How to develop a Worker program in TypeScript

Create a Worker with Worker.create() (which establishes the initial gRPC connection), then call worker.run() on it (to start polling the Task Queue).

Below is an example of starting a Worker that polls the Task Queue named tutorial.

TypeScript

import { Worker } from '@temporalio/worker';
import * as activities from './activities';

async function run() {
  // Step 1: Register Workflows and Activities with the Worker and connect to
  // the Temporal server.
  const worker = await Worker.create({
    workflowsPath: require.resolve('./workflows'),
    activities,
    taskQueue: 'hello-world',
  });
  // Worker connects to localhost by default and uses console.error for logging.
  // Customize the Worker by passing more options to create():
  // https://typescript.temporal.io/api/classes/worker.Worker
  // If you need to configure server connection parameters, see docs:
  // https://docs.temporal.io/typescript/security#encryption-in-transit-with-mtls

  // Step 2: Start accepting tasks on the `hello-world` queue
  await worker.run();
}

run().catch((err) => {
  console.error(err);
  process.exit(1);
});

JavaScript

import { Worker } from '@temporalio/worker';
import * as activities from './activities';

async function run() {
  // Step 1: Register Workflows and Activities with the Worker and connect to
  // the Temporal server.
  const worker = await Worker.create({
    workflowsPath: require.resolve('./workflows'),
    activities,
    taskQueue: 'hello-world',
  });
  // Worker connects to localhost by default and uses console.error for logging.
  // Customize the Worker by passing more options to create():
  // https://typescript.temporal.io/api/classes/worker.Worker
  // If you need to configure server connection parameters, see docs:
  // https://docs.temporal.io/typescript/security#encryption-in-transit-with-mtls
  
  // Step 2: Start accepting tasks on the `hello-world` queue
  await worker.run();
}

run().catch((err) => {
  console.error(err);
  process.exit(1);
});

taskQueue is the only required option, but you will also use workflowsPath and activities to register Workflows and Activities with the Worker.

A full example for Workers looks like this:

import { Worker, NativeConnection } from '@temporalio/worker';
import * as activities from './activities';

async function run() {
  const connection = await NativeConnection.connect({
    // defaults port to 7233 if not specified
    address: 'foo.bar.tmprl.cloud',
    tls: {
      // set to true if TLS without mTLS
      // See docs for other TLS options
      clientCertPair: {
        crt: clientCert,
        key: clientKey,
      },
    },
  });

  const worker = await Worker.create({
    connection,
    namespace: 'foo.bar', // as explained in Namespaces section
    // ...
  });
  await worker.run();
}

run().catch((err) => {
  console.error(err);
  process.exit(1);
});

See below for more Worker options.

Workflow and Activity registration

Workers bundle Workflow code and node_modules using Webpack v5 and execute them inside V8 isolates. Activities are directly required and run by Workers in the Node.js environment.

Workers are very flexible – you can host any or all of your Workflows and Activities on a Worker, and you can host multiple Workers in a single machine.

There are three main things the Worker needs:

• taskQueue: the Task Queue to poll. This is the only required argument.
• activities: Optional. Imported and supplied directly to the Worker. Not the path.
• Workflow bundle:
• Either specify a workflowsPath to your workflows.ts file to pass to Webpack, e.g., require.resolve('./workflows'). Workflows will be bundled with their dependencies.
• Or pass a prebuilt bundle to workflowBundle instead if you prefer to handle the bundling yourself.

Additional Worker Options

This is a selected subset of options you are likely to use. Even more advanced options, particularly for performance tuning, are available in the API reference.

Options	Description
dataConverter	Encodes and decodes data entering and exiting a Temporal Server. Supports undefined, UintBArray, and JSON.
sinks	Allows injection of Workflow Sinks (Advanced feature: see Logging docs)
interceptors	A mapping of interceptor type to a list of factories or module paths (Advanced feature: see Interceptors)

Operation guides:

• How to tune Workers