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Asynchronous Activity Completion

How to asynchronously complete an Activity​

Asynchronous Activity Completion enables the Activity Function to return without the Activity Execution completing.

There are three steps to follow:

  1. The Activity provides the external system with identifying information needed to complete the Activity Execution. Identifying information can be a Task Token, or a combination of Namespace, Workflow Id, and Activity Id.
  2. The Activity Function completes in a way that identifies it as waiting to be completed by an external system.
  3. The Temporal Client is used to Heartbeat and complete the Activity.

To asynchronously complete an Activity, call AsyncCompletionClient.complete.

activities-examples/src/activities/async-completion.ts

import { activityInfo, CompleteAsyncError } from '@temporalio/activity';
import { AsyncCompletionClient } from '@temporalio/client';

export async function doSomethingAsync(): Promise<string> {
  const taskToken = activityInfo().taskToken;
  setTimeout(() => doSomeWork(taskToken), 1000);
  throw new CompleteAsyncError();
}

// this work could be done in a different process or on a different machine
async function doSomeWork(taskToken: Uint8Array): Promise<void> {
  const client = new AsyncCompletionClient();
  // does some work...
  await client.complete(taskToken, 'Job\'s done!');
}

Local Activities​

To call Local Activities in TypeScript, use proxyLocalActivities.

import * as workflow from '@temporalio/workflow';

const { getEnvVar } = workflow.proxyLocalActivities({
  startToCloseTimeout: '2 seconds',
});

export async function yourWorkflow(): Promise<void> {
  const someSetting = await getEnvVar('SOME_SETTING');
  // ...
}

Local Activities must be registered with the Worker the same way non-local Activities are.