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.NET Aspire Azure Web PubSub component

  • Article

In this article, you learn how to use the .NET Aspire Azure Web PubSub component. The Aspire.Azure.Messaging.WebPubSub library offers options for registering an WebPubSubServiceClient in the DI container for connecting to Azure Web PubSub.

Prerequisites

  • Azure subscription: create one for free.
  • An existing Azure Web PubSub service instance. For more information, see Create a Web PubSub resource. Alternatively, you can use a connection string, which isn't recommended in production environments.

Get started

To get started with the .NET Aspire Azure Web PubSub component, install the Aspire.Azure.Messaging.WebPubSub NuGet package in the consuming client project.

dotnet add package Aspire.Azure.Messaging.WebPubSub

For more information, see dotnet add package or Manage package dependencies in .NET applications.

Example usage

In the Program.cs file of your project, call the AddAzureWebPubSubHub extension method to register a WebPubSubServiceClient for use via the dependency injection container. The method takes a connection name parameter.

builder.AddAzureWebPubSubServiceClient("wps");

You can then retrieve the WebPubSubServiceClient instance using dependency injection. For example, to retrieve the client from a service:

public class ExampleService(WebPubSubServiceClient client)
{
    // Use client...
}

For more information, see the Azure.Messaging.WebPubSub documentation.

App host usage

To add Azure Web PubSub hosting support to your IDistributedApplicationBuilder, install the Aspire.Hosting.Azure.WebPubSub NuGet package in the app host project.

dotnet add package Aspire.Hosting.Azure.WebPubSub

In your app host project, add a Web PubSub connection and consume the connection using the following methods:

var webPubSub = builder.AddAzureWebPubSub("wps");

var exampleService = builder.AddProject<Projects.ExampleService>()
                            .WithReference(webPubSub);

The AddAzureWebPubSubHub method reads connection information from the app host's configuration (for example, from "user secrets") under the ConnectionStrings:wps configuration key. The WithReference method passes that connection information into a connection string named wps in the ExampleService project. In the Program.cs file of ExampleService, the connection can be consumed using:

builder.AddAzureWebPubSubServiceClient("wps");

Configuration

The .NET Aspire Azure Web PubSub library provides multiple options to configure the Azure Web PubSub connection based on the requirements and conventions of your project. Note that either a Endpoint or a ConnectionString is a required to be supplied.

Use a connection string

When using a connection string from the ConnectionStrings configuration section, you can provide the name of the connection string when calling builder.AddAzureWebPubSubHub():

builder.AddAzureWebPubSubServiceClient(
    "WebPubSubConnectionName",
    "your_hub_name");

And then the connection information will be retrieved from the ConnectionStrings configuration section. Two connection formats are supported:

Use the service endpoint

The recommended approach is to use the service endpoint, which works with the AzureMessagingWebPubSubSettings.Credential property to establish a connection. If no credential is configured, the DefaultAzureCredential is used.

{
  "ConnectionStrings": {
    "WebPubSubConnectionName": "https://xxx.webpubsub.azure.com"
  }
}

Connection string

Alternatively, a connection string can be used.

{
  "ConnectionStrings": {
    "WebPubSubConnectionName": "Endpoint=https://xxx.webpubsub.azure.com;AccessKey==xxxxxxx"
  }
}

Use configuration providers

The .NET Aspire Azure Web PubSub library supports Microsoft.Extensions.Configuration. It loads the AzureMessagingWebPubSubSettings and WebPubSubServiceClientOptions from configuration by using the Aspire:Azure:Messaging:WebPubSub key. Consider the example appsettings.json that configures some of the options:

{
  "Aspire": {
    "Azure": {
      "Messaging": {
        "WebPubSub": {
          "DisableHealthChecks": true,
          "HubName": "your_hub_name"
        }
      }
    }
  }
}

Use inline delegates

You can also pass the Action<AzureMessagingWebPubSubSettings> configureSettings delegate to set up some or all the options inline, for example to disable health checks from code:

builder.AddAzureWebPubSubServiceClient(
    "wps",
    settings => settings.DisableHealthChecks = true);

You can also setup the WebPubSubServiceClientOptions using the optional Action<IAzureClientBuilder<WebPubSubServiceClient, WebPubSubServiceClientOptions>> configureClientBuilder parameter of the AddAzureWebPubSubHub method. For example, to set the client ID for this client:

builder.AddAzureWebPubSubServiceClient(
    "wps",
    configureClientBuilder: clientBuilder => 
        clientBuilder.ConfigureOptions(options => options.Retry.MaxRetries = 5));

Health checks

By default, .NET Aspire components enable health checks for all services. For more information, see .NET Aspire components overview.

The .NET Aspire Azure Web PubSub component handles exposes a configurable health check that reports as healthy, when the client can successfully connect to the Azure Web PubSub service.

Observability and telemetry

.NET Aspire components automatically set up Logging, Tracing, and Metrics configurations, which are sometimes known as the pillars of observability. For more information about component observability and telemetry, see .NET Aspire components overview. Depending on the backing service, some components may only support some of these features. For example, some components support logging and tracing, but not metrics. Telemetry features can also be disabled using the techniques presented in the Configuration section.

Logging

The .NET Aspire Azure Web PubSub component uses the following log categories:

  • Azure
  • Azure.Core
  • Azure.Identity
  • Azure.Messaging.WebPubSub

Tracing

The .NET Aspire Azure Web PubSub component will emit the following tracing activities using OpenTelemetry:

  • "Azure.Messaging.WebPubSub.*"

Metrics

The .NET Aspire Azure Web PubSub component currently doesn't support metrics by default due to limitations with the Azure SDK for .NET. If that changes in the future, this section will be updated to reflect those changes.

See also