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.
Agile method and waterfall model both are distinct from one another. One of the initial decision every software developers have to face is that, which model to go for developing the software projects. Software development requires well planned guidance through the scratch till end of the process of the user acceptance and maintenance. When it comes to the software development, for selecting any kind of methodology the success of your project is decided before your work is commenced. Of course that is obvious it begins with planning and choosing the most effective framework for your project. For your guidance, we have put some points forth to help you decide, which methodology of software application development should be adopted.
The waterfall model is the old traditional development framework that was used in 1970’s. It is a linear sequential model where the output of each phase acts as an input of the following phase. Here the development flows from scratch to end like a waterfall as the name suggest. Waterfall was discovered by none, rather it was inherited from the enterprise resource software developers where once the production of first phase is completed it is impossible to go back to the previous phase. It is impractical and very much costly to manage. Here the coding is done after the requirements and designs are final out. In general terms, waterfall model deals with startup phase, planning phase, execution phase and closing phase. And as it is difficult to go back to the previous phase, requirements must be reviewed and approved by the customer. There is no room to update the error without scratching from the first, so a proper extensive planned should be made from beginning and executed carefully.
- As waterfall model is a sequential model, it is easy to understand and well manageable. Team doesn’t need any training or a knowledge for developing waterfall model.
- With this model, clients have much clear ideas of what to expect from this model i.e it’s cost, size, time frame.
- The process is properly documented since this method places high emphasis on requirements and design documentation.
- Its progress is more easily measured, as whole work is measured in advance.
- The main con for this development model is, once the first phase is completed, one can’t checkout the previous phase. Incase if any errors occur in testing, than it becomes dam expensive and difficult to modify the changes.
- In the first phase of the waterfall model, clients must identify their project requirements. However it is tough for them to identify what they want in the early stage of the project.
- If the customer is dissatisfied about its delivered software project, it is difficult to make changes, as all the deliverables are based on the documentation and customer will only be able to see their outcome at the end of the project.
Agile is the solution for the cons faced in waterfall model. In agile development model, incremental approach is followed instead of sequential one. In this approach design process is broken into individual model. Agile in terms of development is defined as a communication and flexibility of the project. Agile development tool uses variety of method in order to produce efficient result. This category is more adaptable than waterfall model as it has a good timeframe to work when requirement keeps on changing. Here you also get the flexibility to catch out the bugs found during the development as well as if you encounter any bug in testing, you can go back to the previous phase for its recovery. The sole aim for the each iteration is to produce the product which can to shown to the customer. And then feedbacks are given for the future iterations.
- In agile model, changes can be done at any time during the project development. And you can always, go back to the backlogs for any modifications.
- For the real time development, it gives the chance to improve at every phase.
- As the products are tested thoroughly at every sprints it is easy to deliver at the end of any cycle.
- As it allows you to add features as and when require, you can always add extra functionalities to keep your product to the industry standards.
- Generally Agile teams are very small, so team members of the agile must be highly skilled in the varieties of areas.
- Agile also depends on the capabilities of project manager. It can turn out into list of code sprint, if project manager is not careful about it. As a result your project may take more time and it can become expensive too.
- Here if the any team member leaves the project in between the development, it can be highly be a catastrophic which is unlikely in waterfall as it is document based.
Which is better? Waterfall or Agile?
Both Agile and Waterfall have their own approaches, advantages and disadvantages. On one hand, waterfall model is generally used for the static projects; it is not likely to make many changes throughout the project. In contrast agile is preferable for the smaller project where you can make infinite changes whenever you wish. As agile is more flexible than waterfall, you can meet the customer requirements more easily. If you think that, your requirements will be changing as per the industry standards than choose agile. If you know your requirements, exactly what you need than waterfall model is much better option. It’s obvious that when it comes for selecting the methodology between two, there is no correct or incorrect choice. You need to understand your requirements and choose it which is suitable for you.