V Model of Software Development

This process model derives from the classic waterfall and was developed to regulate the software development process within German administration and military. It shares much in common with the waterfall model (including a propensity to attract criticism) but rather than model the processes as a cascade, it is visualized as a V .

On the left, we see the development phases leading up to software con­struction: the planning, design, and implementation work. The right-hand stream governs testing and approval.' Each level of test work is measured against the specification generated from the corresponding left-hand phase.

The V model's difference from the waterfall is more than the orientation of a diagram. The testing phases (in the right branch) can begin in parallel to the development work (the left branch), and are given an equal impor­tance. This is good because:

• Traditionally, testing is squeezed out during the dying stages of a slipping project. This is dangerous. Emphasizing testing as a keystone of the devel­opment process highlights this fact and helps to ensure product quality.
• We should always test more than the final software: reviewing and validat­ing at all stages of development work, from the requirements specification through to the completed software. The V model highlights this.
• In the Real World, testing and bug fixing often take up more than half of a project's total time. The waterfall model doesn't accurately reflect this.
• This model can save time from the entire development process, since the test plans can be drawn up as soon as each development phase is com­plete. This streamlined, parallelized work will bring forward the project's end date because we don't need to wait for the waterfall's implementa­tion phase to end before beginning test activity.

Questionnaire:

• What is V model?
• Explain more about the V model?