System Development Life Cycle (SDLC)
A series of steps completed over a period of time by
analysts in the course of a system development or
maintenance project.
The main steps of the SDLC include
- Analyzing how the current system meets users’
information needs
- Providing a design for a new system or a modification
of an existing system to meet these needs
- Developing a system based on the design
- Implementing the system
- Maintenance
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System Development Life Cycle
Phase 1 :
Phase 2 :
Phase 3 :
Phase 4 :
Phase 5 :
Preliminary Investigation
System Analysis
System Design
System Development
System Implementation and evaluation
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Systems Request
Phase 1
Preliminary
Investigation
Preliminary
Investigation
Report
STOP
Replace IS
Phase 2
Systems
Analysis
System
Requirements
Document
Phase 3
Systems
Design
System
Design
Specification
STOP
STOP = Terminate Development
STOP
Phase 4
Systems
Development
Complete
Functioning IS
Waterfall model of SDLC
Phase 5
Systems
Implementation
and Evaluation
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Operational IS
• Phase 1 : Preliminary Investigation (Feasibility Study)
A written request from management or an end user
triggers the start of the systems development life cycle. This
written request is called a system request.
The purpose of the preliminary investigation phase is to
identify clearly the nature and scope of the problems mentioned
in the systems request. Because identifying the problem is the
focus of the preliminary investigation, this phase is sometimes
called the problem definition phase.
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• Phase 2 : System Analysis
The purpose of the systems analysis phase is to
learn exactly what takes place in the current system, to
determine and fully document in detail what should take
place, and to make recommendations to management on
the alternative solutions and their costs. Through the
process of fact-finding or requirements determination,
You first define all the functions performed by the
current information system. At the same time, you
determine what modifications are needed by the
organization in the improved version of the information
system.
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The end product you create for this life cycle phase
is the system requirements document, which documents
all end user and management requirements, all
alternative plans and their costs, and your
recommendations
to
management.
After
you
present
your
results from this phase to management, management
decides on the best alternative.
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• Phase 3 : System Design
The purpose of the systems design phase is to
determine
how
to
construct
the
information
system
to
best
satisfy the documented requirements. You must design all
required information system outputs, files, inputs,
application software programs, and manual procedures.
Also, you must design the internal and external controls,
which are computer-based and manual steps that
guarantee the information system will be reliable,
accurate, and secure.
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The design is documented in the system design
specification and is presented to the management and the
end users for their review and approval. Management
and end user involvement is critical so there is no
misunderstanding about what the IS is to do, how it will
do it, and what it will cost, After all systems design steps
have been completed and if the developments is not
terminated, you then enter the next phase, system
development.
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• Phase 4 : System development
System development is the phase during which
the information system is actually constructed:
application programs are written, tested, and
documented; operational documentation and
procedures are completed; and end user and
management review and approval is obtained. The end
product of this phase is a completely functioning and
documented information system. As is true with all
other phases, the system development phase ends after
management has reviewed and approved all results of
the phase.
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• Phase 5 : System implementation and
evaluation
After the system development phase is completed,
you then proceed to systems implementation. Activities
for this phase include conversion of data to the new
system’s files, final training of the end users, and the
transition from the old system to the new system. It is at
this point that the end users and management actually
begin to use the constructed IS.
As part of a complete systems development life
cycle, provision is made to allow for postimplementation systems evaluation at regular intervals.
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The purpose of these evaluations is to determine if the
information system operates as proposed, and if the costs
and benefits are as anticipated.
• After the SDLC: system operation
During the systems operation phase, changes will
need to be made to the information system. These
changes are classified as either maintenance or
enhancements. Maintenance changes are made to correct
errors or to conform with government requirements.
Enhancements are modifications that add or change
capability within the system. Adding new information to
an existing printed report and the addition of new report
are examples of enhancements.
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1 Identifying
problems,opportuni
ties, and objectives
2 Determining
information
requirements
3 Analyzing system
needs
7 Implementing
and evaluating
the system
6 Testing and
maintaining the
system
5 Developing
and documenting
software
4 Designing the
recommended
system
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Obsolete system
Systems
planning
New, related problem or requirement
Systems New implementation alternative or Systems
support
analysis
requirement
Implementation
error (bug)
Systems
Systems
implementation
design
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The PIECES Framework by James Wetherbe
P The need to improve performance.
I
The need to improve Information(or data).
E The need to improve economics or control costs.
C The need to improve control and security.
E The need to improve efficiency of people and machines.
S The need to improve service to customers, partners,
employees, and so on.
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