NexusCancellation

Nexus Cancellation

This sample demonstrates how to cancel a Nexus operation from a caller workflow. It uses a CancellationType of WaitCancellationRequested, which allows the caller workflow to return after the handler workflow has received the cancellation.

Instructions

To run, first see README.md for prerequisites such as starting the Temporal server.

Run the following to create both namespaces and an endpoint:

temporal operator namespace create --namespace nexus-cancellation-handler-namespace
temporal operator namespace create --namespace nexus-cancellation-caller-namespace

temporal operator nexus endpoint create \
  --name nexus-cancellation-endpoint \
  --target-namespace nexus-cancellation-handler-namespace \
  --target-task-queue nexus-cancellation-handler-sample

In one terminal, run the handler worker from this directory:

dotnet run handler-worker

In a second terminal, run the caller worker from this directory:

dotnet run caller-worker

In a third terminal, run the caller workflow from this directory:

dotnet run caller-workflow

Output

Caller Worker Output

The caller worker output shows when the first operation completes followed by the cancellation of the other operations.

[23:21:04] info: Program[0]
      Running caller worker
[23:21:11] info: Temporalio.Workflow:HelloCallerWorkflow[0]
      First operation completed, cancelling remaining operations
[23:21:11] info: Temporalio.Workflow:HelloCallerWorkflow[0]
      Operation was cancelled
[23:21:11] info: Temporalio.Workflow:HelloCallerWorkflow[0]
      Operation was cancelled
[23:21:11] info: Temporalio.Workflow:HelloCallerWorkflow[0]
      Operation was cancelled

Handler Worker Output

The handler worker output shows which operations were canceled.

[23:20:59] info: Program[0]
      Running handler worker
[23:21:10] info: Temporalio.Workflow:HelloHandlerWorkflow[0]
      HelloHandlerWorkflow started for Temporal in Es
[23:21:10] info: Temporalio.Workflow:HelloHandlerWorkflow[0]
      HelloHandlerWorkflow started for Temporal in En
[23:21:10] info: Temporalio.Workflow:HelloHandlerWorkflow[0]
      HelloHandlerWorkflow started for Temporal in Fr
[23:21:10] info: Temporalio.Workflow:HelloHandlerWorkflow[0]
      HelloHandlerWorkflow started for Temporal in Tr
[23:21:10] info: Temporalio.Workflow:HelloHandlerWorkflow[0]
      HelloHandlerWorkflow started for Temporal in De
[23:21:14] info: Temporalio.Workflow:HelloHandlerWorkflow[0]
      HelloHandlerWorkflow for Temporal in Fr was cancelled after 00:00:04 of work, performed 00:00:03 of cleanup
[23:21:14] info: Temporalio.Workflow:HelloHandlerWorkflow[0]
      HelloHandlerWorkflow for Temporal in En was cancelled after 00:00:04 of work, performed 00:00:03 of cleanup
[23:21:14] info: Temporalio.Workflow:HelloHandlerWorkflow[0]
      HelloHandlerWorkflow for Temporal in Es was cancelled after 00:00:04 of work, performed 00:00:03 of cleanup

Workflow Result

The caller workflow output shows the result of the first completed operation.

[23:21:09] info: Program[0]
      Executing caller hello workflow
[23:21:11] info: Program[0]
      Workflow result: Hallo Temporal 👋

Note on Timing

As this sample uses the CancellationType of WaitCancellationRequested you can see that the caller workflow result logs before the cleanup work finishes on the cancelled operations. In the timing above, the caller workflow result logs at 23:21:11, the cancellations are also logged at 23:21:11 and the handler workflows complete their 3 seconds of cleanup work and log at 23:21:14.