Functional requirement
A functional requirement specifies a behavior or capability that a system must provide or enable.
Delivering Machine Learning Projects: From design to deployment
A functional requirement specifies a capability or behavior that a system must provide.
- How it is used
- Specifies the ML capability a proposed system must deliver for users and business value.
- How deep it goes
- Defines inputs and required outputs, then develops viable concepts into stories and story cards; defers fuller implementation detail until the project proceeds.
- Examples
- Uses a book recommendation with profile, budget, and date as inputs, alongside separate cost and response-time limits.
- What you can do after
- Evaluate/understand whether a proposed ML capability has defined inputs and outputs, a feasible path to delivery, and a usable business result.
Software Design for Python Programmers
A functional requirement is a requirement specifying an operation that an application must perform or enable a user to perform.
- How it is used
- Guides discovery, specification, validation, and early design by stating the behavior an application must provide.
- How deep it goes
- Explains definition, wording, discovery, use-case context, specification, validation, and initial class analysis without prescribing implementation.
- Examples
- Uses a book catalogue with librarian maintenance, customer search, typed attributes, case-insensitive matching, and don’t-care fields.
- What you can do after
- Evaluate intended behavior, write verifiable requirements, structure use cases, and derive an initial set of application classes.
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Object-Oriented Software Design in C++
A documented requirement specifying an operation an application must perform or allow an end user to perform.
- How it is used
- Defines the observable operations needed to turn client goals into an application that performs the right behavior.
- How deep it goes
- Defines operations, wording, quality criteria, use-case context, and specification contents, but stops short of internal implementation details.
- Examples
- Uses a book catalogue with book types, attributes, case-insensitive searches, wildcard values, customer searches, and librarian maintenance.
- What you can do after
- Evaluate/understand requirements by writing verifiable must-or-shall statements, relating them to use cases, and checking black-box outcomes.
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Kafka for Architects
A functional requirement specifies a capability or behavior that a system must provide.
- How it is used
- Guides Kafka-fit validation and converts business event needs into governed topic and client requirements.
- How deep it goes
- Enumerates topic-level fields and design decisions, but leaves infrastructure sizing and tuning to nonfunctional requirements.
- Examples
- Uses approval workflows, risk and compliance checks, shared identifiers, event schemas, consumer groups, and topic definitions.
- What you can do after
- Apply it via AsyncAPI or organizational data-definition systems to document topics, clients, schemas, and consumption behavior.
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Functional Design and Architecture: Examples in Haskell
A functional requirement specifies functionality that an application must provide for users to complete tasks.
- How it is used
- Guides software design by stating the functionality users need to complete their tasks.
- How deep it goes
- Defines functional requirements and contrasts them with nonfunctional requirements, without detailing implementation techniques.
- Examples
- Uses manual and automatic spacecraft control as the central functional example.
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Machine Learning System Design
A requirement that specifies the functionality, value, or user flow a system or feature must provide.
- How it is used
- Frames the functionality, value, and user flow that an ML feature or system should provide.
- How deep it goes
- Defines the concept and contrasts it with nonfunctional requirements, without prescribing a detailed elicitation process.
- Examples
- Uses a dynamic pricing system involving revenue, margin, traffic, user-level operation, adaptation, and real-time pricing.
- What you can do after
- Apply it to determine what a feature or system should provide before shaping implementation constraints.
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Related concepts
- nonfunctional requirementcontrasts with · A nonfunctional requirement specifies a quality attribute, constraint, or operating condition that a system must satisfy beyond the particular functions it performs.
- requirementskind of · A requirement is a stated need, capability, quality, condition, or constraint that a system, product, solution, or project is expected to satisfy.
- white-box testingmeasured by · White-box testing is a software testing technique that evaluates behavior using knowledge of the software’s internal implementation, structure, or execution paths.
- requirements analysisused by · Requirements analysis is the systematic process of eliciting, clarifying, assessing, and documenting the needs and constraints a system or product must satisfy.
- use caseused by · A use case is a description of a situation or interaction in which a system, method, or capability is applied to achieve or support a goal or outcome.
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