The waterfall model is one the most popular methodology of software development life cycle (SDLC) in software engineering. It is the traditional approach followed in SDLC which is also described as a linear and sequential flow. It is the first model to be introduced, being highly simple and quite easy to understand. It has some different goals for each phase of development.
In the waterfall model, each phase must be completed before the next phase can begin without overlapping in the phases. For instance, imagine the water falling from the mountain cliff. Once the water starts flowing from the cliff, it cannot move in the upwards direction. Likely, waterfall model follows the same strategy. Once the development phase is completed, there is no U-turn and it needs to move further towards the next phase.
At the end of each phase, reviews take place to keep checks whether the project is flowing on the right path and whether to continue or discard the project. The concept of Waterfall model was introduced in 1970 by Winston M. Royce.
Waterfall model is the highly approached model, ensuring the success of the project. This waterfall model has typically divided into distinct phases and the outcome of one phase acts as an input for the next phase.
- Requirements: This is the first phase of development in the waterfall model where all the necessary requirements are gathered and captured in this phase and properly documented in the requirement specification documentation.
- Analysis: In the analysis phase, requirements are studied and verified. The analysis is done to check, whether the requirements specified are valid or not.
- System Design: The design of the system is prepared by studying the requirements specification documentation. This guides you in developing the architecture of the system and also helps in defining the hardware and system configurations.
- Implementations: After the developing the architecture of the system, project move towards the implementations. Here, from the inputs of the system design, the system is implemented into small programs which are tested after getting completed and moved towards the next phase. This testing is called unit testing. These small programs are, especially for its functionality and performance.
- Testing: After the implementation of the project is completed, testing phase initiates to test the each component to verify whether it is working in a specified way or not. Post integration of every unit testing is done to find faults and failures.
- Deployment: Once the final testing is done and made sure of having no bugs in the project, a project is ready for its final release. It is deployed in the customer environment at the end for the user to use the system.
- Maintenance: In this last phase of software development, projects are maintained and always checked whether users are using error free or not. If any issues arise from the client environment, patches are released, and even better versions are upgraded for the better user experience and updates are delivered.
Advantages of waterfall model
- Very easy to understand and implement as well as fewer resources are required to develop a project
- Higher chances of project visibility as every check are done at all sprints. By this client can make out the progress of the project
- It becomes very easy in deciding the milestones of the projects as timeframes and deadlines can be set from time to time completion
- Highly systematic and well-organized structure followed in developing the project.
- Process and results are well documented
Disadvantages of waterfall model
- Once the first iteration of the application is completed, you need to proceed further. You can’t do any modification in the previous stage.
- You can’t get all requirement at one go. Hence your requirement can’t get a freeze. In this case, an output of one phase is carried forward to the next phase.
- The high amount of risk and uncertainty.
- Too many changes disturb the rhythm of development.
Projects where Waterfall model is suitable
- Database related software
- E-commerce website
- Network Protocol software
There are multiple software development methodologies. Every such methodologies has its pros and cons. The decision of which process to use depends on multiple criteria and on case-to-case basis. One should always prefer to consult with a professional software development company or consultants to get the desired results.