When are requirements specified for the waterfall model?

What Is the Waterfall Model?

The waterfall model is one of the simplest software development models used by software development teams. It is among the earliest models used in software development and is known as a highly rigid and structured model. The waterfall model works on the presumption that the project’s requirements are fairly clear and will not change throughout development. The process is divided into several stages, which need to be accomplished strictly and sequentially. These phases include:

• Requirements gathering and analysis: The first part of the project is when all the demands are gathered and assessed.
• System design: The system plan is developed in accordance with the collected specifications.
• Implementation: This is the step where coding or development of the system physically occurs.
• Testing: In this step, the functionality of each system component is checked to confirm that it functions in the intended way.
• Deployment: The system is delivered to the customer, or rather, the end-user is provided with the system.
• Maintenance: After deployment, the system is then managed and upgraded from time to time if necessary.

When Are Requirements Specified in the Waterfall Model?

In the waterfall model, requirements are specified during the very first phase, which is requirements gathering and analysis. This phase is the cornerstone of the entire process, as the decisions made here influence every subsequent phase.

1. Initial Documentation

During the initiation phase, the stakeholders and the project team come together and capture all the intended and implicit characteristics of the system. This documentation is quite elaborate, and developers rely on this throughout the project. The requirements must be precise, unambiguous, and shared between the parties involved in the system development.

2. Comprehensive Analysis

The requirements are then reviewed to identify their potential and how they will be met in the designing and developing phase. It involves activities such as the detection of risks, the definition of the project boundaries, and the prioritization of requirements.

3. Validation of Requirements

After the initial analysis, the requirements are validated against the project’s objectives and constraints. This validation ensures that all requirements align with the business goals and are technically feasible. It also helps identify gaps or inconsistencies that may have been overlooked during the initial documentation phase.

4. Approval and Sign-off

Following the analysis, the document will be shared with stakeholders to clarify any confusion and for the final sign-off. This sign-off is important because, after it, the team will proceed directly to design with the clear understanding that the requirements will not change.

Importance of Specifying Requirements Early

The early specification of requirements in the Waterfall Model is essential for several reasons:

• Predictability: The outcome of each step can be predicted since everyone clearly understands what will be delivered at the end of each phase of the project.
• Structured approach: Having a clear list of requirements is convenient because it helps plan the next stages.
• Risk management: Early requirement analysis allows us to notice some of the risks and difficulties that may be encountered in the later stages of the project.
• Customer satisfaction: Clear requirements are critical in ensuring the end product satisfies the customer. There is no confusion on expectations, and hence, there is hardly any dissatisfaction at the end of the project.

Challenges of Early Specification

Although there are several advantages of specifying requirements early, the waterfall method also comes with some challenges due to early requirement specification:

• Once the requirements are set, it’s difficult to make changes without causing problems.
• Since the process is linear, you don’t get much chance to fix issues or improve earlier steps based on what you learn later.
• Requirements can become outdated if the project duration is long.
• It is inflexible compared to new methods like Agile, kanban, etc.

Conclusion

In the waterfall method, requirements are defined in the initial stage, which is requirements gathering and analysis. This early requirement-defining process has both advantages and disadvantages. For example, this approach will work perfectly for It works projects with straightforward and stable requirements. However, the waterfall method might not be the perfect match for projects with changing requirements.