Temporal Signals#

Workflows often need input after they have started. A deployment workflow pauses for human approval. An expense workflow waits for a manager’s signature. An incident response workflow escalates after a timeout. Temporal signals are the mechanism for delivering external input to a running workflow.

A signal is a message sent to a workflow from outside – from another workflow, from a CLI command, from an HTTP endpoint, or from any system that has the Temporal client. The workflow receives the signal, processes it, and continues execution. Signals are durable: if the worker crashes after a signal is sent but before the workflow processes it, the signal is replayed when the worker restarts.