Add blurb about dist tracing (Azure#17059)

- Addresses Azure#16238
- Update LineCounter sample app to show usage of Event Grid
- Update LineCounter README to include a screenshot of Azure Monitor
- Update Distributed Tracing section in Diagnostics readme to link to LineCounter.
- Also add in DI extension methods.

samples/linecounter/Controllers/HomeController.cs

@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Threading.Tasks;
+using Azure.Messaging.EventGrid;
 using Azure.Messaging.EventHubs;
 using Azure.Messaging.EventHubs.Producer;
 using Azure.Storage.Blobs;
@@ -18,12 +19,18 @@ public class HomeController : Controller
         private readonly ILogger<HomeController> _logger;
         private readonly BlobContainerClient _blobContainerClient;
         private readonly EventHubProducerClient _uploadsProducer;
+        private readonly EventGridPublisherClient _publisherClient;
 
-        public HomeController(ILogger<HomeController> logger, BlobServiceClient blobServiceClient, IAzureClientFactory<EventHubProducerClient> clientFactory)
+        public HomeController(
+            ILogger<HomeController> logger,
+            BlobServiceClient blobServiceClient,
+            IAzureClientFactory<EventHubProducerClient> clientFactory,
+            EventGridPublisherClient publisherClient)
         {
             _logger = logger;
             _blobContainerClient = blobServiceClient.GetBlobContainerClient("uploads");
             _uploadsProducer = clientFactory.CreateClient("Uploads");
+            _publisherClient = publisherClient;
         }
 
         public IActionResult Index()
@@ -60,7 +67,7 @@ public async Task<string> Status(string name)
         {
             var properties = await _blobContainerClient.GetBlobClient(name).GetPropertiesAsync();
             properties.Value.Metadata.TryGetValue("whitespacecount", out var count);
-
+            await _publisherClient.SendEventsAsync(new CloudEvent[] { new CloudEvent("https://www.contoso.com/LineCounter", "LineCounter.Status.Viewed", name) });
             return count ?? "-1";
         }
     }

samples/linecounter/LineCounter.csproj

@@ -13,4 +13,7 @@
   <ItemGroup>
     <Folder Include="Connected Services\" />
   </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\sdk\eventgrid\Azure.Messaging.EventGrid\src\Azure.Messaging.EventGrid.csproj" />
+  </ItemGroup>
 </Project>

samples/linecounter/README.md

@@ -6,15 +6,16 @@ products:
 - azure
 - azure-storage
 - azure-event-hubs
+- azure-event-grid
 urlFragment: line-counter
 name: LineCounter
-description: Sample that illustrates using Storage and Event Hubs clients along with ASP.NET Core integration, distributed tracing and hosted services.
+description: Sample that illustrates using Storage, Event Hubs, and Event Grid clients along with ASP.NET Core integration, distributed tracing and hosted services.
 ---
 
 # LineCounter
-This is a sample app that illustrates using Storage and Event Hubs clients along with ASP.NET Core integration, distributed tracing and hosted services.
+This is a sample app that illustrates using Storage, Event Hubs, and Event Grid clients along with ASP.NET Core integration, distributed tracing and hosted services.
 It allows users to upload a file to a blob, which triggers an Event Hubs event containing the file name. 
-The Event Hubs Processor receives the event, and then the app downloads the blob and counts the number of lines in the file.
+The Event Hubs Processor receives the event, and then the app downloads the blob and counts the number of lines in the file. The app displays a link to a page containing the line count. When the link is clicked, a CloudEvent containing the name of the file is published using Event Grid.
 
 # Configuration
 
@@ -32,6 +33,11 @@ To run the sample set the following configuration properties using manage user s
   "Results": {
     "connectionString": "...",
     "eventHubName": "..."
+  },
+  "Notification": {
+    "endpoint": "...",
+    "credential": {
+      "key": "..."
   }
 }
 ```
@@ -45,3 +51,7 @@ To light up App Insights, add the InstrumentationKey key and value to the Applic
   }
 }
 ```
+
+# Azure Monitor
+You can view an end-to-end transaction in the portal by going to your App. Click on the Search icon, and then click See all data.
+After selecting a grouped result, you will be able to see a timeline of the grouped requests: ![Monitor](assets/monitor.PNG).

samples/linecounter/Startup.cs

@@ -29,6 +29,7 @@ public void ConfigureServices(IServiceCollection services)
                     builder.AddEventHubProducerClient(Configuration.GetSection("Uploads")).WithName("Uploads");
 
                     builder.AddEventHubProducerClient(Configuration.GetSection("Results")).WithName("Results");
+                    builder.AddEventGridPublisherClient(Configuration.GetSection("Notification"));
                 });
             services.AddApplicationInsightsTelemetry();
         }

sdk/core/Azure.Core/samples/Diagnostics.md

@@ -102,6 +102,9 @@ To setup ApplicationInsights tracking for your application follow the [Start Mon
 
 Follow the [OpenTelemetry configuration guide](https://github.com/open-telemetry/opentelemetry-dotnet#configuration-with-microsoftextensionsdependencyinjection) to configure collecting distribute tracing event collection using the OpenTelemetry library.
 
+### Sample
+To see an example of distributed tracing in action, take a look at our [sample app](https://github.com/Azure/azure-sdk-for-net/blob/master/samples/linecounter/README.md) that combines several Azure SDKs.
+
 ## Setting x-ms-client-request-id value sent with requests
 
 By default x-ms-client-request-id header gets a unique value per client method call. If you would like to use a specific value for a set of requests use the `HttpPipeline.CreateClientRequestIdScope` method.

sdk/eventgrid/Azure.Messaging.EventGrid/README.md

@@ -231,6 +231,9 @@ foreach (EventGridEvent egEvent in egEvents)
 ### Setting up console logging
 You can also easily [enable console logging](https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/core/Azure.Core/samples/Diagnostics.md#logging) if you want to dig deeper into the requests you're making against the service.
 
+### Distributed Tracing
+The Event Grid library supports distributing tracing out of the box. In order to adhere to the CloudEvents specification's [guidance](https://github.com/cloudevents/spec/blob/master/extensions/distributed-tracing.md) on distributing tracing, the library will set the `traceparent` and `tracestate` on the [ExtensionAttributes](https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/eventgrid/Azure.Messaging.EventGrid/src/Customization/CloudEvent.cs#L126) of a `CloudEvent` when distributed tracing is enabled. To learn more about how to enable distributed tracing in your application, take a look at the Azure SDK [distributed tracing documentation](https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/core/Azure.Core/samples/Diagnostics.md#Distributed-tracing).
+
 ## Next steps
 
 View more https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/eventgrid/Azure.Messaging.EventGrid/samples here for common usages of the Event Grid client library: [Event Grid Samples](https://github.com/Azure/azure-sdk-for-net/blob/master/sdk/eventgrid/Azure.Messaging.EventGrid/samples).

sdk/eventgrid/Azure.Messaging.EventGrid/api/Azure.Messaging.EventGrid.netstandard2.0.cs

@@ -1341,3 +1341,12 @@ internal WebSlotSwapWithPreviewStartedEventData() { }
         public string Verb { get { throw null; } }
     }
 }
+namespace Microsoft.Extensions.Azure
+{
+    public static partial class EventGridPublisherClientBuilderExtensions
+    {
+        public static Azure.Core.Extensions.IAzureClientBuilder<Azure.Messaging.EventGrid.EventGridPublisherClient, Azure.Messaging.EventGrid.EventGridPublisherClientOptions> AddEventGridPublisherClient<TBuilder>(this TBuilder builder, System.Uri endpoint, Azure.AzureKeyCredential credential) where TBuilder : Azure.Core.Extensions.IAzureClientFactoryBuilder { throw null; }
+        public static Azure.Core.Extensions.IAzureClientBuilder<Azure.Messaging.EventGrid.EventGridPublisherClient, Azure.Messaging.EventGrid.EventGridPublisherClientOptions> AddEventGridPublisherClient<TBuilder>(this TBuilder builder, System.Uri endpoint, Azure.Messaging.EventGrid.EventGridSharedAccessSignatureCredential credential) where TBuilder : Azure.Core.Extensions.IAzureClientFactoryBuilder { throw null; }
+        public static Azure.Core.Extensions.IAzureClientBuilder<Azure.Messaging.EventGrid.EventGridPublisherClient, Azure.Messaging.EventGrid.EventGridPublisherClientOptions> AddEventGridPublisherClient<TBuilder, TConfiguration>(this TBuilder builder, TConfiguration configuration) where TBuilder : Azure.Core.Extensions.IAzureClientFactoryBuilderWithConfiguration<TConfiguration> { throw null; }
+    }
+}

sdk/eventgrid/Azure.Messaging.EventGrid/src/Compatibility/EventGridPublisherClientBuilderExtensions.cs

@@ -0,0 +1,45 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using Azure;
+using Azure.Core.Extensions;
+using Azure.Messaging.EventGrid;
+
+namespace Microsoft.Extensions.Azure
+{
+    /// <summary>
+    ///    The set of extensions to add the <see cref="EventGridPublisherClient"/> type to the clients builder.
+    /// </summary>
+    public static class EventGridPublisherClientBuilderExtensions
+    {
+        /// <summary>
+        ///   Registers a <see cref="EventGridPublisherClient "/> instance with the provided <see cref="Uri"/> and <see cref="AzureKeyCredential"/>./>.
+        /// </summary>
+        public static IAzureClientBuilder<EventGridPublisherClient, EventGridPublisherClientOptions> AddEventGridPublisherClient<TBuilder>(
+            this TBuilder builder,
+            Uri endpoint,
+            AzureKeyCredential credential)
+            where TBuilder : IAzureClientFactoryBuilder =>
+            builder.RegisterClientFactory<EventGridPublisherClient, EventGridPublisherClientOptions>(options => new EventGridPublisherClient(endpoint, credential, options));
+
+        /// <summary>
+        ///   Registers a <see cref="EventGridPublisherClient "/> instance with the provided <see cref="Uri"/> and <see cref="EventGridSharedAccessSignatureCredential"/>./>.
+        /// </summary>
+        public static IAzureClientBuilder<EventGridPublisherClient, EventGridPublisherClientOptions> AddEventGridPublisherClient<TBuilder>(
+            this TBuilder builder,
+            Uri endpoint,
+            EventGridSharedAccessSignatureCredential credential)
+            where TBuilder : IAzureClientFactoryBuilder =>
+            builder.RegisterClientFactory<EventGridPublisherClient, EventGridPublisherClientOptions>(options => new EventGridPublisherClient(endpoint, credential, options));
+
+        /// <summary>
+        ///   Registers a <see cref="EventGridPublisherClient"/> instance with connection options loaded from the provided <paramref name="configuration"/> instance.
+        /// </summary>
+        public static IAzureClientBuilder<EventGridPublisherClient, EventGridPublisherClientOptions> AddEventGridPublisherClient<TBuilder, TConfiguration>(
+            this TBuilder builder,
+            TConfiguration configuration)
+            where TBuilder : IAzureClientFactoryBuilderWithConfiguration<TConfiguration> =>
+            builder.RegisterClientFactory<EventGridPublisherClient, EventGridPublisherClientOptions>(configuration);
+    }
+}