Waterfall Model in Software Engineering | Modified Waterfall Model

The Waterfall Model in Software Engineering is a well-known and widely used software development process that has been around for several decades. It was first introduced in the 1970s and has since become one of the most popular software development methodologies. In this article, we will discuss the classic and modified waterfall model in Software Engineering, the advantages, and disadvantages of waterfall model, and also discuss phases of the waterfall model. so let’s start

What is Waterfall Model?

The Waterfall model is a software development process that follows a linear and sequential approach. It involves a series of distinct phases that are completed one after another, with no overlapping of phases.

It was the first process model, introduced by Dr. Winston W. Royce and published in a paper titled “Managing the Development of Large Software Systems,” which was published in the Proceedings of IEEE WESCON in 1970.

In classic waterfall, when we complete one phase only then we can begin the next phase. The whole process is split into separate phases. These phases follow up in sequence one after the other. This means the whole process works like a waterfall means when water is falling then water cannot come back. As the same applies in this model, when any phase is complete then we cannot come back to the previous phase.

The classic waterfall model is also referred to as Linear-Sequential Life Cycle Model. This means the whole software is developed in a linear sequence means one phase to another face sequence-wise. This model is also referred to as a strict waterfall model because all the phases are strictly followed like a waterfall.

For example, once we enter in coding phase or testing phase then we can’t back to the design phase in the classic waterfall model.

Classic waterfall model


Advantages of the Classic Waterfall Model

One of the advantages of the classic waterfall model is that it provides a clear and straightforward framework for software development. Each stage is well-defined, and the process is easy to follow. This model is suitable for small and simple projects where the requirements are well understood and do not change frequently.

Drawbacks of Classic waterfall model

Classic waterfall model cannot be used to develop the actual software project because it is not a practical model, we can’t apply this model practically in software development. The main reason is once we complete one phase and move to the next phase then we can’t jump back to previous phases. That’s why we can’t use this model practically because today’s not possible, we can develop the software perfectly at once.

When we develop any software, there can be created many problems at the time of development as customer requirements change, customer wants new functionality or find some bugs in the testing phase, etc. That’s why we can’t use this model practically, we can understand this model theoretically but can’t be applied.

The biggest limitation is that it does not allow for feedback or changes during the development process. This can be a problem in real-world projects where requirements can change frequently.

Some points classic waterfall model disadvantages

  • Freezing the requirements.
  • Cannot go backward.
  • Poor model for long-duration projects.
  • High risk of failure.
  • Customers have little interaction with the software development team.
  • High amount of risk and uncertainty.

Some other models, you should read: Prototype Model, Incremental Model 


Modified Waterfall model

One of the main drawbacks of the classic waterfall model, once any problem is created at any particular phase in software development, there is no way to get back to an earlier stage to solve the problem.

So to overcome this drawback, the waterfall model has been modified to add a feedback system between stages. So that if any problem is found in one phase can cause remedial action to take in the previous phase.

The main difference between the classic and modified waterfall model is the feedback system, which provides to previous phases. If errors or problems are detected at any phase, this feedback system helps previous phases to correct errors or problems.

Modified waterfall model also referred to as the iterative waterfall model

modified waterfall model
modified waterfall model

You should read this article: What is SDLC (Software Development Life Cycle)

Advantages of the Modified Waterfall Model

The main advantage of the modified waterfall model is its flexibility. This allows software development teams to respond to changes in the market or changes in user requirements without significantly impacting the project timeline. The modified approach also reduces the likelihood of errors and increases the quality of the final product.

Disadvantages of the Modified Waterfall Model

One of the disadvantages of the modified waterfall model is that it can be more difficult to manage than the classic approach. The modified approach requires more frequent communication and collaboration between team members to ensure that changes are incorporated correctly. Additionally, the modified approach can be less predictable, making it harder to estimate project timelines and budgets accurately.


Phases in waterfall model

Requirement Gathering and Analysis – In this phase, the project requirements are gathered from stakeholders and a requirements document is created. This document serves as the basis for the rest of the project. We collect all the software requirements from the customer through discussion and interviews and write in a document called SRS document (Software Requirement Specification document). This SRS document is the base of the software project because this document helps to develop the whole software project.

System Design – In this phase, the system design is created based on the requirements document. This includes creating detailed specifications for the system and its components. It is the process where we define system architecture, components, modules, interface, and data of a system using the requirement specification documents.

Implementation – In this phase, system design is used to develop the system, the system is first developed in small programs called units. This is a coding phase, where programmers start to develop the system by writing code using the programming language. They already decided which language they use for developing the system.

Integration and Testing – In this phase, the testing team runs our software and check whether the software gives us the desired result or not.

Deployment of system − Once the testing is done, the product is deployed in the customer environment or released into the market.

Maintenance – Maintenance is the backbone of software success. When software is developed, then the software needs to be modified from time to time to keep it up to date with environmental changes and changing user requirements.


Frequently Asked Questions of Waterfall Model


Why is the Waterfall Model still used today?

Although the Waterfall Model is an older software development methodology, it is still widely used today. One of the reasons for this is that it is a straightforward and easy-to-understand process. It is also beneficial for projects where the requirements are well-defined and unlikely to change. Additionally, it provides a clear set of deliverables for each phase, making it easier to manage and track progress.

When is the Waterfall Model used?

The Waterfall Model is typically used in small, simple projects where the requirements are well understood and do not change frequently.

Can the Waterfall Model be used in large and complex projects?

The Waterfall Model can be used in large and complex projects, but it may not be the most suitable approach. Large and complex projects often involve changing requirements, multiple teams, and a high level of coordination, which can be difficult to manage with a linear and sequential approach.

How does the Waterfall Model handle testing?

Testing is a separate phase in the Waterfall Model, which occurs after the construction phase. This means that testing occurs after the software has been built, which can result in defects being discovered late in the process. This can be time-consuming and expensive to fix, as it may require going back to previous phases.


Some other models, you should read:

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