Prototyping Model

The prototyping model assumes that you do not have clear requirements at the beginning of the project. Often, customers have a vague idea of the requirements in the form of objectives that they want the system to address. With the prototyping model, you build a simplified version of the system and seek feedback from the parties who have a stake in the project. The next iteration incorporates the feedback and improves on the requirements specification. The prototypes that are built during the iterations can be any of the following:

• A simple user interface without any actual data processing logic
• A few subsystems with functionality that is partially or completely implemented
• Existing components that demonstrate the functionality that will be incorporated into the system

The prototyping model consists of the following steps.

1. Capture requirements. This step involves collecting the requirements over a period of time as they become available.
2. Design the system. After capturing the requirements, a new design is made or an existing one is modified to address the new requirements.
3. Create or modify the prototype. A prototype is created or an existing prototype is modified based on the design from the previous step.
4. Assess based on feedback. The prototype is sent to the stakeholders for review. Based on their feedback, an impact analysis is conducted for the requirements, the design, and the prototype. The role of testing at this step is to ensure that customer feedback is incorporated in the next version of the prototype.
5. Refine the prototype. The prototype is refined based on the impact analysis conducted in the previous step.
6. Implement the system. After the requirements are understood, the system is rewritten either from scratch or by reusing the prototypes. The testing effort consists of the following:
   • Ensuring that the system meets the refined requirements
   • Code review
   • Unit testing
   • System testing

The main advantage of the prototyping model is that it allows you to start with requirements that are not clearly defined.

The main disadvantage of the prototyping model is that it can lead to poorly designed systems. The prototypes are usually built without regard to how they might be used later, so attempts to reuse them may result in inefficient systems. This model emphasizes refining the requirements based on customer feedback, rather than ensuring a better product through quick change based on test feedback.