Non-Functional Requirements

Definition

Non-functional requirements refer to the criteria that define the quality and performance attributes of a system, rather than specific functionalities or behaviors. They are crucial for determining how well a system performs its functions, focusing on aspects like usability, reliability, performance, and security. Understanding non-functional requirements is essential for gathering comprehensive system requirements and creating effective designs that meet user expectations and operational needs.

5 Must Know Facts For Your Next Test

1. Non-functional requirements can greatly impact user satisfaction and acceptance of a system, as they often dictate the overall user experience.
2. These requirements include categories like performance, security, maintainability, scalability, and compliance.
3. Gathering non-functional requirements often involves stakeholder interviews and surveys to ensure all user needs are captured.
4. In system design, non-functional requirements inform architectural decisions and help prioritize features based on their impact on performance.
5. Failure to adequately define or address non-functional requirements can lead to project failures, costly revisions, or user dissatisfaction.

Review Questions

• How do non-functional requirements influence the process of gathering system requirements?
  • Non-functional requirements play a vital role in gathering system requirements because they help define the overall quality attributes that the system must meet. During this phase, stakeholders express their needs not only in terms of what the system should do but also how it should perform under various conditions. This ensures a more holistic view of user expectations and leads to a more comprehensive understanding of both functional and non-functional needs.
• Discuss the importance of non-functional requirements in the design and modeling phase of system development.
  • In the design and modeling phase, non-functional requirements are critical as they guide architects and developers in creating systems that not only meet functionality but also perform optimally in real-world scenarios. By addressing aspects such as scalability, security, and usability early in the design process, teams can avoid costly redesigns later. Non-functional requirements influence technical decisions regarding infrastructure choices, design patterns, and technology stacks to ensure the final product aligns with user expectations.
• Evaluate the consequences of neglecting non-functional requirements in software development projects.
  • Neglecting non-functional requirements can lead to significant issues in software development projects. When these criteria are overlooked, systems may fail to perform adequately under load or become difficult to use, ultimately leading to poor user adoption. Additionally, inadequate focus on security can expose systems to vulnerabilities, risking data breaches. Such oversights not only impact immediate project success but can also tarnish an organization's reputation and lead to financial losses due to necessary rework or remediation efforts.

Related terms

Functional Requirements:

Specifications that describe what a system should do, outlining the specific behaviors and functions required by users.

Usability:

A measure of how easy and satisfying a system is for users to interact with, which falls under non-functional requirements.

Performance Metrics: Quantifiable measures used to evaluate the performance of a system, such as response time, throughput, and resource utilization.