SSE return types /2

Author: Rick-Anderson

aspnetcore/fundamentals/minimal-apis/10.0-samples/MinimalServerSentEvents/HeartRateRecord.cs

@@ -0,0 +1,4 @@
+public record HeartRateRecord(DateTime Timestamp, int HeartRate)
+{
+    public static HeartRateRecord Create(int heartRate) => new(DateTime.UtcNow, heartRate);
+}

aspnetcore/fundamentals/minimal-apis/10.0-samples/MinimalServerSentEvents/Program.cs

@@ -25,13 +25,13 @@ async IAsyncEnumerable<string> GetHeartRate(
 // <snippet_json>
 app.MapGet("/json-item", (CancellationToken cancellationToken) =>
 {
-    async IAsyncEnumerable<HearRate> GetHeartRate(
+    async IAsyncEnumerable<HeartRateRecord> GetHeartRate(
         [EnumeratorCancellation] CancellationToken cancellationToken)
     {
         while (!cancellationToken.IsCancellationRequested)
         {
             var heartRate = Random.Shared.Next(60, 100);
-            yield return HearRate.Create(heartRate);
+            yield return HeartRateRecord.Create(heartRate);
             await Task.Delay(2000, cancellationToken);
         }
     }
@@ -64,7 +64,3 @@ async IAsyncEnumerable<SseItem<int>> GetHeartRate(
 
 app.Run();
 
-public record HearRate(DateTime Timestamp, int HeartRate)
-{
-    public static HearRate Create(int heartRate) => new(DateTime.UtcNow, heartRate);
-}

aspnetcore/release-notes/aspnetcore-10/includes/sse.md

@@ -0,0 +1,16 @@
+### Support for Server-Sent Events (SSE)
+
+ASP.NET Core now supports returning a [ServerSentEvents](xref:System.Net.ServerSentEvents) result using the [TypedResults.ServerSentEvents](https://source.dot.net/#Microsoft.AspNetCore.Http.Results/TypedResults.cs,051e6796e1492f84) API. This feature is supported in both Minimal APIs and controller-based apps.
+
+Server-Sent Events is a server push technology that allows a server to send a stream of event messages to a client over a single HTTP connection. In .NET the event messages are represented as [`SseItem<T`>`](/dotnet/api/system.net.serversentevents.sseitem-1) objects, which may contain an event type, an ID, and a data payload of type `T`.
+
+The [TypedResults](xref:Microsoft.AspNetCore.Http.TypedResults) class has a new static method called [ServerSentEvents](https://source.dot.net/#Microsoft.AspNetCore.Http.Results/TypedResults.cs,ceb980606eb9e295) that can be used to return a `ServerSentEvents` result. The first parameter to this method is an `IAsyncEnumerable<SseItem<T>>` that represents the stream of event messages to be sent to the client.
+
+The following example illustrates how to use the  `TypedResults.ServerSentEvents` API to return a stream of heart rate events as JSON objects to the client:
+
+:::code language="csharp" source="~/fundamentals/minimal-apis/10.0-samples/MinimalServerSentEvents/Program.cs" id="snippet_json" :::
+
+For more information, see:
+
+- 
+-  [Server-Sent Events](https://developer.mozilla.org/docs/Web/API/Server-sent_events) on MDN.

aspnetcore/web-api/action-return-types/samples/10/ControllerSSE/ControllerSSE.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="10.0.0-*" />
+  </ItemGroup>
+
+</Project>

aspnetcore/web-api/action-return-types/samples/10/ControllerSSE/ControllerSSE.http

@@ -0,0 +1,15 @@
+@baseUrl = http://localhost:5201/HeartRate
+
+### Connect to SSE stream
+# This request will open an SSE connection that stays open
+GET {{baseUrl}}/string-item
+Accept: text/event-stream
+
+###
+GET {{baseUrl}}/json-item
+Accept: text/event-stream
+
+###
+
+GET {{baseUrl}}/sse-item
+Accept: text/event-stream

aspnetcore/web-api/action-return-types/samples/10/ControllerSSE/Controllers/HeartRateController.cs

@@ -0,0 +1,68 @@
+using Microsoft.AspNetCore.Mvc;
+using System.Runtime.CompilerServices;
+using System.Net.ServerSentEvents;
+
+[ApiController]
+[Route("[controller]")]
+
+public class HeartRateController : ControllerBase
+{
+    // /HeartRate/json-item
+    [HttpGet("json-item")]
+    public IResult GetHeartRateJson(CancellationToken cancellationToken)
+    {
+        async IAsyncEnumerable<HearRate> StreamHeartRates(
+            [EnumeratorCancellation] CancellationToken cancellationToken)
+        {
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                var heartRate = Random.Shared.Next(60, 100);
+                yield return HearRate.Create(heartRate);
+                await Task.Delay(2000, cancellationToken);
+            }
+        }
+
+        return TypedResults.ServerSentEvents(StreamHeartRates(cancellationToken), eventType: "heartRate");
+    }
+
+    // /HeartRate/string-item
+    [HttpGet("string-item")]
+
+    public IResult GetHeartRateString(CancellationToken cancellationToken)
+    {
+        async IAsyncEnumerable<string> GetHeartRate(
+            [EnumeratorCancellation] CancellationToken cancellationToken)
+        {
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                var heartRate = Random.Shared.Next(60, 100);
+                yield return $"Hear Rate: {heartRate} bpm";
+                await Task.Delay(2000, cancellationToken);
+            }
+        }
+
+        return TypedResults.ServerSentEvents(GetHeartRate(cancellationToken), eventType: "heartRate");
+    }
+
+    // /HeartRate/sse-item
+    [HttpGet("sse-item")]
+
+    public IResult GetHeartRateSSE(CancellationToken cancellationToken)
+    {
+        async IAsyncEnumerable<SseItem<int>> GetHeartRate(
+            [EnumeratorCancellation] CancellationToken cancellationToken)
+        {
+            while (!cancellationToken.IsCancellationRequested)
+            {
+                var heartRate = Random.Shared.Next(60, 100);
+                yield return new SseItem<int>(heartRate, eventType: "heartRate")
+                {
+                    ReconnectionInterval = TimeSpan.FromMinutes(1)
+                };
+                await Task.Delay(2000, cancellationToken);
+            }
+        }
+
+        return TypedResults.ServerSentEvents(GetHeartRate(cancellationToken));
+    }
+}

aspnetcore/web-api/action-return-types/samples/10/ControllerSSE/HearRate.cs

@@ -0,0 +1,4 @@
+public record HearRate(DateTime Timestamp, int HeartRate)
+{
+    public static HearRate Create(int heartRate) => new(DateTime.UtcNow, heartRate);
+}

aspnetcore/web-api/action-return-types/samples/10/ControllerSSE/Program.cs

@@ -0,0 +1,28 @@
+
+var builder = WebApplication.CreateBuilder(args);
+
+// Add services to the container.
+
+builder.Services.AddControllers();
+// Learn more about configuring OpenAPI at https://aka.ms/aspnet/openapi
+builder.Services.AddOpenApi();
+
+var app = builder.Build();
+
+// Configure the HTTP request pipeline.
+if (app.Environment.IsDevelopment())
+{
+    app.MapOpenApi();
+}
+
+app.UseHttpsRedirection();
+
+app.UseAuthorization();
+
+
+app.MapControllers();
+
+app.MapGet("/", () => Results.Redirect("/HeartRate/json-item"));
+
+
+app.Run();