Iterative Waterfall Model - Software Engineering

In a practical software development project, the classical Waterfall Model is hard to use. So, the Iterative Waterfall Model can be thought of as incorporating the necessary changes to the classical Waterfall Model to make it usable in practical software development projects. It is almost the same as the classical Waterfall Model, except some changes are made to increase the efficiency of the software development.

What is the Iterative Waterfall Model?

The Iterative Waterfall Model is a software development approach that combines the sequential steps of the traditional Waterfall Model with the flexibility of iterative design. It allows for improvements and changes to be made at each stage of the development process, instead of waiting until the end of the project. The Iterative Waterfall Model provides feedback paths from every phase to its preceding phases, which is the main difference from the classical Waterfall Model. 

1. When errors are detected at some later phase, these feedback paths allow for correcting errors committed by programmers during some phase.
2. The feedback paths allow the phase to be reworked in which errors are committed and these changes are reflected in the later phases.
3. Although the feasibility study phase doesn’t usually get frequent feedback, the iterative nature of this model allows for revisiting and updating it if new requirements or changes in technology come up later. This helps keep the project aligned with its goals throughout development.
4. It is good to detect errors in the same phase in which they are committed.
5. It reduces the effort and time required to correct the errors. 
6. A real-life example could be building a new website for a small business.

Process of Iterative Waterfall Model

Following are the phases of Iterative Waterfall Model:

1. Requirements Gathering: This is the first stage where the business owners and developers meet to discuss the goals and requirements of the website.
2. Design: In this stage, the developers create a preliminary design of the website based on the requirements gathered in stage 1.
3. Implementation: In this stage, the developers begin to build the website based on the design created in stage 2.
4. Testing: Once the website has been built, it is tested to ensure that it meets the requirements and functions properly.
5. Deployment: The website is then deployed and made live to the public.
6. Review and Improvement: After the website has been live for a while, the business owners and developers review its performance and make any necessary improvements.

This process is repeated until the website meets the needs and goals of the business. Each iteration builds upon the previous one, allowing for continuous improvement and iteration until the final product is complete.

When to use Iterative Waterfall Model?

1. The prerequisite of being well-defined and comprehended.
2. The development team is gaining knowledge about new technologies.
3. Certain characteristics and objectives carry a significant chance of failure in the future.

Application of Iterative Waterfall Model

Below are some application of Iterative Waterfall Model:

1. The essential needs are established, but as time passes, the finer points may become relevant.
2. Programmers have a learning curve to climb when they utilize new technology.
3. The resources needed to complete a large project are constrained, hence on a smaller scale, the automation is more temporary.
4. Very high risk as the project's objective may occasionally alter.

Why is iterative waterfall model used?

The main reason behind using iterative waterfall model is feedback path. While the feedback loop in the iterative waterfall model primarily focuses on later phases, it’s still possible to revisit the feasibility study if changes in requirements or technology emerge, ensuring the project stays aligned with its goals.

Advantages of Iterative Waterfall Model

Following are the advantage of Iterative Waterfall Model:

1. Phase Containment of Errors: Errors are detected and fixed as close to their source as possible, reducing costly rework and delays.
2. Collaboration: Continuous collaboration between business owners and developers ensures the product meets business needs and improves with feedback at each iteration.
3. Flexibility: The model allows for easy incorporation of new requirements or features in subsequent iterations, ensuring the product evolves with the business.
4. Testing and Feedback: Regular testing and feedback cycles help identify and fix issues early, improving the product's quality and relevance.
5. Faster Time to Market: Incremental development allows parts of the product to be delivered sooner, enabling user feedback while further improvements are made.
6. Risk Reduction: Continuous feedback and testing help identify risks early, reducing the likelihood of costly errors and delays.

Drawbacks of Iterative Waterfall Model

Following are the disadvantage of Iterative Waterfall Model:

1. Difficult to incorporate change requests: The major drawback of the iterative waterfall model is that all the requirements must be clearly stated before starting the development phase. Customers may change requirements after some time but the iterative waterfall model does not leave any scope to incorporate change requests that are made after the development phase starts. 
2. Incremental delivery not supported: In the iterative waterfall model, the full software is completely developed and tested before delivery to the customer. There is no scope for any intermediate delivery. So, customers have to wait a long for getting the software. 
3. Overlapping of phases not supported: Iterative waterfall model assumes that one phase can start after completion of the previous phase, But in real projects, phases may overlap to reduce the effort and time needed to complete the project. 
4. Risk handling not supported: Projects may suffer from various types of risks. But, the Iterative waterfall model has no mechanism for risk handling. 
5. Limited customer interactions: Customer interaction occurs at the start of the project at the time of requirement gathering and at project completion at the time of software delivery. These fewer interactions with the customers may lead to many problems as the finally developed software may differ from the customers' actual requirements. 

Conclusion

The Iterative Waterfall Model is an improved version of the traditional Waterfall Model, combining the structured, sequential approach of Waterfall with the flexibility of iterative cycles. Unlike the classical Waterfall, which progresses linearly, the Iterative Waterfall Model allows for revisions and feedback at each phase, enabling early detection and correction of errors. This iterative process leads to a refined and reliable final product. It enhances project management, encourages collaboration, and allows for continuous improvement, ensuring that the software meets evolving business needs while minimizing risks and costs.