Information Technology Reference
In-Depth Information
Concept
Feasibility
Specification,
Test, Plan
Requirements
Portioning &
Test Cases
Write, Debug
& Integrate
Validation
Design
Code
Test
Deployment
& Support
Maintenance
FIGURE 2.1
The steps in the Waterfall Model (2008).
a steep mountain. Once the water has flowed over the edge of the cliff and has begun
its journey down the side of the mountain, it cannot turn back. It is the same with
waterfall development. Once a phase of development is completed, the development
proceeds to the next phase and there is no turning back. This is a classic methodology
were the life cycle of a software project has been partitioned into several different
phases as specified below:
1. Concepts
2. Requirements
3. Design
4. Program, Code, and Unit testing
5. Subsystem testing and System testing
6. Maintenance
The term “waterfall” is used to describe the idealized notion that each stage or
phase in the life of a software product occurs in time sequence, with the boundaries
between phases clearly defined as shown in Figure 2.1.
This methodology works well when complete knowledge of the problem is avail-
able and do not experiences change during the development period. Unfortunately,
this is seldom the case. It is difficult and perhaps impossible to capture everything in
the initial requirements documents. In addition, often the situation demands work-
ing toward a moving target. What was required to build a year ago is not what is
needed now. Often, it is seen in projects that the requirements continually change.
The Waterfall Process is most suitable for small projects with static requirements.
Development moves from concept, through design, implementation, testing, in-
stallation, and troubleshooting, and ends up at operation and maintenance. Each phase
of development proceeds in strict order, without any overlapping or iterative steps. A
schedule can be set with deadlines for each stage of development, and a product can
proceed through the development process like a car in a carwash and, theoretically,
be delivered on time.
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