WN Update: SignalR ActivitySource (#34183)

* WN Update SignalR ActivitySource

Review suggestion by tdykstra

Co-authored-by: Tom Dykstra <[email protected]>

* Removed dupe code in program.cs

* Updated code highlight to match code change

---------

Co-authored-by: Tom Dykstra <[email protected]>

Author: wadepickett

aspnetcore/release-notes/aspnetcore-9.0.md

@@ -4,7 +4,7 @@ author: rick-anderson
 description: Learn about the new features in ASP.NET Core 9.0.
 ms.author: riande
 ms.custom: mvc
-ms.date: 10/07/2024
+ms.date: 11/19/2024
 uid: aspnetcore-9
 ---
 # What's new in ASP.NET Core 9.0

aspnetcore/release-notes/aspnetcore-9/_static/signalr-activites-events.png renamed to aspnetcore/release-notes/aspnetcore-9/_static/signalr-activities-events.png

@@ -1,6 +1,10 @@
 ### Improved Activities for SignalR
 
-SignalR now has an ActivitySource named `Microsoft.AspNetCore.SignalR.Server` that emits events for hub method calls:
+SignalR now has an ActivitySource for both the hub server and client.
+
+#### .NET SignalR server ActivitySource
+
+The SignalR ActivitySource named `Microsoft.AspNetCore.SignalR.Server` emits events for hub method calls:
 
 * Every method is its own activity, so anything that emits an activity during the hub method call is under the hub method activity.
 * Hub method activities don't have a parent. This means they are not bundled under the long-running SignalR connection.
@@ -15,29 +19,19 @@ The following example uses the [.NET Aspire dashboard](/dotnet/aspire/fundamenta
 
 Add the following startup code to the `Program.cs` file:
 
-```csharp
-// Set OTEL_EXPORTER_OTLP_ENDPOINT environment variable depending on where your OTEL endpoint is
-var builder = WebApplication.CreateBuilder(args);
+[!code-csharp[](~/release-notes/aspnetcore-9/samples/SignalRChatTraceExample/Program.cs?name=snippet_trace_signalr_server&highlight=1,10-23)]
+
+The following is example output from the Aspire Dashboard:
 
-builder.Services.AddRazorPages();
-builder.Services.AddSignalR();
+:::image type="content" source="~/release-notes/aspnetcore-9/_static/signalr-activities-events.png" alt-text="Activity list for SignalR Hub method call events":::
 
-builder.Services.AddOpenTelemetry()
-    .WithTracing(tracing =>
-    {
-        if (builder.Environment.IsDevelopment())
-        {
-            // We want to view all traces in development
-            tracing.SetSampler(new AlwaysOnSampler());
-        }
+#### .NET SignalR client ActivitySource
 
-        tracing.AddAspNetCoreInstrumentation();
-        tracing.AddSource("Microsoft.AspNetCore.SignalR.Server");
-    });
+The SignalR ActivitySource named `Microsoft.AspNetCore.SignalR.Client` emits events for a SignalR client:
 
-builder.Services.ConfigureOpenTelemetryTracerProvider(tracing => tracing.AddOtlpExporter());
-```
+* The .NET SignalR client has an `ActivitySource` named `Microsoft.AspNetCore.SignalR.Client`. Hub invocations now create a client span. Note that other SignalR clients, such as the JavaScript client, don't support tracing. This feature will be added to more clients in future releases.
+* Hub invocations on the client and server support [context propagation](https://opentelemetry.io/docs/concepts/context-propagation/). Propagating the trace context enables true distributed tracing. It's now possible to see invocations flow from the client to the server and back.
 
-The following is example output from the Aspire Dashboard:
+Here's how these new activities look in the [.NET Aspire dashboard](https://learn.microsoft.com/dotnet/aspire/fundamentals/dashboard/overview?tabs=bash#standalone-mode):
 
-:::image type="content" source="~/release-notes/aspnetcore-9/_static/signalr-activites-events.png" alt-text="Activity list for SignalR Hub method call events":::
+![SignalR distributed tracing in Aspire dashboard](~/release-notes/aspnetcore-9/_static/signalr-distributed-tracing-aspire-dashboard.png) 

aspnetcore/release-notes/aspnetcore-9/includes/signalr-distributed-tracing-improvements.md

@@ -0,0 +1,12 @@
+using Microsoft.AspNetCore.SignalR;
+
+namespace SignalRChat.Hubs
+{
+    public class ChatHub : Hub
+    {
+        public async Task SendMessage(string user, string message)
+        {
+            await Clients.All.SendAsync("ReceiveMessage", user, message);
+        }
+    }
+}

aspnetcore/release-notes/aspnetcore-9/includes/signalrActivities.md

@@ -0,0 +1,26 @@
+@page
+@model ErrorModel
+@{
+    ViewData["Title"] = "Error";
+}
+
+<h1 class="text-danger">Error.</h1>
+<h2 class="text-danger">An error occurred while processing your request.</h2>
+
+@if (Model.ShowRequestId)
+{
+    <p>
+        <strong>Request ID:</strong> <code>@Model.RequestId</code>
+    </p>
+}
+
+<h3>Development Mode</h3>
+<p>
+    Swapping to the <strong>Development</strong> environment displays detailed information about the error that occurred.
+</p>
+<p>
+    <strong>The Development environment shouldn't be enabled for deployed applications.</strong>
+    It can result in displaying sensitive information from exceptions to end users.
+    For local debugging, enable the <strong>Development</strong> environment by setting the <strong>ASPNETCORE_ENVIRONMENT</strong> environment variable to <strong>Development</strong>
+    and restarting the app.
+</p>

aspnetcore/release-notes/aspnetcore-9/samples/SignalRChatTraceExample/ChatHub/ChatHub.cs

@@ -0,0 +1,28 @@
+using System.Diagnostics;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+
+namespace SignalRChat.Pages
+{
+    [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
+    [IgnoreAntiforgeryToken]
+    public class ErrorModel : PageModel
+    {
+        public string? RequestId { get; set; }
+
+        public bool ShowRequestId => !string.IsNullOrEmpty(RequestId);
+
+        private readonly ILogger<ErrorModel> _logger;
+
+        public ErrorModel(ILogger<ErrorModel> logger)
+        {
+            _logger = logger;
+        }
+
+        public void OnGet()
+        {
+            RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier;
+        }
+    }
+
+}

aspnetcore/release-notes/aspnetcore-9/samples/SignalRChatTraceExample/Pages/Error.cshtml

@@ -0,0 +1,28 @@
+@page
+<div class="container">
+    <div class="row p-1">
+        <div class="col-1">User</div>
+        <div class="col-5"><input type="text" id="userInput" /></div>
+    </div>
+    <div class="row p-1">
+        <div class="col-1">Message</div>
+        <div class="col-5"><input type="text" class="w-100" id="messageInput" /></div>
+    </div>
+    <div class="row p-1">
+        <div class="col-6 text-end">
+            <input type="button" id="sendButton" value="Send Message" />
+        </div>
+    </div>
+    <div class="row p-1">
+        <div class="col-6">
+            <hr />
+        </div>
+    </div>
+    <div class="row p-1">
+        <div class="col-6">
+            <ul id="messagesList"></ul>
+        </div>
+    </div>
+</div>
+<script src="~/js/signalr/dist/browser/signalr.js"></script>
+<script src="~/js/chat.js"></script>

aspnetcore/release-notes/aspnetcore-9/samples/SignalRChatTraceExample/Pages/Error.cshtml.cs

@@ -0,0 +1,20 @@
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.RazorPages;
+
+namespace SignalRChat.Pages
+{
+    public class IndexModel : PageModel
+    {
+        private readonly ILogger<IndexModel> _logger;
+
+        public IndexModel(ILogger<IndexModel> logger)
+        {
+            _logger = logger;
+        }
+
+        public void OnGet()
+        {
+
+        }
+    }
+}

aspnetcore/release-notes/aspnetcore-9/samples/SignalRChatTraceExample/Pages/Index.cshtml

@@ -0,0 +1,8 @@
+@page
+@model PrivacyModel
+@{
+    ViewData["Title"] = "Privacy Policy";
+}
+<h1>@ViewData["Title"]</h1>
+
+<p>Use this page to detail your site's privacy policy.</p>