What is The Waterfall Model?
The waterfall model is a popular software development process used to define the technical approach and implementation method for developing and maintaining complex software systems.
The model, which consists of sequential phases (or stages), has been criticized as being too rigid due to its linear structure, inflexible documentation requirements, lack of mechanisms supporting change management, and in general as it does not take into account the inevitable changes that occur during software development due to a variety of factors.
The Waterfall Model is not really a model but rather what we call a “methodology”. While the methodologies for software development are well documented, they do differ depending on their target audience and the business domain being addressed.
Definition of ‘Waterfall Model’
A waterfall model is a traditional approach to system development that starts with collecting requirements and then moves sequentially through the development process. Each phase requires the previous phase to be complete for it to proceed, as there should be no overlap of phases.
Every stage has input from its predecessor, so each stage relies on the accuracy of its preceding one. It is a “closed-loop” system and once it starts, little can be changed.
Waterfall Model In Software Engineering
At its core, the model does discuss some very important points that should be addressed when developing a complex software system:
- The Waterfall Model clearly defines all aspects of the development process and documents each stage to ensure there are no inconsistencies between phases.
- Defines a specific software development life cycle in which there are clearly defined phases.
- The Waterfall Model is well suited for very stable environments where requirements and scope are agreed upon before any coding begins.
- There is a need to manage the business expectations, as they directly relate to the risk and uncertainty associated with the project. The delivery of the software product is also directly affected by business expectations. The Waterfall Model provides a clear path and delivery mechanism to its stakeholders.
- The Waterfall Model clearly states that once in a phase, you cannot go back to a previous phase (cannot be redone). This can cause problems when many defects are found late in the testing phase and time to fix them may not be available.
- Provides a clear deliverable at the end of each phase.
Waterfall Model SDLC
The waterfall model is often misunderstood as a sequential development process, based on strict adherence to a fixed set of steps. In reality, it is much more fluid than that and provides many options for asynchronous processes, parallel development, and deferred steps. It is very much a process for managing project risk, which means it needs to allow flexibility to respond to changes.
Waterfall Model For Software Development
The waterfall model was originally developed by Winston W. Royce in 1970 for use in developing computer hardware systems although it wasn’t called a ‘waterfall model’ until 1975 by Barry Boehm.
The waterfall model is actually more of a method than a model in that it doesn’t specify any precise steps for software development. Instead, each step within the overall process must be defined in detail.
For this reason, the Waterfall Model can vary dramatically depending on the type of software to be developed, the size of the team, and what’s specified in the project’s documentation.
It does however follow an overall pattern that can be modified but not deviated from too much as it is still a sequential process. For this reason, it is sometimes referred to as a step-wise model since all processes are followed step-by-step, but it’s not a well-defined process.
One of the reasons why the Waterfall Model has become so popular is that software development projects can be broken down into manageable chunks of work called processes.
And each process can be assigned to a team or group of people with a specific set of skills and knowledge to undertake the task. This ensures that the different elements of a software development project are developed in a logical order, so nothing is missed out and the result is successful.
The Waterfall model consists of numerous phases or stages, each one dependent on the previous phase being completed successfully before moving onto the next stage.
If any obstacles arise during development that causes major delays it can be difficult to catch up. In addition, if any major changes are required, the model would have to be updated and all subsequent phases re-worked. This is why the Waterfall Model has been criticized as being inflexible in its approach and potentially leading to a lot of wasted time and money.
Waterfall Model Phases
Throughout the phases in the Waterfall Model are a series of processes that need to be followed for everyone to work together effectively and efficiently. There is an overlap between some of these processes which are necessary for team members to be able to communicate effectively so they are not isolated from one another.
Waterfall Model Processes:
- Feasibility study
- Requirement analysis
- Coding and unit testing
- Integration and system testing
An extensive amount of planning must be carried out before work can begin on each stage and this may take some time, probably the most important phase in the whole model to get right as any problems encountered during this process could trigger a lot of time, effort and money to be wasted if not taken into account.
The requirements for each stage must be specified in depth so that everyone knows what they are expected to achieve and how the final product should work when it’s completed. In addition, any changes or improvements will need to go through this phase again which may cause delays throughout the overall development process.
Significant time is spent on communicating and coordinating work between team members as many processes need to be undertaken simultaneously.
Let’s Discuss each of the SDLC Waterfall models phases in detail:
A feasibility study is an investigation that assesses the issues, risks, and costs of a project. It’s usually undertaken before any implementation takes place to determine whether it would be possible to continue with the given project or not.
The main purpose of a feasibility study is to discover why a project needs to take place and what the potential outcome will be. The feasibility study, therefore, aims to determine whether the project is technically and financially viable so that if it is, then it can go ahead.
This stage of the Waterfall Model involves different activities such as:
- Gathering information about the requirements for a specific project or product; – Establishing and understanding what will be required to carry out the project and whether any potential problems or issues may arise along the way;
- Determining how much time, money, and other resources will be needed to successfully implement a given project if it were to go ahead;
- Establishing what is required of different members of the team throughout a development process.
The requirements should be gathered and documented before any development in the next phase of the Waterfall Model takes place. The goal is to understand what will be required to implement a project – including who needs it, what features it must have, and how the end product will work.
During this stage of the Waterfall model, the team will also determine which requirements are feasible and which will be discarded.
Once all of this has been done, the next step is to document the information that has been gathered in a requirement document that everyone can refer to when carrying out work for each stage.
Determining how a product or service should run is crucial so that when requirements have been gathered, the team will need to go through them and determine whether they are reasonable within the given constraints of time, budget, and other resources.
If it’s found that a requirement cannot be implemented due to one or more of these factors, then it should be discarded as it is not feasible and is therefore unnecessary from the start.
The design phase aims to create a detailed plan of how a product or service should run once it has been implemented. The key aim of this stage is to determine how work will be carried out and what the outcome should look like.
To ensure that each member of the team is working towards an overall common goal, the design stage should include a design document that records how a project will be carried out from start to finish.
This ensures that team members will have clear direction and can refer back to this plan to see what they are expected to achieve during each stage of development.
It’s important for everyone involved in a project to be aware of what is required to achieve the end goal.
This way, team members will know where they stand and how to go about completing their tasks in a way that fits with the designs and implementation of others.
Coding And Unit Testing
The coding stage refers to actually creating code for a particular project or product. This is where the different parts of a project which were designed in the previous stage will be brought together to create something useful.
The aim during this phase is for the team members to go through and implement the design documentation that was created at the beginning of development so that what has been planned can become a reality.
If everything goes according to plan during the development process, then it should be relatively straightforward for the team to make changes within a given project.
If this is not the case and some problems arise from the design stage which has not been anticipated or planned for in time, then it could become difficult to implement features or adapt according to how they should operate. This is why it’s important to go through each stage and ensure that everyone understands their role in a project so that they are clear on what work will be required from them during this stage of the Waterfall Model.
After that, they are doing unit testing to verify whether each model is working as expected or not.
Integration And System Testing
The integration stage is the next step once coding has been completed and it involves putting everything that was developed in the previous two stages together so that they function as one.
In this stage, team members should send their code to others within their given team who are working on different aspects of a project so that all of them can check whether their individual code is compatible with the rest of the team’s.
If all goes according to plan during this stage, then every aspect should work together as a whole and each section within what was designed during the design stage will be fully functional.
Once this has been verified, it will be relatively easy for developers to create patches where necessary and implement new features or adapt existing ones.
System testing is the next step after development and it involves putting a finished product through its paces to check whether it works as expected.
It’s vital for this stage that all team members involved are familiar with what has been developed within other sections so that they can test them together rather than in isolation. This will make it easier to ensure that individual components fit together and work as a whole.
If any bugs or problems are found at this point, then they can be fixed before the product reaches completion and is sent out to customers or clients so that they start using it. If there are serious issues with what has been created, then the project could be put on hold so that they can be fixed and development can continue in time for release.
This is the final stage of the Waterfall Model and it aims to take a fully functioning product or project which has been created through coding, integration, and system testing and get it ready for launch.
If developers have taken advantage of everything that can be done during this stage, then they should be able to run tests on how well a product or service works and get it ready for release.
Once they have done this, deployment is just a matter of getting the finished product out there so that users can start to make use of what has been created. This will not only show whether development has been successful but will also be an indicator of how much time has passed from the beginning of development until a completed product is released.
If everything goes to plan during this part of the Waterfall Model, then deployment will be relatively straightforward and the time it takes for a project to reach this stage should be relatively short compared to other models such as Agile.
However, if some problems or issues arise during the previous three stages, then deployment could be delayed until they have been fixed and this will slow down how quickly a project can be completed.
Once a project has been deployed and is being used by customers or clients, then further development must continue but at a much lower level.
There will likely be fixes with bugs or problems that occur in the software so that they can be dealt with quickly. Furthermore, new features and additions may be required overtime to meet the changing needs of customers and clients so that they can get more out of their products or services.
It’s common for projects to enter maintenance through a set of checkpoints but this shouldn’t cause too many problems as long as they’re recognized quickly and dealt with properly.
If these issues are resolved properly, then it’s likely that further growth can be achieved through this maintenance cycle. However, if they aren’t dealt with quickly enough, then it could be detrimental to the future of a project and could reduce customer satisfaction over time.
Pros & Cons of Waterfall Model
Next, we will talk about the Pros & Cons of the Waterfall Model as there are many discussions on both sides of the argument. It will help you understand why some developers still use Waterfall Model for building their projects.
The first benefit of the Waterfall Model is that it can be a good way to ensure quality work is being done because if development hasn’t been done properly or there are issues with it, then this will be picked up and fixed as part of the system testing stage. Once a product has reached completion and is ready for deployment, then it should be fully functional and almost ready to go. This can be beneficial if it’s being introduced into a market that’s already saturated with products or services and makes it easier to stand out from the crowd quickly.
The main problem with the Waterfall Model is that you won’t be able to determine a project’s costs from the start. This can be problematic as it means that managers or clients may not know how much they’re prepared to spend on a project and will have no way of knowing if it meets their requirements until after some time has passed. It’s also hard to judge when a project is going to end because the time between each stage can vary depending on many factors and this makes it difficult to set deadlines for when a project will be completed.
Furthermore, if there are issues with the previous stages that arise later on in development or testing, then it could delay deployment significantly because these problems would have to be resolved first before any work could continue. If these issues are not resolved quickly enough, then it could harm any future growth that a project or business may want to achieve.
Waterfall Model vs Agile
Next, we’ll talk about the differences between Waterfall and Agile.
Agile: The main difference between these two models is that Agile is more flexible than Waterfall in terms of how it’s implemented as well as how projects are carried out. It also has a shorter duration and this means that changes can be made more quickly and there’s less time for problems to get out of hand.
Agile also has a lower risk of issues arising during the project because testing is continuous, so it reduces the risk that functionalities will be either missing or work incorrectly. As well as this, Agile tends to offer greater flexibility in terms of how changes are implemented throughout development because it’s easier to react to any changes that occur and they can be implemented quickly.
It’s also less costly than Waterfall because iterations are used so the investment cost is spread out over a longer period of time. This means that it’s more affordable for both developers and clients as developers don’t have to spend large amounts of money upfront on a project and clients don’t have to wait until everything is finished before they can see their product.
However, Agile does have its disadvantages because there are fewer stages involved in development compared to Waterfall so it’s harder to estimate the overall cost of a project. It also relies heavily on continuous testing which can cause issues if tests aren’t carried out effectively, which can lead to unexpected consequences further down the line.
Waterfall: The main difference between Waterfall and Agile is that Waterfall involves many stages where products are tested after each stage is completed whereas, in Agile, testing occurs throughout the project because there are many smaller deliverables produced on an ongoing basis.
Waterfall also has a longer duration than Agile which means that there’s more time for issues and problems to occur. However, this does mean that Waterfall is more thorough as it allows more time for aspects to be checked thoroughly so the final product tends to be of a better quality overall.
Costs are relatively similar between these two models and both tend to be more expensive than if you were to use a custom software development company as they can produce bespoke products that will suit your needs exactly.
However, Waterfall does have the disadvantage of requiring large upfront costs which mean that it’s far riskier for developers and clients alike because there isn’t any flexibility in terms of changes and the only option is to spend more money or take a risk on whether or not any issues can be resolved.
This blog post was all about the waterfall model, a popular software development process used to define the technical approach and implementation method for developing and maintaining complex software systems. We hope you’ve learned something new today by reading this article! If there are any other questions or comments we can help with, please don’t hesitate to reach out in our comment section below.