Software Development Model

The V-Model is an SDLC model and also known as Verification and Validation Model. Here in this model process is executed in a sequential flow in a V-shape. The V-Model is an extension of the waterfall model and is based on the association of a testing phase for each corresponding development stage. Thus, for every single phase in the development cycle, there is a directly associated testing phase.

This is a highly-disciplined model and as its extension of Waterfall Model, the next phase can be executed only if the previous phase has completed its execution. The V-Model demonstrates the relationships between each phase of the development lifecycle and its associated phase of testing. Thus, one can say testing goes in parallel with a corresponding phase of development in V-model.

Water Fall Model Design:

The horizontal and vertical axes represent time or project completeness (left-to-right) and level of abstraction (coarsest-grain abstraction uppermost), respectively.

Sequential Phases:

1) Requirement analysis: In the first phase of the development cycle where the product requirements are understood from the customer’s perspective. The phase involves detailed communication with the customer to understand his expectations and exact requirement. This is a very necessary activity, as the needs of the customer should be known and understood properly. The acceptance test design planning is done at this stage as business requirements can be used as an input for acceptance testing.

2) System Design: Once the requirements are known, then the next stage is to develop a proper system design. The system design will have the understanding and detail of the complete hardware and communication setup for the product under development. The system test plan is developed based on the system design.

3) Architectural Design: Architectural specifications are understood and designed in this phase. Usually, more than one technical approach is proposed and based on the technical and financial availability the final design is made. The system design is divided further into modules having different functionality. This is also referred to as High-Level Design. The communication of the internal model and other systems is defined here.

4) Module Design: In this phase, the detailed internal design for all the system modules is specified referred to as Low-Level Design. It is necessary that the design is compatible with the internal model design and the other external systems. The unit tests help eliminate the maximum faults and errors at a very early stage. These unit tests are designed at this stage based on the internal module designs.

5) Coding Phase: The actual coding of the system modules from the design phase is taken up here in the Coding phase. The applicable programming language is decided based on the system and architectural requirements. The initial code is then reviewed and optimized before the final build.

6) Validation: Validation phase is further divided as follows:

• Unit Testing: Unit tests are designed in the module design phase is executed in the code during this validation phase. Unit testing helps eliminate and fix bugs at an early stage, though all defects cannot be uncovered by unit testing.

• Integration Testing: Integration testing is associated with the architectural design phase. Integration tests are performed to test the coexistence and communication of the internal modules within the system.

• System Testing: System testing is associated with the system design phase. System tests check the entire system functionality and the communication of the system under development with external systems. The software and hardware compatibility issues can be uncovered during this system test execution.

• Acceptance Testing: Acceptance testing is associated with the business requirement analysis phase tests the product in user environment. Acceptance tests uncover the compatibility issues with the other systems available in the user environment. It also identifies the non-functional issues such as load and performance defects in the actual user environment.

Applications:

Applications of V-model are much like Waterfall model, thus requirements need to be predefined.

One can apply this model in the following scenario:

• Requirements must be predefined and well documented.

• Stable product definition.

• Static technology.

• Small-Medium projects.

• Should be selected if ample technical resources are available.

Advantages:

• Complete one phase at a time.

• Simple and well-defined progress.

• Simple and easy to understand.

• Rigid model.

• Testing is done from the scratch.

• Ambiguities are known at every stage.

Disadvantages:

• Not suited for long, complex and altering project.

• Highly uncertain and risky.

• Once entered the testing stage, going back is very difficult.