Run Worker processes - .NET SDK

Run Worker Process

How to create and run a Worker Process using the Temporal .NET SDK

The Worker Process is where Workflow Functions and Activity Functions are executed.

• Each Worker Entity in the Worker Process must register the exact Workflow Types and Activity Types it may execute.
• Each Worker Entity must also associate itself with exactly one Task Queue.
• Each Worker Entity polling the same Task Queue must be registered with the same Workflow Types and Activity Types.

A Worker Entity is the component within a Worker Process that listens to a specific Task Queue.

Although multiple Worker Entities can be in a single Worker Process, a single Worker Entity Worker Process may be perfectly sufficient. For more information, see the Worker tuning guide.

A Worker Entity contains a Workflow Worker and/or an Activity Worker, which makes progress on Workflow Executions and Activity Executions, respectively.

To develop a Worker, create a new Temporalio.Worker.TemporalWorker providing the Client and worker options which include Task Queue, Workflows, and Activities and more. The following code example creates a Worker that polls for tasks from the Task Queue and executes the Workflow. When a Worker is created, it accepts a list of Workflows, a list of Activities, or both.

// Create a client to localhost on default namespace
var client = await TemporalClient.ConnectAsync(new("localhost:7233")
{
    LoggerFactory = LoggerFactory.Create(builder =>
        builder.
            AddSimpleConsole(options => options.TimestampFormat = "[HH:mm:ss] ").
            SetMinimumLevel(LogLevel.Information)),
});

// Cancellation token cancelled on ctrl+c
using var tokenSource = new CancellationTokenSource();
Console.CancelKeyPress += (_, eventArgs) =>
{
    tokenSource.Cancel();
    eventArgs.Cancel = true;
};

// Create an activity instance with some state
var activities = new MyActivities();

// Run worker until cancelled
Console.WriteLine("Running worker");
using var worker = new TemporalWorker(
    client,
    new TemporalWorkerOptions(taskQueue: "my-task-queue").
        AddAllActivities(activities).
        AddWorkflow<MyWorkflow>());
try
{
    await worker.ExecuteAsync(tokenSource.Token);
}
catch (OperationCanceledException)
{
    Console.WriteLine("Worker cancelled");
}

All Workers listening to the same Task Queue name must be registered to handle the exact same Workflows Types and Activity Types.

If a Worker polls a Task for a Workflow Type or Activity Type it does not know about, it fails that Task. However, the failure of the Task does not cause the associated Workflow Execution to fail.

Worker Processes with host builder and dependency injection

The Temporalio.Extensions.Hosting extension exists for .NET developers to support HostBuilder and Dependency Injection approaches.

To create the same worker as before using this approach:

var host = Host.CreateDefaultBuilder(args)
    .ConfigureLogging(ctx => ctx.AddSimpleConsole().SetMinimumLevel(LogLevel.Information))
    .ConfigureServices(ctx =>
        ctx.
            // Add the database client at the scoped level
            AddScoped<IMyDatabaseClient, MyDatabaseClient>().
            // Add the worker
            AddHostedTemporalWorker(
                clientTargetHost: "localhost:7233",
                clientNamespace: "default",
                taskQueue: "my-task-queue").
            // Add the activities class at the scoped level
            AddScopedActivities<MyActivities>().
            AddWorkflow<MyWorkflow>())
    .Build();
await host.RunAsync();