Fig1. Waterfall model
1.5.2 V-cycle
model
This model is an improved cascade model that limit return to
previous steps in case of anomalies. To enhance the software functionalities
the phases of the rising part, must submit information on the phases in other
side when errors are detected.
Further more, the V cycle highlights the need
to anticipate and prepare in stages down the "expected" of future steps rising:
as expected the validation tests are defined in the specifications, the
expected unit tests are defined in the design.
It helps us to manage and coordinate acceptance testing
activities, test defect management, test plan preparation and following
clients' project requirements.
The benefits of performing verification and validation
activities:
§ Improved software quality
§ Improved customer satisfaction
§ Reduced cost of development
§ Reduced cost of maintenance
Verification and validation activities are performed at every
stage of the software development lifecycle as depicted by the V-model
below;
![]()
Fig2. V-cycle model
1.5.3 Spiral model
This development describes the various stages of the V
cycle. By implementation of successive versions, the cycle starts by
proposing more full and hard product.
The spiral cycle emphasis risk management than V-cycle indeed,
the beginning of each interaction includes a risk analysis phase.
![]()
| 
