Sending signal to Scheduled workflow - how to obtain or set WorkflowID?

Community Support
1

Hi -

We’re using Schedules, and need to using/sending Signal to Scheduled Workflow.
We know how to send signal:

temporalClient.SignalWorkflow(ctx, myWorkflowID, "", BLAH)

However, to the best of my knowledge, there is no way to set Scheduled WorkflowID - it’s always auto-generated with a prefix (ScheduleID or WorkflowName), plus a timestampe, eg: my_schedule_id-2024-10-31T03:35:00Z.

  • this is a problem for sending signal, which requires (deterministic, or known) WorkflowID.

Is it possible to send signal to scheduled workflow?

2

Based on your overlap policy (What is a Temporal Workflow? | Temporal Platform Documentation), you could have multiple workflows running at the same time from the same schedule if the workflow might run for longer than the schedule interval. So, you need some way of deciding which workflow execution you want to send the signal to.

If you might perhaps want to send the signal to the most recent execution, one option might be to have a long running coordination workflow. When the scheduled workflow starts, it could signal the coordination workflow its workflow id. When you wanted to signal the scheduled workflow, you could signal the coordination workflow, which knowing the scheduled workflow’s workflow id could then signal the scheduled workflow.

3

Thanks - this seems to be a good idea that should work.