2.1 Waterfall Life Cycle
The Classic Life Cycle or Waterfall, also known as the “topdown”
approach, was proposed by Royce [9]. Up until the mid
80's it was the only model with a level of general acceptance. It
was derived from models used in traditional engineering activities
with the objective of establishing an order in the development of
large software products. Compared with other software
development models, it is more rigid and less manageable.
The Waterfall Model is one of the most important models ever
published. It is a reference to others, and serves as the basis for
many modern projects. Its original version was improved over
time and is still frequently used today [5].