The systems development life
cycle (SDLC) is a conceptual model used in project management that
describes the stages involved in an information system development project,
from an initial feasibility study through maintenance of the completed
Various SDLC methodologies have
been developed to guide the processes involved, including the waterfall model (which
was the original SDLC method); rapid application development (RAD); joint
application development ;
the fountain model; the spiral model;
build and fix; and synchronize-and-stabilize. Frequently, several models are
combined into some sort of hybrid methodology. Documentation is crucial
regardless of the type of model chosen or devised for any application, and is
usually done in parallel with the development process. Some methods work better
for specific types of projects, but in the final analysis, the most important
factor for the success of a project may be how closely the particular plan was
In general, an SDLC methodology
follows the following steps:
1. The existing system is evaluated.
Deficiencies are identified. This can be done by interviewing users of the
system and consulting with support personnel.
2. The new system requirements are
defined. In particular, the deficiencies in the existing system must be addressed
with specific proposals for improvement.
3. The proposed system is designed.
Plans are laid out concerning the physical construction, hardware, operating
systems, programming, communications, and security issues.
4. The new system is developed. The
new components and programs must be obtained and installed. Users of the system
must be trained in its use, and all aspects of performance must be tested. If
necessary, adjustments must be made at this stage.
5. The system is put into use. This
can be done in various ways. The new system can phased in, according to
application or location, and the old system gradually replaced. In some cases,
it may be more cost-effective to shut down the old system and implement the new
system all at once.
6. Once the new system is up and
running for a while, it should be exhaustively evaluated. Maintenance must be
kept up rigorously at all times. Users of the system should be kept up-to-date
concerning the latest modifications and procedures.