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What is the V model?

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The phases of the V model
Interaction between development and verification
Model V XT: further development of the Model V
Areas of application of the V model
Advantages and disadvantages of the V model
Alternatives to the V model
The advantages of the V model
The disadvantages of the V model


What is the V model?

The V model or four-level model is a model used in various development processes, for example, in software development . Its first version appeared in the 90s, but over time it has been refined and adapted to modern development methods. The basic idea, however, dates back to the 1970s and was conceived as a kind of further development of the waterfall model..

In addition to the development phases of a project, Model V also defines the quality management procedures that accompany it and describes how these individual phases can interact with each other. Its name is due to its structure, which resembles the letter V .

  1. The phases of the V model
  2. Interaction between development and verification
  3. Model V XT: further development of the Model V
  4. Areas of application of the V model
  5. Advantages and disadvantages of the V model
    1. The advantages of the V model
    2. The disadvantages of the V model
  6. Alternatives to the V model

The phases of the V model

First, the V model defines the course of a project in increasingly detailed individual phases:

  • At the beginning of the project, the model foresees an analysis of the specifications of the planned system (specifications phase).
  • The project is then completed with functional and non-functional requirements for the system architecture (functional phase).
  • This phase is followed by the design of the system, in which its components and interfaces are planned (design phase).
  • Once these phases are completed, the software architecture (coding) can be designed in detail.

It is now that, according to these plans, the actual development of the software begins. Next, the quality control phases will take place , also called verification or validation, which are always related to each of the development phases. Method V covers the following tasks:

  • Unit tests
  • Integration testing
  • System integration
  • Validation

Interaction between development and verification

The? V? of the model name refers to how the model compares the development phases with the corresponding QA phases . The left arm of the letter V contains the design and development tasks of the system, and the right the quality control measures of each phase. At the junction between the two arms, the implementation of the product is located. In software projects, this refers to the programming of the software..

The correct implementation of the planned software architecture is verified by unit testing . Here it is checked in detail whether the individual modules of the software exactly fulfill the required functions and actually deliver the expected results. To avoid errors, it is recommended to run these tests in parallel with development.

The integration tests examine the design of the system . Here it is verified if each of the components interacts with the rest as planned - for example, if all the processes provide the expected results. At this point, an incorrect result could indicate an interface problem..

The system test verifies whether the general system requirements defined when designing the system architecture have been met . These tests generally take place in a test environment that simulates actual customer conditions as accurately as possible.

At the end of the project, the analysis of the requirements is contrasted with the validation of the finished product . In it, the customer checks whether the specifications are met during operation. As a general rule, software performance is only superficially tested, that is, what the customer sees during daily use is checked. This is also known as a validation test.

Model V XT: further development of the Model V

In 2006, the V model was revised to reflect new principles such as agile development. The result was the V XT model. XT refers to Extreme Tailoring and describes the new possibility of adapting the model to the requirements of each project.

A fundamental idea behind this revision was to provide a model that could be versatilely adapted to projects of different sizes . On smaller projects in particular, the old method was often too expensive and therefore inefficient, but with the Model V XT it is possible to eliminate certain phases that would require extra effort.

In addition, the new model also includes explicitly customer-tuned task blocks. The old model only deals with the management of the project by the supplier before final acceptance. In the new model, the customer is more involved .

The model will continue to be periodically revised to reflect innovations in the software development process and improve its suitability for practical use. The latest version of the Model V XT is version 2.3.

Areas of application of the V model

The V XT model is a very entrenched model in the industry as it is publicly available. In most of the offers of new software projects by public authorities, the use of the V model is even mandatory and therefore is an essential pillar, especially in companies that develop software for public authorities and ministries. It can be implemented in software projects of any size, whether in companies, in the military sector or in the public sector. It is a tool that facilitates the organization and implementation of the development, maintenance and development of a wide variety of ICT systems.

Likewise, the V model can also be used in other areas of development, for example, for electronic or mechanical systems in research and science. In these fields of application, there are some adapted variants that reflect the typical process steps of the discipline.

Advantages and disadvantages of the V model

The main reason for the popularity of the V model is that it guarantees a high degree of transparency and offers clearly defined and understandable processes. Next, we give you a summary of the main advantages and points for improvement.

The advantages of the V model

  • Optimization of communication between the parties involved through clearly defined terms and responsibilities.
  • Risk minimization and better planning through fixed and predetermined roles, structures and results.
  • Improved product quality through tightly integrated quality control measures.
  • Cost savings thanks to transparent processing throughout the entire product life cycle.

In general, the model can help avoid misunderstandings and unnecessary work . It also ensures that all tasks are completed in the proper time and order and keeps downtime to a minimum.

The disadvantages of the V model

The four-tier model may be too simple to map the entire development process from the developers point of view. It is mostly focused on project management . In addition, its relatively rigid structure allows an inflexible response to changes during development, and therefore promotes a linear course of the project. However, if the model is understood and used correctly, it is possible to use the V model for agile development.

Alternatives to the V model

There are many models in software development that, depending on the project and the team, can be considered as software development methods. There is a relatively large variety of process models, such as the popular cascade and spiral models . The waterfall model is particularly suitable for small, linear projects, while the spiral model is recommended for projects with an iterative structure.