Non-Functional Requirements (5 IIBA® PDUs)

Define availability by specifying when, where, and for how long a solution must be accessible, considering user context and devices, with graceful degradation and maintenance windows.

Learn to quantify availability using the time-based formula and SLA-driven targets, including high availability concepts, hours of operation refinements, and defining web and non-web system and client requirements.

Explore availability targets in vendor SLAs, compare 99.95% availability and service credits, and connect these requirements to browser, device, OS portability and system requirements.

Define maintainability as the ease of restoring operation after failure and set targets; measure baseline metrics and use them to drive continuous improvement with availability, reliability, and downtime considerations.

Quantify maintainability using metrics like mean time to recover and mean time between failures. Improve availability through diagnosis, repair, and monitoring practices.

Examine how maintainability requirements leverage reliability principles, separating principles from measurable targets, with examples from Energex and Ergon Energy and Telstra to show regulatory metrics and regulator-defined availability targets.

Explore how availability, reliability, and maintainability support business continuity while detailing recovery time objective and recovery point objective, backups, and manual workarounds.

Explore a case study of business continuity during the WannaCry ransomware attack, highlighting how hospitals relied on manual processes, paper-based workarounds, and basic clinical procedures to stay operational.

Define compatibility requirements to ensure systems coexist and exchange data without conflicts. Learn about backward and forward compatibility, environments, dependencies, and how to build interoperability.

Define compatibility by listing all the versions and systems your solution should work with, so it can be built and tested against clear requirements.

Explore the Android compatibility program, its definition document, and test suite, and why compatibility matters for users to support customizable devices, third-party developers, and a common ecosystem.

Define capacity and performance by examining how much load a solution can handle, including concurrent users and transactions per second, then set acceptable response times.

Explore how performance testing quantifies stability, speed, and scalability through load, stress, and endurance tests, using baselining, monitoring, and tools like JMeter to set measurable requirements.

Apply a quick performance check using Google Lighthouse to assess baseline metrics like first contentful paint, largest contentful paint, total blocking time, and speed index before scaling to full tests.

Explore security requirements grounded in the CIA triad—confidentiality, integrity, and availability—covering information classification, access control, separation of duties, and regulatory compliance.

Quantify security requirements by aligning with established frameworks such as ISO 27001, NEST, GDPR, HIPAA, and PCI, and validate through penetration testing.

Explore the OWASP Top 10 vulnerabilities, their evolution, and the how to prevent requirements, with attack scenarios for security testing and guidance on addressing common weaknesses.

Design accessible products by addressing diverse impairments—auditory, cognitive, neurological, physical, speech, and visual—and consider temporary, situational, and age-related needs to widen reach and improve user experience.

Quantifying accessibility by applying WCAG 2.2 requirements—perceivable, operable, understandable, robust; assess with automated and manual audits, including color contrast and screen reader considerations.

Perform accessibility testing with a tool like accessibility checker.org to reveal issues such as misordered headings and non-descriptive links, and emphasize manual audits for keyboard focus and alt text.

Explore usability requirements as a bridge between accessibility and user experience, covering learnability, memorability, efficiency, error prevention, and satisfaction, plus practical usability testing.

Case study of Apple's 1982 usability guidelines reveals how user research, human-centered design, and usability testing shape simple, efficient interfaces.

Audit requirements cover preserving logs to investigate incidents and demonstrate compliance. Define what to log with meaningful metadata, severity levels, and references, and align with regulatory and monitoring needs.

Explores a university login standards document, detailing logging requirements for authentication, authorization, and access changes; defines log elements, formatting, central monitoring, privacy, and retention practices.