Nonfunctional requirement
A nonfunctional requirement specifies a quality attribute, constraint, or operating condition that a system must satisfy beyond the particular functions it performs.
Delivering Machine Learning Projects: From design to deployment
A nonfunctional property describes an operational characteristic of data, such as its scale, speed, history, or update frequency.
- How it is used
- Constrains whether an ML solution can serve its business purpose within practical operating limits.
- How deep it goes
- Defines the constraint, identifies properties to capture and test, and carries them into production without specifying a benchmark protocol.
- Examples
- Uses a recommendation priced below $0.0001 and delivered within 200 ms, plus cold starts and parallel execution.
- What you can do after
- Practice/perform requirements capture with discovery tickets and story cards, then test candidate models against operational constraints.
Software Design for Python Programmers
A nonfunctional requirement is a requirement specifying a quality, constraint, or condition on how an application operates rather than a specific capability.
- How it is used
- Defines operational constraints that guide application requirements, use cases, specifications, and validation.
- How deep it goes
- Explains definition, categories, wording, elicitation, use-case context, and black-box verification, without prescribing implementation designs.
- Examples
- Uses search latency, operating-system support, interface similarity, and multilingual messages in a book-catalogue application.
- What you can do after
- Evaluate application success by stating observable constraints and verifying them through external black-box tests.
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Object-Oriented Software Design in C++
A requirement that imposes a constraint on an application's qualities, operation, environment, or implementation-independent behavior rather than specifying a discrete feature.
- How it is used
- Guides requirements gathering and application planning by constraining performance, platforms, maintainability, and practical functionality.
- How deep it goes
- Defines constraints, gives book-catalogue examples, and links them to use cases and black-box tests, but stops short of implementation design.
- Examples
- Uses book-search latency, operating-system support, interface similarity, and multilingual messages as concrete constraints.
- What you can do after
- Evaluate/understand application constraints and express them as strong, implementation-independent requirements that can be tested.
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Kafka for Architects
A non-functional requirement specifies a quality attribute, constraint, or operational characteristic of a system rather than a business function.
- How it is used
- Guides Kafka platform selection, cluster sizing, client tuning, cost estimates, and performance validation.
- How deep it goes
- Develops a requirements-gathering checklist for message size, latency, and throughput, then connects those targets to load testing.
- Examples
- Uses average and maximum message sizes, distinct latency stages, and a throughput scenario with daily volume, bursts, and backlog clearance.
- What you can do after
- Practice defining measurable Kafka operating targets and evaluating a configuration against them with performance tests.
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Functional Design and Architecture: Examples in Haskell
A nonfunctional requirement specifies general qualities or operational constraints of an application rather than specific functions.
- How it is used
- Frames application design around qualities and constraints beyond required functionality.
- How deep it goes
- Defines the category and distinguishes it from functional requirements through spacecraft properties and maintainability concerns.
- Examples
- Uses spacecraft reliability, fault tolerance, continuous operation, security, compatibility, capacity, and latency as examples.
- What you can do after
- Evaluate design goals by separating required behavior from qualities that constrain implementation and future maintenance.
Machine Learning System Design
A requirement that specifies qualities or operational constraints of a system, such as performance, security, or portability.
- How it is used
- Frames ML risks, system qualities, and operating constraints as requirements alongside feature functionality.
- How deep it goes
- Defines the functional distinction and applies it to risk modeling and operational concerns without detailing a complete requirements taxonomy.
- Examples
- Uses a real-time dynamic pricing system and concrete worst-case-risk questions to illustrate requirements.
- What you can do after
- Evaluate an ML system by identifying protections, operating connections, and constraints beyond its user-facing functionality.
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Related concepts
- requirementskind of · A requirement is a stated need, capability, quality, condition, or constraint that a system, product, solution, or project is expected to satisfy.
- functional requirementcontrasts with · A functional requirement specifies a behavior or capability that a system must provide or enable.
- scalabilityincludes · Scalability is the ability of a system, process, or method to accommodate increasing workload, size, or demand while maintaining acceptable operation.
- performanceincludes · Performance is the measurable effectiveness or operational behavior of a system under specified conditions, assessed through relevant qualities such as task results, speed, responsiveness, throughput, or resource use.
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