Requirementswhile

Requirementswhile is a term used in software engineering and requirements engineering to denote a construct that expresses that a specified set of requirements must be maintained while a controlling condition remains true. It functions similarly to a while-loop in programming, but applies to the state of a system's requirements rather than to a sequence of instructions. In practice, requirementswhile allows engineers to specify that, during the active phase of a process or operation, certain constraints, invariants, or performance criteria must continuously hold.

Notation and use can vary by context. Informal variants include constructs such as while (condition) { R1; R2; R3; } or a declarative form like requirementswhile (condition) ensures R1, R2, R3. In formal methods, this idea is often represented with temporal logic or runtime monitoring that requires the listed properties to hold globally while the controlling condition remains true. The concept emphasizes ongoing compliance rather than a one-time verification.

Examples help illustrate the idea. For instance, while the battery is charging, the charging current must remain within safe limits and the temperature must stay below a defined threshold. In a medical device, while therapy is active, delivered power and safety constraints must be continuously satisfied.

Origin and status: the term emerged in practitioner and academic discussions in the 2020s and is not tied to a single standard language or methodology. Its precise interpretation can vary, so practitioners typically specify exact semantics within their project’s notation and tooling.

Related concepts include invariants, preconditions and postconditions, temporal logic, and runtime monitoring. Limitations include potential ambiguity without formalization and the need for tool support to verify ongoing compliance.

See also: requirement engineering, temporal logic, invariants, runtime monitoring.