What are Non-functional Requirements and How Do They Work?

Summary

This video explores the distinction between functional and non-functional requirements in software development. Functional requirements define what a product should do, such as user actions in an app, while non-functional requirements specify how those actions should perform, focusing on qualities like performance and security. The video highlights the importance of both types, providing insights into documenting them effectively through user stories and acceptance criteria, and emphasizes the need for measurable metrics to ensure quality during testing. By understanding these concepts, developers can create applications that not only meet user needs but also excel in performance and usability.

Takeaways

• 😀 Non-functional requirements define how a product should perform, complementing functional requirements which specify what it should do.
• 😀 Non-functional requirements are crucial for user satisfaction, impacting aspects like performance, usability, and security.
• 😀 Functional requirements can be illustrated through user stories, detailing specific tasks users should accomplish within an application.
• 😀 Non-functional requirements are typically derived from product goals, competitor analysis, and existing technology constraints.
• 😀 It's important to document non-functional requirements as part of acceptance criteria to ensure that products meet performance standards.
• 😀 Metrics and testing are essential for evaluating non-functional requirements, helping to quantify attributes like scalability and security.
• 😀 Non-functional testing often involves automated tests to efficiently assess critical application properties.
• 😀 Non-functional requirements can affect multiple attributes simultaneously, making them complex but essential for overall application quality.
• 😀 Focusing on specific components for non-functional requirements can simplify the process and improve manageability.
• 😀 Existing standards and guidelines can provide valuable insights when defining non-functional requirements, leveraging prior knowledge and experience.

Q & A

What are functional requirements?

Functional requirements specify what a product should do, detailing user actions and features within the application.

Can you give an example of a functional requirement?

An example of a functional requirement for a social media app would be the ability for users to create a personal profile.

What are non-functional requirements?

Non-functional requirements describe how a product should perform its functions, focusing on quality attributes such as performance and security.

How do non-functional requirements differ from functional requirements?

While functional requirements outline what a product does, non-functional requirements focus on how well it performs those functions.

Why are non-functional requirements important?

They are crucial for defining the quality and performance expectations of a product, impacting user satisfaction and overall product effectiveness.

What are some common examples of non-functional requirements?

Common examples include performance, scalability, usability, security, and maintainability.

How can non-functional requirements be documented?

They can be documented in the definition of done section linked to user stories, detailing expectations for performance and other quality metrics.

What role do metrics play in non-functional requirements?

Metrics are essential for measuring and testing non-functional requirements, helping to ensure that the product meets its quality standards.

What is non-functional testing?

Non-functional testing involves assessing attributes like performance, scalability, and security, often using automated methods to save time and ensure quality.

What should developers consider when defining non-functional requirements?

Developers should link requirements to business objectives, focus on specific components, and refer to existing standards and guidelines.