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. But, there is no feedback path to the stage – feasibility study, because once a project has been taken, does not give up the project easily. 
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

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

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. In the classical waterfall model, there are no feedback paths, so there is no mechanism for error correction. But in the iterative waterfall model feedback path from one phase to its preceding phase allows correcting the errors that are committed and these changes are reflected in the later phases.

Advantages of Iterative Waterfall Model

1. Phase Containment of Errors: The principle of detecting errors as close to their points of commitment as possible is known as Phase containment of errors. 
2. Collaboration: Throughout each stage of the process, there is collaboration between the business owners and developers. This ensures that the website meets the needs of the business and that any issues or concerns are addressed in a timely manner.
3. Flexibility: The iterative waterfall model allows for flexibility in the development process. If changes or new requirements arise, they can be incorporated into the next iteration of the website.
4. Testing and feedback: The testing stage of the process is important for identifying any issues or bugs that need to be addressed before the website is deployed. Additionally, feedback from users or customers can be gathered and used to improve the website in subsequent iterations.
5. Scalability: The iterative waterfall model is scalable, meaning it can be used for projects of various sizes and complexities. For example, a larger business may require more iterations or more complex requirements, but the same process can still be followed.
6. Maintenance: Once the website is live, ongoing maintenance is necessary to ensure it continues to meet the needs of the business and its users. The iterative waterfall model can be used for maintenance and improvement cycles, allowing the website to evolve and stay up-to-date.
7. Easy to Manage: The iterative waterfall model is easy to manage as each phase is well-defined and has a clear set of deliverables. This makes it easier to track progress, identify issues, and manage resources.
8. Faster Time to Market: The iterative approach allows for faster time to market as small and incremental improvements are made over time, rather than waiting for a complete product to be developed.
9. Predictable Outcomes: The phased approach of the iterative waterfall model allows for more predictable outcomes and greater control over the development process, ensuring that the project stays on track and within budget.
10. Improved Customer Satisfaction: The iterative approach allows for customer involvement and feedback throughout the development process, resulting in a final product that better meets the needs and expectations of the customer.
11. Quality Assurance: The iterative approach promotes quality assurance by providing opportunities for testing and feedback throughout the development process. This results in a higher-quality end product.
12. Risk Reduction: The iterative approach allows for early identification and mitigation of risks, reducing the likelihood of costly errors later in the development process.
13. Well-organized: In this model, less time is consumed on documenting and the team can spend more time on development and designing.
14. Cost-Effective: It is highly cost-effective to change the plan or requirements in the model. Moreover, it is best suited for agile organizations.
15. Simple: Iterative waterfall model is very simple to understand and use. That’s why it is one of the most widely used software development models.
16. Feedback Path: In the classical waterfall model, there are no feedback paths, so there is no mechanism for error correction. But in the iterative waterfall model feedback path from one phase to its preceding phase allows correcting the errors that are committed and these changes are reflected in the later phases.

Drawbacks 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.