What Is the V Model and How Can It Improve Your Development?

Updated January 26, 2023

The V model is a project management system that’s popular in software and web development. This model uses sequential phases paired with validation tests that allow the development team to set clear expectations and identify potential flaws throughout the process without needing a final build first. Learning about the V model process may help you determine if it could be beneficial for your projects.

In this article, we discuss what the V model in software development is and how it works, list its different stages, share the benefits and challenges it presents and provide tips for implementing it.

What is the V model?

The V model is a development protocol that places an emphasis on developing and implementing testing procedures throughout the developmental process. The model relies on a sequential approach beginning with larger goals, then progressing on to the systems and ultimately individual components which comprise the project. Each phase pairs with a corresponding test that allows developers to perform mid-development assessments of the functionality of a project, allowing for earlier challenge identification to save time and resources.

How the V model works

When creating a V model, the project manager includes the main tasks and features their team needs to work on throughout the project life cycle to meet all the customer's requirements. The V model is similar to the waterfall model, which organizes these steps in a sequential life cycle. While the waterfall method uses a linear fashion to list each task, the V model uses a V-shaped graph.

On the left side of the V-shaped graph, the project manager includes details for each of the verification phases. These phases illustrate what the customer's requirements are and how the team plans to achieve them. The right side of the V represents the validation phases. This includes the specific tests the team must perform to validate whether the software meets all the customer's requirements.

Verification stages of the V model

In the verification stages, teams evaluate and review the product development without executing the code. This helps them determine whether the product meets all the customer's requirements. Here are the verification stages of the V model:

Business requirement analysis

Business requirement analysis is the first phase in the development cycle. During this phase, the project manager communicates with the customer to understand their needs and expectations. This allows the project manager to determine the exact requirements of a project. The project manager uses this information to create an acceptance test design plan, which lists all the customer's requirements for the project so their team has a clear set of guidelines to follow. They also create user acceptance tests (UATs) so they can test the user experience later during the user acceptance testing validation stage.

System design

During the system design phase, the team identifies the practical application for the project they’ve developed. This comprises identifying the different functions the project should accomplish after completion and how those functions interact with each other or with outside elements. During this phase, the company also develops the system tests that ensure the entire system functions properly and that the team can apply during testing in the later stages of development.

Architectural design

In the architectural design phase, the team plans out the infrastructure of the developmental projects. During this phase, developers define the components of the project and how they relate to and interact with each other. This provides the framework for understanding how the project functions when completed. Developers also create the integration tests in this phase, creating tests that allow the team to ensure the individual systems within the project can communicate and interact with each other correctly.

Module design

During the module design phase, the team creates a detailed internal design for each system module. Often referred to as low-level design, the module design phase involves breaking the system down into smaller units that are easier to build. The module design document outlines all database tables, interface details, dependency issues, error message listings, inputs and outputs so that programmers can begin coding each module.

Teams also create unit test plans (UTPs) during the module design phase so they can assess the performance of each module later in the unit testing validation phase.

Implementation

During implementation, programmers select which programming language to use based on the system and architectural design requirements. Then, they begin coding each module. They also test the code and optimize it as needed to improve performance. When they complete a module, they can add it to the repository, which is a central file storage location that houses all the source code files for a specific program.

Validation stages of the V model

In the validation stages, the team executes the code to perform functional and nonfunctional tests. This helps them evaluate the software after development to ensure the final product meets the customer's requirements. Here are the validation phases included in the V model:

Unit testing

During the unit testing stage, the team uses the UTPs developed in the module design phase to test the code, identify potential issues and develop solutions. Since modules are the smallest element in a program, executing UTPs can help teams verify that every part of the program is functioning correctly. It can also help them find the root cause of potential issues so they can resolve them quickly.

Integration testing

As the team clears components for implementation, they can enter the integration testing protocols. In the integration testing stage, the team revisits the integration test plans they created during the architectural design phase. They use these tests to assess whether individual units within the program can coexist and communicate with each other as needed. Once the team executes the integration test plans, the project manager develops a report to share the test results with the customer and other key stakeholders.

System testing

During the system testing stage, the team reviews the system tests they developed during the system design phase. These tests focus on making sure the completed project meets all the client's requirements. Instead of testing individual units and components, the team tests the entire system during this stage. This provides them with a holistic understanding of the overall functionality, interdependency and communication performance of the program. Some types of system tests you may perform during this stage include stress testing, load testing and regression testing.

Acceptance testing

In the acceptance testing stage, the team uses the user acceptance tests (UATs) created during the business requirements analysis phase to determine whether the program meets the user's requirements. Teams typically perform UATs in a real user environment to collect accurate data. This helps them identify areas for improvement before they complete the project. If the program passes all the UATs, it’s ready for people to use in real time.

When to use the V model

Project managers typically use the V model for small- to medium-sized projects that have clear requirements. Since the V model focuses on planning and testing features instead of creating prototypes, it’s important to make sure you fully understand the customer's requirements if you choose to use this model. Consider using the V model for a project if you're confident that you’ve established fixed and well-defined requirements. Ensure you have the technical resources and expertise available to complete each of the verification and validation stages.

Benefits of the V model

Many project managers use the V model to provide their teams with structure when working on a new project. Here are some of the benefits of using the V model in software development:

Provides clear guidelines by focusing on one phase at a time
Uses a simple and easy-to-understand framework
Establishes specific deliverables to make delegating tasks and tracking progress easy
Includes a review process for each phase to ensure accuracy
Promotes high-quality design and development
Includes thorough documentation of each phase

Challenges of the V model

While there are many benefits of using the V model, there are also some challenges you may experience. Here are a few challenges of using the V model:

The structured approach can be time-consuming for large projects.
It’s a rigid structure, which can make alterations challenging.
Delayed implementation can reduce early prototype opportunities.
Changes during the execution of a project may require updated work across all phases.

Tips for using the V model

If you believe that using the V model may be beneficial for your next development project, these tips may help you implement it successfully:

Gather comprehensive information. When creating a developmental project, it's beneficial to have as much information as possible. Hold discussions with any clients or stakeholders on the project to ensure you have a thorough understanding of their requirements and expectations prior to development so you can create a project that meets their needs.
Create meaningful tests. The strong reliance on phase-based testing is the key differentiator between the V model and waterfall model, and it requires diligence for effective implementation. Consider all the important responsibilities or expectations for each phase and ensure that your test accounts for each of them.
Encourage questions. When managing a team with the V model, it's important for all members to understand the expectations and goals of the project. By encouraging questions, you provide the opportunity for staff to clarify any areas of uncertainty to increase their potential to deliver effective code.
Set clear targets. Provide clear expectations for the project on the macro level and during each phase. Having a defined target to aspire to can provide a focus for developers working on a project.