this phase, all the programs of the system are loaded onto theuser's computer.
After loading the system, training of the users starts.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
22/25
Abdus Salam 22
SDLC Stages or Phases (Contd)
Testing and Implementation of the System Main topics of such type of training are:
How to execute the package
How to enter the data
How to process the data (processing details)
How to take out the reports
7/30/2019 W-4 the System Development Life Cycle (1) sameer
23/25
Abdus Salam 23
SDLC Stages or Phases (Contd)
Testing and Implementation of the System After the users are trained about the computerized system, manual
working has to shift from manual to computerized working.
The following two strategies are followed for running the system:
Parallel run: In such run for a certain defined period, both the systems
i.e. computerized and manual are executed in parallel. This strategy is helpful because of the following:
Manual results can be compared with the results of the
computerized system.
Failure of the computerized system at the early stage, does not
affect the working of the organization, because the manual systemcontinues to work, as it used to do.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
24/25
Abdus Salam 24
SDLC Stages or Phases (Contd)
Testing and Implementation of the System Pilot run: In this type of run, the new system is installed in parts.
Some part of the new system installed first and executed successfully
for considerable time period.
When the results are found satisfactory then other parts are
implemented. This strategy builds the confidence and the errors are traced easily.
7/30/2019 W-4 the System Development Life Cycle (1) sameer
25/25
Abdus Salam 25
SDLC Stages or Phases (Contd)
Maintenance Maintenance is necessary to eliminate errors in the system during its
working life and to adjust the system to any variations in its working
environment.
It has been seen that there are always some errors found in the system
that must be noted and corrected.
It also means the review of the system from time to time.
The review of the system is done for:
knowing the full capabilities of the system
knowing the required changes or the additional requirements
studying the performance If a major change to a system is needed, a new project may have to be
set up to carry out the change.
The new project will then proceed through all the above life cycle
phases.