# Self-Hosting in Azure WebJobs


This is an example of how an NServiceBus endpoint can be hosted using Azure WebJobs. This sample is compatible with Azure WebJobs SDK 3.0.

## Running in development mode

 1. Start the [Azurite Storage Emulator](https://learn.microsoft.com/en-us/azure/storage/common/storage-use-azurite).
 2. Run the solution.

## Code walk-through

This sample contains one project:

- Receiver: A self-hosted endpoint running in a continuous WebJob.

### Receiver

The receiver uses the self-hosting capability to start an endpoint inside a WebJob.

The `UseNServiceBus` method of [`NServiceBus.Extensions.Hosting`](/nservicebus/hosting/extensions-hosting.md) is used to configure and start the endpoint:

<!-- snippet: WebJobHost_Start -->

```cs
hostBuilder.ConfigureServices((hostBuilderContext, services) =>
{
    var endpointConfiguration = new EndpointConfiguration("receiver");
    endpointConfiguration.DefineCriticalErrorAction(OnCriticalError);
    endpointConfiguration.UsePersistence<NonDurablePersistence>();
    endpointConfiguration.UseSerialization<SystemJsonSerializer>();
    endpointConfiguration.EnableInstallers();

    var transportConnectionString = hostBuilderContext.Configuration.GetConnectionString("TransportConnectionString");
    endpointConfiguration.UseTransport(new AzureStorageQueueTransport(transportConnectionString));

    services.AddNServiceBusEndpoint(endpointConfiguration);
});
```

<!-- endsnippet -->

> [!NOTE]
> If dependencies need to be shared between the service collection and NServiceBus infrastructure (e.g., message handlers), refer to the [ASP.NET Core sample](/samples/dependency-injection/aspnetcore/index.md).

A [critical error](/nservicebus/hosting/critical-errors.md) action must be defined to restart the host when a critical error occurs:

<!-- snippet: WebJobHost_CriticalError -->

```cs
static async Task OnCriticalError(ICriticalErrorContext context, CancellationToken cancellationToken)
{
    var fatalMessage =
        $"The following critical error was encountered:{Environment.NewLine}{context.Error}{Environment.NewLine}Process is shutting down. StackTrace: {Environment.NewLine}{context.Exception.StackTrace}";

    try
    {
        await context.Stop(cancellationToken);
    }
    finally
    {
        Environment.FailFast(fatalMessage, context.Exception);
    }
}
```

<!-- endsnippet -->

When the WebJob host stops, the endpoint is automatically stopped with it by the hosting extension.