signals-queries-updates

Signals allow external systems to send event-driven inputs to running Temporal workflows by defining signal handlers that react to external events and process them during execution without stopping the workflow.

You can query the live state of a Temporal workflow without mutating data by defining query handlers that expose current workflow progress and internal state safely to external callers.

The best way to apply validated updates to a running Temporal workflow is using update patterns, which allow you to apply state mutations and observe the results safely after validation passes.

Temporal signals, queries, and updates combine for approval flows by using signals to receive requests, queries to inspect current status, and updates to apply validated state mutations and return observed results.

You need signals and queries in long-running Temporal workflows when external systems must drive event-driven actions or read live workflow progress without interrupting or mutating the running state.