What is V-model and advantages and disadvantages of this model

What is V-model ?

– V- model means Verification and Validation model.
– Each phase must be completed before the next phase begins.
– Testing of the product is planned in parallel with a corresponding phase of development.

V- Model Design and Flow-

V model has the different phases as shown in the above diagram.

Advantages of V-model:

  • Simple and easy to use.
  • Testing activities like planning test designing happens well before coding. This saves a lot of time. Hence higher chance of success over the waterfall model.
  • Proactive defect tracking – that is defects are found at early stage.
  • Avoids the downward flow of the defects.
  • Works well for small projects where requirements are easily understood.

Disadvantages of V-model:

  • Very rigid and least flexible.
  • Software is developed during the implementation phase, so no early prototypes of the software are produced.
  • If any changes happen in midway, then the test documents along with requirement documents has to be updated.


What is Spiral model and what is advantage and disadvantage of this model?

What is Spiral model?

  • Spiral model is a combination of sequential and prototype model.
  • This model is best used for large projects which involves continuous enhancements.
Spiral Model design and flow-

The spiral model has four phases.

  1. Planning phase
  2. Risk analysis phase
  3. Engineering phase
  4. Evaluation phase.

1. Planning Phase:

  • Requirements are gathered and analysis.
  • Doing feasibility study
  • Developed the Requirements like ‘BRS’ that is ‘Business Requirement Specifications’ and ‘SRS’ that is ‘System Requirement specifications’.

2. Risk Analysis:

  • To identify risk and alternate solutions.
  • If any risk is found during the risk analysis then alternate solutions are suggested and implemented.

3. Engineering Phase:

  • Development and testing of the software takes place in this phase.

4. Evaluation phase:

  • Customers evaluate the software and provide their feedback and approval


Advantages of Spiral model:

  • High amount of risk analysis hence, avoidance of Risk is enhanced.
  • Good for large and mission-critical projects.
  • Strong approval and documentation control.
  • Additional Functionality can be added at a later date.
  • Software is produced early in the software life cycle.

Disadvantages of Spiral model:

  • Can be a costly model to use.
  • Risk analysis requires highly specific expertise.
  • Project’s success is highly dependent on the risk analysis phase.
  • Doesn’t work well for smaller projects.