Update-with-start

[dandavison]

This PR adds an API for "update-with-start", using the MultiOperation gRPC API.

The test suite is incomplete, but please feel free to review the API, implementation, and tests that are present.

The following code demonstrates the API and is taken from the early-return sample:

  const startWorkflowOperation = WithStartWorkflowOperation.create(transactionWorkflow, {
    workflowId,
    args: [transactionID],
    taskQueue: 'early-return',
    workflowIdConflictPolicy: 'FAIL',
  });

  const earlyConfirmation = await client.workflow.executeUpdateWithStart(getTransactionConfirmation, {
    startWorkflowOperation,
  });
  const wfHandle = await startWorkflowOperation.workflowHandle();
  const finalReport = await wfHandle.result();

Public API

• New client interceptor startUpdateWithStart with interfaces WorkflowStartUpdateWithStartInput and WorkflowStartUpdateWithStartOutput
• New class WithStartWorkflowOperation
• WorkflowClient.executeUpdateWithStart and WorkflowClient.startUpdateWithStart

[mjameswh]

Put that error in client/src/errors.ts instead.

[mjameswh]

Also, not a fan of the name. "custom" in this context means nothing to the end user. Could we have more targetted errors? Or merge this one with client.ServiceError?

[dandavison]

Reverted all changes to common/src. Still not sure how to rethrow GrpcServiceError. One option seems to be just to mutate the received error and re-throw it.

[dandavison]

I am:

• Identifying WorkflowExecutionAlreadyStartedError and using that as the error if appropriate
• Otherwise mutating the received error so that it acquires the more specific GrpcServiceError fields (code, message) as unpacked from the MultiOp error, and rethrowing the altered GrpcServiceError error

[mjameswh]

What kind of details do we have here? Could we map these statuses to error classes that we already have elsewhere?

[dandavison]

See above #1585 (comment)

[mjameswh]

Please make sure to add @experimental annotations on all publicly exposed APIs introduced in this PR.

[mjameswh]

Can live with this temporarily, but we should avoid ad-hoc types in public facing APIs.

[dandavison]

This is ready for another pass @mjameswh

[dandavison]

One uncertainty I have is exactly how we should construct the WithStartWorkflowOperation, i.e. whether via new or via a factory function.

[mjameswh]

Awesome!

[dandavison]

Thanks very much for the expert reviewing @mjameswh, as always.