The Waterfall Model:
The Waterfall Model is a very popular
model to follow when undergoing systems analysis. It consists of 6 main steps
that allow for a well-structured, thorough analysis of current system, and
design of a newer model. The steps are as follows: definition, analysis,
design, implementation, testing and maintenance. The following is a short
description of each step.
1. Definition: This stage is where the
problem is fully outlined. A feasibility check will then be performed to see if
it is possible to improve the system firstly, then if it will be economically
and socially acceptable. As well as taking into account the costs of the
process itself, they must realise that the new system could potentially render
the jobs of some of their employees useless, warranting redundancy payments
which can also cost them a lot of money. A brief investigation also happens to
see roughly what needs to be done.
2. Analysis: This stage only proceeds if
the feasibility check from the previous step results in the recommendation of a
new system. More detailed research will then be carried out about the current
system; the analyst needs a full understanding of how exactly everything works
and what is done with all the data. This is not the end of the research as more
detail will be needed later on.
3. Design: To commence this step, a
system specification will be drawn out; this will detail all the features and
functions needed by the customer. The designers will then produce both a
logical and physical design, as well as a test plan.
4. Implementation: This is when the new
system is put into place. It is usually done one of three ways: direct, phased
or parallel. Direct implementation is when the new system is immediately
implemented – there is no changeover period. Phased implementation is when the
new system is implemented in small parts over time; and parallel implementation
is when the new system is run alongside the current, while continuing to test
5. Testing: The test plan will then be
run to ensure the system is functioning properly; If any errors are found, they
will be corrected. When the testing stage is completed, the system can then be
passed onto the users.
6. Maintenance: The final stage of the
Waterfall Model is the maintenance stage. This stage will continue throughout
the life of the new system. It involves regular maintenance where any newly
discovered problems are fixed and any new features can be added.
Advantages of the Waterfall Model:
is easy to use as each step is fairly self-explanatory;
phases are all separate- there is no overlap. This means each stage can have
the full attention of the team, reducing the likelihood of errors;
stage can have clear goals/deadlines set, helping the team to be more
time-efficient and meet deadlines easier; and
to the separate stages, the development process can be very structured,
allowing each step to be a task on its own.
Disadvantages of the Waterfall Model:
the initial requirements are wrong in any way, the final system will have those
flaws present, and this will be very difficult to change;
users are not very involved outside of the definition phase, so they can’t
point out any flaws in the systems as it is developed;
is very easy for the systems to overrun in terms of time and budget; and
product won’t be tested until the end of development, so any mistakes will be
very hard to detect until the end, making the initial maintenance longer.
Appropriate Uses of the Waterfall Model:
to the disadvantages listed previously, it is best to use this model when
working on smaller projects that can be completed in a shorter amount of time.
is also wise to only use this if the user is certain they have all of the
requirements/specifications ready at the definition phase, due to the
difficulty in changing these later on.