V-Shaped Model.... Extension of Waterfall Model...

In continuation of our previous discussion we can now give a glance to another model called V-shaped model, which can play a vital role in Software Development. The V-Shaped model is the same as the Waterfall model except that testing is a consideration throughout the development. Each stage of development is matched with its equivalent stage in testing.

Just like the waterfall model, the V-Shaped life cycle is a sequential path of execution of processes.  Each phase must be completed before the next phase begins.  Testing is emphasized in this model more so than the waterfall model though.  The testing procedures are developed early in the life cycle before any coding is done, during each of the phases preceding implementation.

Instead of moving down in a linear way, the process steps are bent upwards after the coding phase, to form the typical V shape. The V-Model demonstrates the relationships between each phase of the development life cycle and its associated phase of testing.

The V-Model demonstrates the relationships between each phase of the development life cycle and its associated phase of testing. The horizontal and vertical axes represents time or project completeness (left-to-right) and level of abstraction (coarsest-grain abstraction uppermost), respectively.

Pros: 

• Not quite as straight forward as the waterfall method, but quite straight forward none the less.
• Allows for more extensive testing, as the testing is built into each phase of development, rather than as an afterthought (allows for more than black box testing).
• More bugs are caught during development than are caught using the waterfall method.
• Project can move fairly quickly to implementation stage.

Cons:  

• Requires a very specific description of requirements and very little volatility in requirements.
• Bugs are expensive to fix in the final product, although more bugs are caught during development than are caught using the waterfall method.
• Total development time is longer than the waterfall method.