Convert EverythingServer to use Streamable HTTP (#709)

* Convert EverythingServer to use Streamable HTTP

* Apply suggestion from @halter73

Co-authored-by: Stephen Halter <halter73@gmail.com>

---------

Co-authored-by: Stephen Halter <halter73@gmail.com>

samples/EverythingServer/EverythingServer.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
     <TargetFramework>net9.0</TargetFramework>
@@ -8,14 +8,13 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Extensions.Hosting" />
     <PackageReference Include="OpenTelemetry.Exporter.OpenTelemetryProtocol" />
     <PackageReference Include="OpenTelemetry.Extensions.Hosting" />
     <PackageReference Include="OpenTelemetry.Instrumentation.Http" />
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\..\src\ModelContextProtocol\ModelContextProtocol.csproj" />
+    <ProjectReference Include="..\..\src\ModelContextProtocol.AspNetCore\ModelContextProtocol.AspNetCore.csproj" />
   </ItemGroup>
 
 </Project>

samples/EverythingServer/EverythingServer.http

@@ -0,0 +1,77 @@
+@HostAddress = http://localhost:3001
+
+POST {{HostAddress}}/
+Accept: application/json, text/event-stream
+Content-Type: application/json
+
+{
+    "jsonrpc": "2.0",
+    "id": 1,
+    "method": "initialize",
+    "params": {
+        "clientInfo": {
+            "name": "RestClient",
+            "version": "0.1.0"
+        },
+        "capabilities": {},
+        "protocolVersion": "2025-06-18"
+    }
+}
+
+###
+
+@SessionId = ZwwM0VFEtKNOMBsP8D2VzQ
+
+POST {{HostAddress}}/
+Accept: application/json, text/event-stream
+Content-Type: application/json
+MCP-Protocol-Version: 2025-06-18
+Mcp-Session-Id: {{SessionId}}
+
+{
+    "jsonrpc": "2.0",
+    "id": 2,
+    "method": "resources/list"
+}
+
+###
+
+@resource_uri = test://direct/text/resource
+
+POST {{HostAddress}}/
+Accept: application/json, text/event-stream
+Content-Type: application/json
+MCP-Protocol-Version: 2025-06-18
+Mcp-Session-Id: {{SessionId}}
+
+{
+    "jsonrpc": "2.0",
+    "id": 3,
+    "method": "resources/subscribe",
+    "params": {
+        "uri": "{{resource_uri}}"
+    }
+}
+
+###
+
+POST {{HostAddress}}/
+Accept: application/json, text/event-stream
+Content-Type: application/json
+MCP-Protocol-Version: 2025-06-18
+Mcp-Session-Id: {{SessionId}}
+
+{
+    "jsonrpc": "2.0",
+    "id": 4,
+    "method": "resources/unsubscribe",
+    "params": {
+        "uri": "{{resource_uri}}"
+    }
+}
+
+###
+
+DELETE {{HostAddress}}/
+MCP-Protocol-Version: 2025-06-18
+Mcp-Session-Id: {{SessionId}}

samples/EverythingServer/LoggingUpdateMessageSender.cs

@@ -5,7 +5,7 @@ using ModelContextProtocol.Server;
 
 namespace EverythingServer;
 
-public class LoggingUpdateMessageSender(McpServer server, Func<LoggingLevel> getMinLevel) : BackgroundService
+public class LoggingUpdateMessageSender(McpServer server) : BackgroundService
 {
     readonly Dictionary<LoggingLevel, string> _loggingLevelMap = new()
     {
@@ -23,15 +23,15 @@ public class LoggingUpdateMessageSender(McpServer server, Func<LoggingLevel> get
     {
         while (!stoppingToken.IsCancellationRequested)
         {
-            var newLevel = (LoggingLevel)Random.Shared.Next(_loggingLevelMap.Count);
+            var msgLevel = (LoggingLevel)Random.Shared.Next(_loggingLevelMap.Count);
 
             var message = new
                 {
-                    Level = newLevel.ToString().ToLower(),
+                    Level = msgLevel.ToString().ToLower(),
-                    Data = _loggingLevelMap[newLevel],
+                    Data = _loggingLevelMap[msgLevel],
                 };
 
-            if (newLevel > getMinLevel())
+            if (msgLevel > server.LoggingLevel)
             {
                 await server.SendNotificationAsync("notifications/message", message, cancellationToken: stoppingToken);
             }

samples/EverythingServer/Program.cs

@@ -3,9 +3,6 @@ using EverythingServer.Prompts;
 using EverythingServer.Resources;
 using EverythingServer.Tools;
 using Microsoft.Extensions.AI;
-using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.Hosting;
-using Microsoft.Extensions.Logging;
 using ModelContextProtocol;
 using ModelContextProtocol.Protocol;
 using ModelContextProtocol.Server;
@@ -14,20 +11,46 @@ using OpenTelemetry.Logs;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.Resources;
 using OpenTelemetry.Trace;
+using System.Collections.Concurrent;
 
-var builder = Host.CreateApplicationBuilder(args);
+var builder = WebApplication.CreateBuilder(args);
-builder.Logging.AddConsole(consoleLogOptions =>
-{
-    // Configure all logs to go to stderr
-    consoleLogOptions.LogToStandardErrorThreshold = LogLevel.Trace;
-});
 
-HashSet<string> subscriptions = [];
+// Dictionary of session IDs to a set of resource URIs they are subscribed to
-var _minimumLoggingLevel = LoggingLevel.Debug;
+// The value is a ConcurrentDictionary used as a thread-safe HashSet
+// because .NET does not have a built-in concurrent HashSet
+ConcurrentDictionary<string, ConcurrentDictionary<string, byte>> subscriptions = new();
 
 builder.Services
     .AddMcpServer()
-    .WithStdioServerTransport()
+    .WithHttpTransport(options =>
+    {
+        // Add a RunSessionHandler to remove all subscriptions for the session when it ends
+        options.RunSessionHandler = async (httpContext, mcpServer, token) =>
+        {
+            if (mcpServer.SessionId == null)
+            {
+                // There is no sessionId if the serverOptions.Stateless is true
+                await mcpServer.RunAsync(token);
+                return;
+            }
+            try
+            {
+                subscriptions[mcpServer.SessionId] = new ConcurrentDictionary<string, byte>();
+                // Start an instance of SubscriptionMessageSender for this session
+                using var subscriptionSender = new SubscriptionMessageSender(mcpServer, subscriptions[mcpServer.SessionId]);
+                await subscriptionSender.StartAsync(token);
+                // Start an instance of LoggingUpdateMessageSender for this session
+                using var loggingSender = new LoggingUpdateMessageSender(mcpServer);
+                await loggingSender.StartAsync(token);
+                await mcpServer.RunAsync(token);
+            }
+            finally
+            {
+                // This code runs when the session ends
+                subscriptions.TryRemove(mcpServer.SessionId, out _);
+            }
+        };
+    })
     .WithTools<AddTool>()
     .WithTools<AnnotatedMessageTool>()
     .WithTools<EchoTool>()
@@ -40,11 +63,13 @@ builder.Services
     .WithResources<SimpleResourceType>()
     .WithSubscribeToResourcesHandler(async (ctx, ct) =>
     {
-        var uri = ctx.Params?.Uri;
+        if (ctx.Server.SessionId == null)
-
-        if (uri is not null)
         {
-            subscriptions.Add(uri);
+            throw new McpException("Cannot add subscription for server with null SessionId");
+        }
+        if (ctx.Params?.Uri is { } uri)
+        {
+            subscriptions[ctx.Server.SessionId].TryAdd(uri, 0);
 
             await ctx.Server.SampleAsync([
                 new ChatMessage(ChatRole.System, "You are a helpful test server"),
@@ -62,10 +87,13 @@ builder.Services
     })
     .WithUnsubscribeFromResourcesHandler(async (ctx, ct) =>
     {
-        var uri = ctx.Params?.Uri;
+        if (ctx.Server.SessionId == null)
-        if (uri is not null)
         {
-            subscriptions.Remove(uri);
+            throw new McpException("Cannot remove subscription for server with null SessionId");
+        }
+        if (ctx.Params?.Uri is { } uri)
+        {
+            subscriptions[ctx.Server.SessionId].TryRemove(uri, out _);
         }
         return new EmptyResult();
     })
@@ -126,13 +154,13 @@ builder.Services
             throw new McpProtocolException("Missing required argument 'level'", McpErrorCode.InvalidParams);
         }
 
-        _minimumLoggingLevel = ctx.Params.Level;
+        // The SDK updates the LoggingLevel field of the IMcpServer
 
         await ctx.Server.SendNotificationAsync("notifications/message", new
         {
             Level = "debug",
             Logger = "test-server",
-            Data = $"Logging level set to {_minimumLoggingLevel}",
+            Data = $"Logging level set to {ctx.Params.Level}",
         }, cancellationToken: ct);
 
         return new EmptyResult();
@@ -145,10 +173,8 @@ builder.Services.AddOpenTelemetry()
     .WithLogging(b => b.SetResourceBuilder(resource))
     .UseOtlpExporter();
 
-builder.Services.AddSingleton(subscriptions);
+var app = builder.Build();
-builder.Services.AddHostedService<SubscriptionMessageSender>();
-builder.Services.AddHostedService<LoggingUpdateMessageSender>();
 
-builder.Services.AddSingleton<Func<LoggingLevel>>(_ => () => _minimumLoggingLevel);
+app.MapMcp();
 
-await builder.Build().RunAsync();
+app.Run();

samples/EverythingServer/Properties/launchSettings.json

@@ -0,0 +1,21 @@
+{
+  "$schema": "https://json.schemastore.org/launchsettings.json",
+  "profiles": {
+    "http": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "applicationUrl": "http://localhost:3001",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development",
+      }
+    },
+    "https": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "applicationUrl": "https://localhost:7133;http://localhost:3001",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development",
+      }
+    }
+  }
+}

samples/EverythingServer/SubscriptionMessageSender.cs

@@ -1,14 +1,14 @@
-using Microsoft.Extensions.Hosting;
+using System.Collections.Concurrent;
 using ModelContextProtocol;
 using ModelContextProtocol.Server;
 
-internal class SubscriptionMessageSender(McpServer server, HashSet<string> subscriptions) : BackgroundService
+internal class SubscriptionMessageSender(McpServer server, ConcurrentDictionary<string, byte> subscriptions) : BackgroundService
 {
     protected override async Task ExecuteAsync(CancellationToken stoppingToken)
     {
         while (!stoppingToken.IsCancellationRequested)
         {
-            foreach (var uri in subscriptions)
+            foreach (var uri in subscriptions.Keys)
             {
                 await server.SendNotificationAsync("notifications/resource/updated",
                     new

samples/EverythingServer/appsettings.Development.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

samples/EverythingServer/appsettings.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*"
+}