Non-functional requirements

Definition

Non-functional requirements refer to the criteria that judge the operation of a system, rather than the specific behaviors or functions it performs. They encompass aspects such as performance, security, usability, and reliability, which are crucial for the overall quality and user satisfaction of a system. These requirements help to set the standards for how well a system should perform its intended functions in real-world scenarios.

5 Must Know Facts For Your Next Test

1. Non-functional requirements often define constraints within which the functional requirements must operate, affecting design and implementation choices.
2. They are typically prioritized alongside functional requirements during project planning to ensure they receive adequate attention throughout development.
3. Non-functional requirements can be more challenging to test and validate compared to functional requirements due to their subjective nature.
4. Examples include performance metrics like response time, availability levels, scalability needs, and compliance with regulations or standards.
5. Incorporating non-functional requirements early in the project planning process can help avoid costly changes later in development or after deployment.

Review Questions

• How do non-functional requirements differ from functional requirements in a project?
  • Non-functional requirements focus on how a system operates rather than what it does. While functional requirements specify the tasks the system must perform, such as user interactions or data processing, non-functional requirements address the system's performance, usability, security, and other qualities. Understanding this distinction is crucial during project planning because both sets of requirements contribute to user satisfaction and system effectiveness.
• Discuss how prioritizing non-functional requirements during project planning can impact the development process.
  • Prioritizing non-functional requirements during project planning can lead to better alignment between user expectations and the final product. By addressing factors like performance and security upfront, developers can make informed design decisions that avoid rework later in the process. This proactive approach helps ensure that systems are not only functional but also reliable and efficient in real-world use, ultimately contributing to project success.
• Evaluate the potential consequences of neglecting non-functional requirements when analyzing project needs.
  • Neglecting non-functional requirements can lead to significant negative outcomes for a project. For instance, if performance issues are overlooked, users may experience slow response times that degrade their experience. Similarly, ignoring security measures could result in vulnerabilities that expose sensitive data. These oversights can cause user dissatisfaction and may necessitate extensive revisions post-deployment, increasing costs and potentially harming the project's reputation.

Related terms

functional requirements: Functional requirements describe what a system should do, outlining specific behaviors and functions that the system must support.

system architecture: System architecture refers to the high-level structure of a system, defining its components and their relationships, which can influence both functional and non-functional requirements.

quality attributes: Quality attributes are characteristics that affect the quality of a system, including non-functional aspects like performance, security, and maintainability.