What is the V-shaped model for system development? Explaining the process, benefits, and differences from the W-shaped model

“What is the V-shaped model of system development method?”
"What are the benefits of the V-shaped system development model? I want to know the basic concepts and processes!"

Some people in charge of system development may think like the above. First of all, the V-shaped model has the following advantages.

• Easy to clarify test content
• Easy to clarify who is responsible at each stage
• Easy to check project progress stage
• Relatively low risk of rework

The main advantage of this method is that it is easy to set the test content appropriately because the requirements are clearly defined at the beginning.Additionally, since the phases are raised one by one, it becomes easier to clarify the overall progress and the person responsible for each process. Management will be able to proceed smoothly.

In this article, we will explain in detail the basic information, processes, roles, and differences between the V-model and other methods of system development.

1.What is the V-shaped model for system development?

First, we will explain basic information such as the system development V-shaped model and process.

• What is the V-shaped model, a system development method?
• First of all, what is system development?
• What are upstream and downstream processes?

What is the V-shaped model, a system development method?

The V-shaped model is a method that categorizes each process of system development into requirements definition, design, implementation, and testing, and superimposes them on the appearance of the V-shaped model.This model particularly emphasizes the importance of the testing phase. The process is as follows

The left half of the V is where the requirements definition, basic design, and detailed design are placed, and the right half is where unit testing, integration testing, and system testing are placed. The tests are placed in response to the progression of development. The series of steps from 1 to 7 form a V, so it is called the V-model.

This geometry tightly links definition and design to each test. It is clear at a glance which test corresponds to which task. Therefore, it can be said to be an easy-to-use development model for those who want to thoroughly conduct and check each phase of testing.

One of the traditional and common development methods is the "Waterfall" method. However, the Waterfall method has the disadvantage that it is difficult to understand which task is being tested. Therefore, the V-model is often used because it is easy to understand and manage progress.

First of all, what is system development?

System development refers to the realization of tools and software that are useful for business. Although the word is similar to ``system construction,'' which involves combining existing systems and arranging an environment, system development is basically ``creating something new from scratch.'' Or you can think of it as ``the process you go through at that time.''

The basic process of developing such a system is as follows.

• design
• construction
• test
• introduction

Requirements definition is an important process for proceeding with development. If not done properly, problems may occur during the development and implementation stages. It is important to discuss and consider this carefully.

basic design

Next, move on to ``Basic Design.''Basic design is a process work that defines the overall structure and functions of the system in order to realize the contents summarized in the requirements definition.The main designs that can be considered are as follows:

While requirements definition determines the purpose of the system to be developed, basic design is the work of summarizing specific methods to achieve that purpose. Normally, specifications are determined based on a requirements definition document. This includes determining the screen design and infrastructure configuration. Therefore, be sure to make it easy for users to understand and share the image of the completed system as you proceed.

Detailed design

Next is "detailed design".Detailed design is the process of creating a blueprint of how to write a program to realize the contents determined in the basic design.The main designs that can be considered are as follows:

By adopting the V-shaped model, you can perform testing and verification according to each stage as shown in the table above. By making it clear what needs to be done, it will lead to fewer omissions and improved quality.

Easy to clarify who is responsible at each stage

Another feature of the V-shaped model is that it makes it easy to clarify who is in charge at each stage.This is because the people in charge of each process are clearly separated.

For example, if the current process is basic design, the person in charge will be the person in charge of operations. By introducing the V-shaped model, it becomes easier to understand each stage and the person currently in charge.

However, some projects may have tasks that span multiple stages. In this case, it can be difficult to know who is responsible for each stage, so be careful.

Easy to check progress stages

Adopting a V-shaped model makes it easier to check the progress stages of a project.This is because the process proceeds in stages in the V-shaped model.

In the V-shaped model, the start of each stage is conditional on the completion of the previous stage. For example, the detailed design can only proceed after the basic design is completed. Completion of each phase becomes a clear milestone.

In this way, the V-model has extremely simple progress processes and progress conditions, and basically no time is required to check them. As mentioned above, it is also easy to clarify who is responsible, making it easier to manage and track the status of the project.

Relatively low risk of rework

Another advantage of the V-shaped model is that the risk of rework is relatively low.This is because development begins only after requirements definition and design are completed.

In the V-shaped model, requirements are first defined strictly and then thoroughly documented and designed. The test level for each stage is clearly defined, and rigorous testing is performed at the end of each process. This makes it less likely that omissions will be discovered in the downstream process, compared to if you proceed with development without thinking. You can expect to prevent major rework.

However, this is just a ``relatively low'' rate, not an absolute one. For example, if a fatal flaw is discovered during the testing stage, there is a risk that the process may have to go back to requirements definition. please note.

Explaining the difference between V-shaped model, W-shaped model, and agile model

In system development, in addition to the V-shaped model, there are other methods such as the W-shaped model and the agile model. Here we will explain the differences from the V-shaped model.

• Difference between V-shaped model and W-shaped model
• Difference between V-shaped model and agile model
• Difference between V-shaped model and waterfall model
• Differences between the V-model and the prototype model

Difference between V-shaped model and W-shaped model

The "V-shaped model" progresses in stages from requirements analysis to development and implementation, whereas the "W-shaped model" progresses at the same time as the testing process as shown below.The process of the W-shaped model is as follows.

This allows immediate verification as requirements definition and design progress. Design errors can be found efficiently, making them easier to fix.

As mentioned above, the V-shaped model represents the development steps in a V-shaped model, and tests are performed in stages from requirements analysis to development and implementation. The testing period for the V-shaped model is different from that of the W-shaped model. The V-shaped model begins the testing process after development, but the W-shaped model involves testing and design in the first half.

The W-shaped model is a development method recommended for projects that want to identify design errors at an earlier stage.

Difference between V-shaped model and agile model

The ``V-shaped model'' progresses in stages, but the ``agile model'' is a method that allows for flexible and quick releases.The steps of the agile model are as follows.

*In the agile model, it is common to develop each function simultaneously.

First of all, the agile model is a development method that repeats a series of processes of requirements definition, design, implementation, and testing for each function in a short period of time. It's like repeating the PDCA cycle at high speed.

Since we repeatedly release each feature, we can respond flexibly to changes in demand. Not only that, it also makes it easier to factor in market changes that occur during the project.

In contrast, the V-shaped model is less resistant to changes in requirements that occur during the course of the project because development is carried out faithfully in accordance with the requirements specifications. Instead, we always test at each stage, so you can expect the quality of the final product to be high.

Therefore, if you want to respond flexibly to changes, an agile model is recommended.

Difference between V-shaped model and waterfall model

The ``Waterfall model'' is a model that progresses sequentially, and the V-shaped model is a model that incorporates a testing process at each stage.The steps of the waterfall model are as follows.

1. Requirement definition
2. design
3. programming
4. test
5. Operation/maintenance

The waterfall model divides the development of a system into stages and moves on to the next stage when one stage is completed. It is called a ``waterfall'' because the process descends from the top to the bottom like a waterfall, from requirements definition to system testing.

The waterfall model, like the V-shaped model, is characterized by clear objectives and deliverables for each stage. Easier project management and more control over the process.

On the other hand, the V-shaped model becomes V-shaped during the development stage of this waterfall model, and tests are incorporated into the process on the left. It has a feature that makes it easy to clarify the scope of the test.

The two models are very similar, and the V-model can be considered an advanced version of the waterfall model.

Differences between the V-model and the prototype model

A "prototype model" is a model in which a prototype is created and confirmed by the orderer.The basic process of the prototype model is as follows.

1. Requirement definition
2. design
3. Prototype production
4. Review and testing
5. Prototype modification
6. Main development
7. release

A prototype model is a method in which requirements are determined in detail based on user feedback, and once the prototype passes, the process proceeds to full product development. Because it actively incorporates user feedback at the upstream process stage, it has the advantage of being able to more accurately understand needs.

On the other hand, in the V-shaped model, there is a confirmation test for users in the downstream process. Therefore, compared to prototype models, it is difficult to change the requirements.

For these reasons, prototype models are recommended for projects that aim to flexibly respond to user requests for changes while ensuring that the final product better meets user expectations.

However, please note that the prototype model requires the creation and verification of a prototype, so it tends to require more man-hours and costs than the V-model.

summary

So far, we have explained the V-shaped model for system development. Using the V-shaped model for system development makes it easier to manage the entire project.Because each process is clearly defined, it will be easier to understand the test content and to clearly identify the person responsible.

The V-shaped model is not good at flexible specification changes, so it is best used for projects where the requirements can be clearly defined and there are few changes. If you're planning a project that isn't expected to change much, consider adopting the V-shaped model.

If you have any problems with system development, please feel free to contact us.