Iterative Waterfall Model is the extension of the Classical Waterfall model in the Software Development Life Cycle (SDLC). In a practical software development work, it is not possible to strictly follow the classical waterfall model. The Iterative Waterfall Model is an adaptation of the traditional Waterfall Model that incorporates iterative processes into the linear framework of the original model. Iterative model is almost same as the classical waterfall model except some changes are made to improve the performance of the software development. It introduces the possibility of revisiting and refining earlier stages, allowing feedback and changes after each iteration. This makes it more flexible compared to the rigid linear approach of the traditional waterfall model.
The iterative waterfall model provides feedback paths from every phase to its previous phases, which is the main difference from the classical waterfall model. When errors are detected at some later phase, these feedback paths allow correcting errors committed by programmers during some phase. The feedback path allows the phase to be reworked in which errors are committed and these changes are reflected in the later phases. There is no feedback path provided for feasibility study phase, so if any change is required in this phase then iterative model doesn’t have scope for modification or making corrections.
The Iterative Waterfall Model combines the structured approach of the traditional Waterfall Model with the flexibility of iterative development. It is particularly useful in projects where requirements may evolve over time or where user feedback is critical to the success of the project. By allowing for adjustments and refinements throughout the development process, this model aims to deliver a product that better meets user needs while still maintaining a clear and organized development framework.
Feedback paths introduced by the iterative waterfall model are shown in the figure below.Â
Key Features:
- Iterative Phases: Unlike the classical Waterfall Model, where each phase is completed before moving to the next, the Iterative Waterfall Model allows for revisiting and refining earlier phases based on insights gained during later phases. This means that after testing, for example, developers can go back to the requirements or design phases to make necessary adjustments.
- Feedback Loops: The model incorporates feedback loops that enable teams to gather input from users and stakeholders at various stages, leading to better alignment with user needs and expectations.
- Sequential but Iterative: The phases are still followed sequentially, but iterations allow revisiting previous stages based on feedback or new insights.
- Risk Management: By allowing for iterations, the model helps identify and mitigate risks earlier in the development process. Issues can be addressed as they arise, rather than waiting until the end of the project.
Phases of the Iterative Waterfall Model:
The phases in the Iterative Waterfall Model are similar to those in the classical Waterfall Model, but with the added flexibility of iteration:
Requirement Analysis:
- Gather and document requirements. This phase may involve multiple iterations to refine and clarify requirements based on stakeholder feedback.
System Design:
- Create the system architecture and design. This phase can also be revisited as new requirements emerge or existing ones change.
Implementation (Coding):
- Writing the source code based on the design documents.
- If issues are found during testing, the code can be modified in the next iteration.
Integration and Testing:
- Integrating modules and performing thorough testing.
- Feedback from testing can lead to revisiting earlier phases to address issues or enhance features.
Deployment:
- Deploying the working product.
- Feedback from deployment or user experience can lead to changes in requirements or design.
Maintenance:
- Ongoing support, updates, and bug fixes.
- Feedback from maintenance can be used to start another iteration.
Advantages:
Flexibility: Allows modifications at any stage, reducing the risk of project failure. The ability to revisit earlier phases allows for adjustments based on feedback, making the process more adaptable to changing requirements.
Early Bug Detection: Issues can be identified and fixed earlier through iterative testing, reducing the risk of major problems later in the project.
User Feedback: Feedback from users or stakeholders can be incorporated in the next iteration, improving product quality. Continuous feedback from users and stakeholders helps ensure that the final product aligns with their needs and expectations.
Disadvantages:
Complexity in Management: Managing multiple iterations and versions can be challenging. Managing iterations can add complexity to project management, requiring careful planning and coordination.
Higher Costs: Repeated testing and iteration cycles can increase the overall cost and time.
Documentation Challenges: While documentation is still important, the iterative nature may lead to challenges in maintaining up-to-date documentation across iterations.
When to Use:
- When requirements are not well understood or likely to evolve.
- In complex projects where risk management and feedback are critical.
- When the project is large-scale, requiring regular feedback and gradual improvements.