Information Technology Reference
In-Depth Information
The Waterfall Model has some well-known limitations. The biggest drawback
with the Waterfall Model is that it assumes that requirements are stable and known
at the start of the project. Unchanging requirements, unfortunately, do not exist
in reality, and requirements do change and evolve. To accommodate requirement
changes while executing the project in the Waterfall Model, organizations typically
define a change management process, which handles the change requests. Another
key limitation is that it follows the “big bang” approach—the entire software is
delivered in one shot at the end. No working system is delivered until the end of the
process. This entails heavy risks, as the users do not know until the very end what
they are getting (Jalote et al., 2004).
To alleviate these two key limitations, an iterative development model can be
employed. In iterative development, software is built and delivered to the customer
in iterations. Each iteration delivers a working software system that is generally an
increment to the previous delivery. Iterative enhancement and spiral are two well-
known process models that support iterative development. More recently, agile and
XP methods also promote iterative development.
2.3.1.11.1
Advantages
With iterative development, the release cycle becomes shorter, which reduces
some of the risks associated with the “big bang” approach.
Requirements need not be completely understood and specified at the start of
the project; they can evolve over time and can be incorporated into the system
in any iteration.
Incorporating change requests also is easy as any new requirements or change
requests simply can be passed on to a future iteration.
2.3.1.11.2
Disadvantages
It is hard to preserve the simplicity and integrity of the architecture and the
design.
2.3.1.11.3
Suitability
Overall, iterative development can handle some of the key shortcomings of the
Waterfall Model, and it is well suited for the rapidly changing business world,
despite having some of its own drawbacks.
2.3.2
Agile Software Development
With the advent of the World Wide Web in the early 1990s, the agile software design
methodologies [also referred to as light weight , lean , Internet-speed, flexible, and
iterative (Kaner, 1996), (Juran & Gryna, 1988] were introduced in an attempt to
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