Deadline
The time bound by which a real-time task or operation must complete for its result to remain valid or useful.
A deadline defines not only how long work takes but the latest time at which completion remains acceptable. For periodic real-time tasks, the window between release time and deadline constrains scheduling and WCET analysis. In a distributed request, an end-to-end deadline may be divided across network, queueing, and downstream-service stages.
A deadline is not the same as a timeout. A timeout is usually an operational mechanism that stops waiting; a deadline expresses the timing requirement of the work. If timeout values are chosen independently, a request may continue to consume resources after its result has already become useless.
Related: Real-Time System, Worst-Case Execution Time, Jitter, Deadline Propagation.