Blazor WASM configure SignalR client (#18742)

aspnetcore/blazor/hosting-model-configuration.md

@@ -5,7 +5,7 @@ description: Learn about Blazor hosting model configuration, including how to in
 monikerRange: '>= aspnetcore-3.1'
 ms.author: riande
 ms.custom: mvc
-ms.date: 05/28/2020
+ms.date: 06/10/2020
 no-loc: [Blazor, "Identity", "Let's Encrypt", Razor, SignalR]
 uid: blazor/hosting-model-configuration
 ---
@@ -281,6 +281,37 @@ For more information on how background updates are handled by PWAs, see <xref:bl
 
 For information on Blazor WebAssembly logging support, see <xref:fundamentals/logging/index#create-logs-in-blazor>.
 
+### SignalR cross-origin negotiation for authentication
+
+To configure SignalR's underlying client to send credentials, such as cookies or HTTP authentication headers:
+
+* Use <xref:Microsoft.AspNetCore.Components.WebAssembly.Http.WebAssemblyHttpRequestMessageExtensions.SetBrowserRequestCredentials%2A> to set <xref:Microsoft.AspNetCore.Components.WebAssembly.Http.BrowserRequestCredentials.Include> on cross-origin [fetch](https://developer.mozilla.org/docs/Web/API/Fetch_API/Using_Fetch) requests:
+
+  ```csharp
+  public class IncludeRequestCredentialsMessagHandler : DelegatingHandler
+  {
+      protected override Task<HttpResponseMessage> SendAsync(
+          HttpRequestMessage request, CancellationToken cancellationToken)
+      {
+          request.SetBrowserRequestCredentials(BrowserRequestCredentials.Include);
+          return base.SendAsync(request, cancellationToken);
+      }
+  }
+  ```
+
+* Assign the <xref:System.Net.Http.HttpMessageHandler> to the <xref:Microsoft.AspNetCore.Http.Connections.Client.HttpConnectionOptions.HttpMessageHandlerFactory> option:
+
+  ```csharp
+  var client = new HubConnectionBuilder()
+      .WithUrl(new Uri("http://signalr.example.com"), options =>
+      {
+          options.HttpMessageHandlerFactory = innerHandler => 
+              new IncludeRequestCredentialsMessagHandler { InnerHandler = innerHandler };
+      }).Build();
+  ```
+
+For more information, see <xref:signalr/configuration#configure-additional-options>.
+
 ## Blazor Server
 
 ### Reflect the connection state in the UI

aspnetcore/blazor/progressive-web-app.md

@@ -5,7 +5,7 @@ description: Learn how to build a Blazor-based Progressive Web Application (PWA)
 monikerRange: '>= aspnetcore-3.1'
 ms.author: riande
 ms.custom: mvc
-ms.date: 06/09/2020
+ms.date: 06/10/2020
 no-loc: [Blazor, "Identity", "Let's Encrypt", Razor, SignalR]
 uid: blazor/progressive-web-app
 ---
@@ -281,3 +281,7 @@ The [CarChecker](https://github.com/SteveSandersonMS/CarChecker) sample app demo
 * `OfflineAccountClaimsPrincipalFactory` (*Client/Data/OfflineAccountClaimsPrincipalFactory.cs*)
 * `LocalVehiclesStore` (*Client/Data/LocalVehiclesStore.cs*)
 * `LoginStatus` component (*Client/Shared/LoginStatus.razor*)
+
+## Additional resources
+
+* [SignalR cross-origin negotiation for authentication](xref:blazor/hosting-model-configuration#signalr-cross-origin-negotiation-for-authentication)

aspnetcore/tutorials/signalr-blazor-webassembly.md

@@ -5,7 +5,7 @@ description: Create a chat app that uses ASP.NET Core SignalR with Blazor WebAss
 monikerRange: '>= aspnetcore-3.1'
 ms.author: riande
 ms.custom: mvc
-ms.date: 05/19/2020
+ms.date: 06/10/2020
 no-loc: [Blazor, "Identity", "Let's Encrypt", Razor, SignalR]
 uid: tutorials/signalr-blazor-webassembly
 ---
@@ -285,3 +285,4 @@ To learn more about building Blazor apps, see the Blazor documentation:
 ## Additional resources
 
 * <xref:signalr/introduction>
+* [SignalR cross-origin negotiation for authentication](xref:blazor/hosting-model-configuration#signalr-cross-origin-negotiation-for-authentication)