The waterfall model is the testing model that follows a fixed approach for software development. It is an idealistic model which is useful when the projects are complex and have sufficient timelines. The Standish Group carried out a study and found that only 14% of Waterfall projects are delivered on or ahead of time as well as within budget, compared to Agile projects which recorded 42%. The waterfall is known for having a failure rate of around 29% due to its rigidity in being able to accommodate changes after the initial requirements phase. Rigid structure, lack of feedback, and late integration of testing are some reasons why Waterfall projects may experience cost overruns (up to 60%) and time overruns (50%). In this blog, we will be examining the waterfall model’s advantages and disadvantages.
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What is the Waterfall Model?
The waterfall model is the earliest Software Development Life Cycle (SDLC) method that was used for software development. It involves different phases, where each phase is executed linearly, meaning that the next phase can start only after the previous phase is completed. It is just like the flow of water, where the direction of flow cannot be reversed. The output of one phase serves as the input for the next.
Different Phases of the Waterfall Model
The waterfall model has six different phases, which are given below:
- Requirement gathering and analysis
- System design
- Implementation
- Integration and testing
- Deployment
- Maintenance
Waterfall Model Advantages and Disadvantages
The waterfall model presents both advantages and disadvantages that significantly influence project outcomes. Understanding these aspects is necessary for informed decision-making in project management and development. Let us see these in detail.
Advantages of the Waterfall Model
- Quality Assurance at Every Step: The waterfall model focuses on thorough quality assurance through verification and validation before moving on to the next stage. This helps identify and rectify errors early in the development process, reducing the chances of major issues later on.
- Thorough Documentation: In this model, well-structured documents like requirements specifications, design documents, technical specifications, and test plans are created. These documents are updated regularly to reflect any changes. It is beneficial for the developers, testers, and other stakeholders.
- Predictability in Project Management: This model makes it easier for project managers to plan resources, allocate budgets, and set realistic timelines.
- Easy to Understand: All phases involved are processed one at a time, making it easy to understand the entire development process. Tools such as Gantt charts or workflow diagrams are used to visualize the flow of tasks and dependencies. It makes the process more understandable to the people involved in product development.
Disadvantages of the Waterfall Model
- Rigidity and Lack of Flexibility: It is difficult to adjust the waterfall model to changing requirements because of its rigid nature. The sequential structure of this model makes it challenging to accommodate changes once a phase has been initiated. For example, if requirements change after the design phase has started, it may require major rework and can disrupt the entire development process.
- Testing at the Tail End: Testing is postponed in the development process, which may lead to a late identification of errors, which would make it more difficult to apply changes and increase the possibility of missing important problems.
- Not Suitable for All Projects: Making any changes or adjustments during the development process can be challenging, making it less desirable for complex projects.
- Documentation Overhead: The lengthy documentation process requires a significant time investment from developers and testers, which might slow the speed of development in general.
- Limited Client Feedback Incorporation: If clients are not involved in the development process, important client feedback might not be included until much later in the process. This limitation can result in a final product that may not entirely align with the client’s changing expectations.
Suitable Conditions to Use the Waterfall Model
It is best to use the waterfall model in the following cases:
- The system requirements are clear.
- The application is short and simple, i.e., not too complex.
- System requirements are fixed, meaning they are not going to change during the development process.
- The resources for development are available and trained.
- The tools and technology going to be used are stable and not dynamic.
Conclusion
In summary, the waterfall model has both advantages and disadvantages. It works well for projects with well-defined requirements, but because of its rigidity and late product visibility, it may not work well in more dynamic environments. As the software development field develops, teams must weigh the advantages and disadvantages of different software development approaches to figure out which best suits their needs and limitations.
FAQs
Why is it called the waterfall model?
The waterfall model is named so because the flow of development of the software is just like the flow of the waterfall, i.e., it cannot be reversed. It means that once we have moved on to the next phase, we cannot go back to the previous phase to make any changes.
Give an example of a waterfall model in real life.
Consider a construction project. We can build the roof of a house only after the walls have been built. Also, once we are building the roof, we cannot make changes to the walls of the house. This is a perfect example to demonstrate how the waterfall model works in real life.
What are the different phases of the Waterfall Model?
The typical phases include Requirements Analysis, Design, Implementation, Testing, Deployment, and Maintenance.
Is the Waterfall Model suitable for large-scale projects?
The Waterfall Model is often used for large-scale projects with well-defined requirements and where changes are expected to be minimal once the project begins.
What are the key differences between waterfall testing and Agile testing?
Waterfall is like building a whole car and then checking if it works, while Agile is like building and testing one part at a time, making improvements along the way.