Non-Functional Requirements
Non-functional requirements describe the quality attributes, constraints, and performance standards a solution must meet, specifying how well the system should perform rather than what it should do.
Explanation
Non-functional requirements define the conditions under which a solution must operate and the quality standards it must achieve. They address attributes such as performance (response time, throughput), reliability (uptime, mean time between failures), scalability (concurrent users, data volume), security (authentication, encryption), usability (accessibility, learnability), and maintainability.
These requirements are often more difficult to elicit than functional requirements because stakeholders may assume certain quality levels without explicitly stating them. The business analyst must proactively ask about performance expectations, security constraints, compliance requirements, and scalability needs. Non-functional requirements are typically documented alongside functional requirements but may also appear in a separate quality requirements section.
Non-functional requirements are critical because they significantly impact solution architecture and design decisions. A system that meets all functional requirements but fails non-functional ones (such as being too slow or unreliable) will not satisfy stakeholders. On the CAPM exam, you must be able to identify non-functional requirements and distinguish them from functional ones.
Key Points
- •Cover quality attributes: performance, reliability, scalability, security, usability, and maintainability
- •Describe how well the system performs, not what it does
- •Often implicit and must be proactively elicited from stakeholders
- •Significantly impact architecture and design decisions
Exam Tip
Non-functional requirements describe qualities and constraints. Look for keywords like "within X seconds," "99.9% availability," "support N concurrent users," or "comply with [standard]" to identify them.
Frequently Asked Questions
Related Topics
Functional Requirements
Functional requirements describe the specific behaviors, features, and capabilities a solution must provide, defining what the system should do in response to inputs or conditions.
Solution Requirements
Solution requirements describe the characteristics, features, and capabilities that a solution must possess to meet business and stakeholder requirements. They are divided into functional and non-functional requirements.
Stakeholder Requirements
Stakeholder requirements describe the needs of individual stakeholders or stakeholder groups, including what they need the solution to do for them in order to meet the business requirements.
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