V model: Software Engineering

V model: Software Engineering

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Updated on Nov 11, 2022 16:18 IST

V model is a software development lifecycle model (SDLC), in which each step executes in a sequential manner with parallel testing for each development stage. This article includes V model phases like verification and validation.As well as it includes advantages and disadvantages of v model.


V model is a model in software engineering which describes how software should be developed. It originates in the military, aerospace, and information technology sectors, where safety and quality are of utmost importance. V model testing starts in parallel so that bugs can be caught early. Thus, his V-shaped model of the software industry is used for software development.

Table of contents

What is V Model?

The V model is an SDLC model in which process execution occurs sequentially in a V shape. This is also called the validation and validation model.

The V model is an extension of the waterfall model and is based on assigning test phases to corresponding development stages. This means that every development cycle has a directly linked testing phase. This is a highly disciplined model; the next phase will only start after the previous one is completed.

V model – design is a method for structuring and planning computer software development. The first step in implementing an idea in software engineering is to model the system conceptually. Conceptual modeling involves creating models using diagrams, tables, flowcharts, or other means to accurately and thoroughly depict a system. Before starting development, the model should be clear, concise, and easy to understand. After conceptually modeling the system, developers start developing the source code for the application. During this phase, developers must test the source code thoroughly to avoid making any mistakes that would negatively affect the end product.

Let us use the diagram above to understand this model. Here you can see that each development phase is connected to a test phase. The development and testing happen in parallel, as shown in the diagram. The left half of the V represents validation, the right half represents validation, and both halves are connected by a coding phase that gives the V. During the validation phase, static analysis is performed. Check if the current phase meets the desired requirements without executing the code. During the validation phase, dynamic analysis is performed. Verify whether the current phase meets the desired requirements the customer makes for the software by running the code.

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When to use the V model?

  • Small to medium projects with well-defined and fixed requirements.
  • Sample technical resources are available with the required technical expertise.
  • Customers’ requirements cleared.

V-model phases

Verification phase

The primary purpose of the verification process is to ensure the quality of software applications, designs, architectures, etc. Validation processes include activities such as reviews, walkthroughs, and inspections. Are you building the right product? This line is used for Verification. After reading it, you can understand that this line is asked during the project development. So basically, Verification is done when the process is in the development phase and is not complete. So Verification is done after every phase of project development.

1. Business Requirements Analysis

In this phase, customer requirements and needs are understood. What the customer expects from the final software and what features the customer wants are all discussed during this phase. This is a very important stage as there often needs to be more clarity between both customers and developers regarding the end result of the software. In this phase, acceptance tests are performed. 

2. System Design

This phase determines the actual design of the system. After the requirements analysis phase, the full design of the system is considered based on the final requirements. This includes hardware and communication setup requirements.

3. Architectural Design

This phase is also called High-Level Design (HLD). After the system design is analyzed, the architecture of the system is determined. It consists of various modules, database tables, UML diagrams, etc. All communication between the system’s internal modules and external systems is understood during this phase.

4. Modular Design

This phase is also called Low-Level Design (LLD). After analyzing the high-level design, each component of the high-level design is discussed in detail. The system is broken down into small modules in the module design phase. The compatibility of individual internal modules and their feasibility is checked. During this phase, unit tests are executed.

5. Implementation and testing

After the implementation phase is complete, the team tests their software. If testing reveals errors in the software, developers must be able to identify and resolve these issues quickly so that users can safely interact with their software. Once bugs are fixed, Verification begins- a process in which independent parties test the software to ensure it functions as advertised.

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Validation phase

Validation in software engineering is a dynamic mechanism for verifying that a software product meets the customer’s requirements accurately. This process helps ensure that the software provides the desired benefits in the right environment. The validation process includes integration testing, unit testing, system testing, and user acceptance testing. Have you built the right thing? This line is used for validation. After reading it, you can understand that this line is asked after a product/project is completed.

  1. Unit Testing: In unit testing unit Test Plans (UTPs) are created during the module design stage in the V model. 
  2. Integration Testing: In integration testing an integration test plan is created during the architecture design stage. 
  3. System Test: In system testing, system test plan is created during the design stage. 
  4. Acceptance Testing: In acceptance testing refers to the business requirements analysis part.

Advantages of V model

  • This is a very professional model for developing software.
  • Covers all functional areas. 
  • It contains instructions and recommendations that provide a detailed description of the issue encountered. 
  • Emphasize the importance of testing and ensure testing is planned. There are significant changes to catching bugs in the early stages. 
  • Test planning and design are performed during this phase as pre-coding testing activities.

Disadvantages of V model

  • V-model as being too rigid or prescriptive when applied to real-world situations.- For example, some critics point out that no project is ever completed according to an exact timeline when actual software development occurs
  • The risks are high and unpredictable.
  • This model is not suitable for complex projects.
  • After completing the testing phase, it isn’t easy to go back to the previous phase.
  • This is a poor model for long-running, ongoing projects.


The SDLC model is commonly used to understand the project workflow when starting a project. Based on the scenario, many models are available and followed by technicians. The V models below this are for budgets and other small projects.

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