CloseNotification

CloseNotification is a type of inter-component message used in software systems to signal the intent to end or release a resource, window, or process. It is part of event-driven and messaging architectures that aim to decouple the initiator of a close action from the component that performs the actual shutdown or cleanup. CloseNotification typically flows from a producer or controller to a consumer or managed object, requesting that it begin the closing sequence.

A CloseNotification commonly carries metadata such as the origin of the message (source), the intended recipient (target), a reason for closing, and a timestamp. Many implementations include a cancellable or negotiable aspect, allowing the receiver to confirm or veto the close depending on current state or constraints. Reasons are often enumerated and may include user request, system shutdown, error condition, timeout, or cancellation.

Processing a CloseNotification usually involves initiating cleanup, saving state if appropriate, and determining whether the close can proceed. If the receiver can safely close, it completes the shutdown sequence and may emit a subsequent acknowledgement or finalization signal. In some frameworks, a separate event or message (such as a CloseAcknowledgement or CloseEvent) accompanies or follows the initial notification to confirm completion.

Variations exist across platforms; some systems prefer a CloseEvent rather than a CloseNotification. Related concepts include OpenNotification, CancelNotification, and EndSession signals.