Skip to main content

Child Workflows - .NET SDK

This page shows how to do the following:

Start a Child Workflow Execution​

A Child Workflow Execution is a Workflow Execution that is scheduled from within another Workflow using a Child Workflow API.

When using a Child Workflow API, Child Workflow related Events (StartChildWorkflowExecutionInitiated, ChildWorkflowExecutionStarted, ChildWorkflowExecutionCompleted, etc...) are logged in the Workflow Execution Event History.

The ChildWorkflowExecutionStarted Event must be logged to the Event History before the Parent Workflow completes to ensure the Child Workflow has started. In .NET, awaiting StartChildWorkflowAsync() or ExecuteChildWorkflowAsync() internally waits for this Event before returning, so the Child Workflow is guaranteed to have started once the call resolves. If you start a Child Workflow from a non-main context (for example, a Signal or Update handler), make sure the Parent Workflow doesn't complete before that call resolves.

To spawn a Child Workflow Execution in .NET, use the ExecuteChildWorkflowAsync() method which starts the Child Workflow and waits for completion or use the StartChildWorkflowAsync() method to start a Child Workflow and return its handle. This is useful if you want to do something after it has only started, or to get the Workflow/Run ID, or to be able to signal it while running.

note

ExecuteChildWorkflowAsync() is a helper method for StartChildWorkflowAsync() plus await handle.GetResultAsync().

await Workflow.ExecuteChildWorkflowAsync((MyChildWorkflow wf) => wf.RunAsync());

Set a Parent Close Policy​

A Parent Close Policy determines what happens to a Child Workflow Execution if its Parent changes to a Closed status (Completed, Failed, or Timed Out).

The default Parent Close Policy option is set to terminate the Child Workflow Execution.

Set the ParentClosePolicy property inside the ChildWorkflowOptions for ExecuteChildWorkflowAsync or StartChildWorkflowAsync to specify the behavior of the Child Workflow when the Parent Workflow closes.

await Workflow.ExecuteChildWorkflowAsync(
  (MyChildWorkflow wf) => wf.RunAsync(),
  new() { ParentClosePolicy = ParentClosePolicy.Abandon });