# Wait for a file, table or signal Control / flow A variant of [Branch or loop](https://meridian.online/operations/branch-or-loop). Hold the run until a file, table, query result or release signal appears, or a time-out passes. Page: ## Status Not built yet. arcform does not do this yet; it would live in how a Protocol runs. [Its place on the roadmap](https://meridian.online/roadmap#branch-or-loop) ## What other tools call it Meridian's classification; an independent blind rating agreed on 95.7% of 324 rows (variant, version 3). - Azure Data Factory: [`Validation Activity`](https://learn.microsoft.com/en-us/azure/data-factory/control-flow-validation-activity) (read 2026-09-27) - Bruin: [`Query sensors (family)`](https://getbruin.com/docs/bruin/assets/sensor.html) (read 2026-09-27) - Bruin: [`Table sensors (family)`](https://getbruin.com/docs/bruin/assets/sensor.html) (read 2026-09-27) - Bruin: [`gcs.sensor.object`](https://getbruin.com/docs/bruin/platforms/gcs.html) (read 2026-09-27) - Bruin: [`gcs.sensor.prefix`](https://getbruin.com/docs/bruin/platforms/gcs.html) (read 2026-09-27) - Bruin: [`s3.sensor.key_sensor`](https://getbruin.com/docs/bruin/platforms/s3.html) (read 2026-09-27) - Apache Hop: [`Wait for SQL`](https://hop.apache.org/manual/latest/workflow/actions/waitforsql.html) (read 2026-09-27) - Apache Hop: [`Wait for file`](https://hop.apache.org/manual/latest/workflow/actions/waitforfile.html) (read 2026-09-27) - Apache NiFi: [`Notify`](https://nifi.apache.org/components/org.apache.nifi.processors.standard.Notify/) (read 2026-09-27) - Apache NiFi: [`Wait`](https://nifi.apache.org/components/org.apache.nifi.processors.standard.Wait/) (read 2026-09-27) - SQLMesh: [`Signals`](https://github.com/SQLMesh/sqlmesh/blob/23b237cea7218cc8f338b89c14f0957394a0003b/docs/guides/signals.md) (read 2026-09-27) - Talend: [`tWaitForFile`](https://help.qlik.com/talend/en-US/components/8.0/orchestration/orchestration-component) (read 2026-09-27) - Talend: [`tWaitForSocket`](https://help.qlik.com/talend/en-US/components/8.0/orchestration/orchestration-component) (read 2026-09-27) - Talend: [`tWaitForSqlData`](https://help.qlik.com/talend/en-US/components/8.0/orchestration/orchestration-component) (read 2026-09-27)