Do context propagation for a running workflow

Community Support
1

We are using a Temporal self-hosted server. The key versions:

  1. Temporal server 1.22.3
  2. Postgres Database version 14.11
  3. The application is using the Java SDK.

We are using a ContextPropagator implementation to send tracing information from our client to the worker. This works without any problems.

Our workflow can create a child workflow in certain cases. The child workflow creation uses setContextPropagator as follow.

ChildWorkflowOptions options = ChildWorkflowOptions.newBuilder()
                  .setParentClosePolicy(ParentClosePolicy.PARENT_CLOSE_POLICY_ABANDON)
                    .setContextPropagators(Collections.singletonList(new MdcContextPropagator()))
                    .setTaskQueue("taskqueue")
                    .build();

Again this works fine and we see the context inside the child workflow.

The child workflow includes a signal method to wake up the workflow, check the result from a downstream API. Depending on the result it will either go back to sleep or complete.

This is the interface for the child workflow

@WorkflowInterface
public interface ChildProcessingWorkflow {

    @WorkflowMethod
    void startProcessing();

    @SignalMethod
    void resumeProcessing();
}

At the moment we call it asynchronously using:

ChildProcessingWorkflow workflow = workflowClient.newWorkflowStub(ChildProcessingWorkflow.class, options);
 CompletableFuture.supplyAsync(() -> WorkflowClient.execute(workflow::startProcessing)
.thenRunAsync(workflow::resumeProcessing);

I can see the context serialisation occur in the client but it’s not updated in the child workflow. My question is whether it’s possible to do context propagation for a workflow that is already running?

2

What do you mean by “context propagation for already running workflow”? Do you want the context from the signal sender to be available inside the signal handler?

3

Yes. Can the signal sender send an updated context to the workflow?

4

@maxim My question here was whether the signal sender can update the context to the workflow. Is this doable?

5

It might be possible by implementing a custom workflow interceptor.

6

You might be able to achieve this by implementing a custom workflow interceptor to handle the different user preferences and ensure separation between profiles.