The waterfall software development model describes software engineering as a sequential process made up of distinct steps that proceed downwards, similar to a waterfall. Furthermore, once the process proceeds to the next phase, it cannot go back. The waterfall software development model has five phases – Requirements Analysis, Design, Implementation, Testing, and Maintenance.
Phase 1: Requirements Analysis
Requirements analysis is all about getting a clear picture of what the client wants. It is in this phase that the client should lay out the expectations of the program, including the problems that the program is supposed to address. All of this should be communicated in terms that are clear and simple enough for both parties to understand. Aside from merely defining the purpose of the program the, performance requirements should also be asked. Furthermore, the client’s business should be understood, as it helps to put the entire project in context and sets constraints for the programmers. This phase ends with a software requirements specification being drawn up. Being the first phase, requirements analysis is arguably the most important part of waterfall software development because it’s the first step in a process that, as mentioned earlier, only goes forward and doesn’t ever go back.
Phase 2: Design
Before any coding actually takes place, a design that satisfies the requirements specification should be created. Several aspects of software development should be formalized, including the hardware and software architecture, security and performance guidelines, data and database storage containers, choice of programming language and IDE. Other miscellaneous features of the final product are also drawn up such as accessibility and the user interface. The resulting design specification acts as a blueprint which shows both how the final product should look like, and what concrete steps the programmers should take to get there.
Phase 3: Implementation
It’s in the implementation phase that programmers actually start coding. This phase is completely based on the design specification created in the previous phase. The implementation phase usually involves a team of programmers working closely together with other specialists. Programmers use compilers, interpreters, debuggers and version control systems to facilitate their work. The specialist teams include user interface designers and media editors. The goals of the design specification are divided among these teams which initially come up with small parts of the final product called units. These individual units are created and tested according to the coding standards defined in the design specifications. The units are then integrated together to create the final product in line with the architectural design specifications.
Phase 4: Testing
In the testing phase, all individual units and the final product are tested methodically to verify that they are completely free from errors and meet all specifications laid out by the client from the first phase. A quality assurance team subjects the final product to test cases to verify that it passes all of the design and specifications defined earlier. There are three types of testing done. First is unit testing, which is done on individual core units. Second is the testing of the final product. The last one is called “acceptance testing”, in which the client, or a representative of the client, tests the product to see if it meets expectations. If errors are found, they are communicated to the implementation team for corrections. Aside from testing, the user manual and other documentation are created in this phase.
Phase 5: Maintenance
The maintenance phase starts from the time the product is delivered to the client and lasts until support for the product is dropped. In the maintenance phase, management is done on the product to make sure that it continually performs as desired. This is most significant right after the client starts to use the final product, since this is when problems that have not surfaced during testing are revealed.
Advantages of Waterfall Software Development
The waterfall software development model was developed during a time when all parts of software development were haphazard and cluttered. Being one of the first software development models, the waterfall method is one of the most well-known. Other advantages come predominantly from its rigid structure.
Every phase has to make sure that it has fulfilled all of its functions before passing the product over to the next phase. This minimizes, if not completely neutralizes, any problem while the development process is still in its early phases.
Another advantage is the fact that the waterfall software development model relies heavily on paperwork. This makes it easier to track the project’s progress and makes it easier for new teams to pick up where the previous team left off.
Disadvantages of Waterfall Software Development
The rigidity of the waterfall model is also the root of its disadvantages. It doesn’t allow for reviews and revisions, especially in the first two phases. Compounding this problem is the fact that most clients don’t really know what they want until they have tested a working prototype.
The waterfall software development model is one of the first ever software development methodologies, and it served its purpose well at the time of its invention. However, other software development methodologies have been created since that are more effective and efficient.