The Software Development Life Cycle - Software Testing: Testing Across the Entire Software Development Life Cycle - page 31

Planning stage

Analysis stage

Design stage

Implementation
stage

Cutover

Figure 2.1

The waterfall development life cycle

2.3.2 Prototyping

Although the sequence of the classical SDLC stages was intuitively logical,
there were two major weaknesses. First, it took from 3 to 5 years to go through
the stages in order. All too frequently, the business market targeted by the
new system had time to move out from under the new system. Second, there
was invariably a need to backtrack and repeat stages or portions of stages to
accommodate changes in business requirements or changes in the business
market.
Developers came to the conclusion that a better approach would be to ex-
pect that interim changes would be the rule rather than the exception. The
result was prototyping: the development of a system by means of a series of
iterations to incorporate midstream changes until the system meets all the busi-
ness requirements. Figure 2.2 shows how the prototyping stages are arranged
with any of the first four stages repeated until the user approves the prototype.
Stage names different from those in the classical SDLC are used in the figure,
but they continue the logical sequence that begins with planning and concludes
with implementation.
In some projects, the user is unable to specifi cally defi ne what the system will
accomplish and how it will accomplish it. In these cases, developers use prototyping
to defi ne the user's needs. This kind of prototype is called a requirements prototype .
The prototype is often just a nonoperational shell of the intended system. Once it
is approved, it serves as the blueprint for development of the system following an