Skip to content

Latest commit

 

History

History
102 lines (72 loc) · 4.81 KB

scoped-service.md

File metadata and controls

102 lines (72 loc) · 4.81 KB
Raw
title description author ms.author ms.date ms.topic
Use scoped services within a BackgroundService
Learn how to use scoped services within a BackgroundService in .NET.
IEvangelist
dapine
12/13/2023
tutorial

Use scoped services within a BackgroundService

When you register implementations of xref:Microsoft.Extensions.Hosting.IHostedService using any of the xref:Microsoft.Extensions.DependencyInjection.ServiceCollectionHostedServiceExtensions.AddHostedService%2A extension methods - the service is registered as a singleton. There may be scenarios where you'd like to rely on a scoped service. For more information, see Dependency injection in .NET: Service lifetimes.

In this tutorial, you learn how to:

[!div class="checklist"]

  • Resolve scoped dependencies in a singleton xref:Microsoft.Extensions.Hosting.BackgroundService.
  • Delegate work to a scoped service.
  • Implement an override of xref:Microsoft.Extensions.Hosting.BackgroundService.StopAsync(System.Threading.CancellationToken)?displayProperty=nameWithType.

[!INCLUDE workers-samples-browser]

Prerequisites

[!INCLUDE file-new-worker]

Create scoped services

To use scoped services within a BackgroundService, create a scope. No scope is created for a hosted service by default. The scoped background service contains the background task's logic.

:::code source="snippets/workers/scoped-service/IScopedProcessingService.cs":::

The preceding interface defines a single DoWorkAsync method. To define the default implementation:

  • The service is asynchronous. The DoWorkAsync method returns a Task. For demonstration purposes, a delay of ten seconds is awaited in the DoWorkAsync method.
  • An xref:Microsoft.Extensions.Logging.ILogger is injected into the service.:

:::code source="snippets/workers/scoped-service/DefaultScopedProcessingService.cs":::

The hosted service creates a scope to resolve the scoped background service to call its DoWorkAsync method. DoWorkAsync returns a Task, which is awaited in ExecuteAsync:

Rewrite the Worker class

Replace the existing Worker class with the following C# code, and rename the file to ScopedBackgroundService.cs:

:::code source="snippets/workers/scoped-service/ScopedBackgroundService.cs" highlight="22-28":::

In the preceding code, an explicit scope is created and the IScopedProcessingService implementation is resolved from the dependency injection service scope factory. The resolved service instance is scoped, and its DoWorkAsync method is awaited.

Replace the template Program.cs file contents with the following C# code:

:::code source="snippets/workers/scoped-service/Program.cs" highlight="4-5":::

The services are registered in (Program.cs). The hosted service is registered with the AddHostedService extension method.

For more information on registering services, see Dependency injection in .NET.

Verify service functionality

[!INCLUDE run-app]

Let the application run for a bit to generate several execution count increments. You will see output similar to the following:

info: App.ScopedService.ScopedBackgroundService[0]
      ScopedBackgroundService is running.
info: App.ScopedService.ScopedBackgroundService[0]
      ScopedBackgroundService is working.
info: App.ScopedService.DefaultScopedProcessingService[0]
      DefaultScopedProcessingService working, execution count: 1
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: .\scoped-service
info: App.ScopedService.DefaultScopedProcessingService[0]
      DefaultScopedProcessingService working, execution count: 2
info: App.ScopedService.DefaultScopedProcessingService[0]
      DefaultScopedProcessingService working, execution count: 3
info: App.ScopedService.DefaultScopedProcessingService[0]
      DefaultScopedProcessingService working, execution count: 4
info: Microsoft.Hosting.Lifetime[0]
      Application is shutting down...
info: App.ScopedService.ScopedBackgroundService[0]
      ScopedBackgroundService is stopping.

[!INCLUDE stop-app]

See also