Add samples for HTTP Streamable

[vandana2015]

Add samples examples for mcp server for HTTP Streamable

[ahmar-husain]

Hi @vandana2015 I am not from MCP team but i figured this out

Server Code

• Key point to note in the server code is WithHttpTransport
• Read app.MapMcp(); code documention here

  csharp-sdk/src/ModelContextProtocol.AspNetCore/McpEndpointRouteBuilderExtensions.cs

  Line 17 in 1e8fb04

  /// Sets up endpoints for handling MCP Streamable HTTP transport.

using example.server;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddMcpServer().WithHttpTransport(option => { option.Stateless = true; }).WithToolsFromAssembly();
var app = builder.Build();
app.UseHttpsRedirection();
app.MapMcp();
app.Run();

Client
Key point to note in the client code is TransportMode = HttpTransportMode.StreamableHttp and the uri which does not have /sse

 public async Task<IEnumerable<KernelFunction>> ImportMcpTool()
 {
     var clientTransport = new SseClientTransport(
              new SseClientTransportOptions
              {
                  Endpoint = new Uri("https://localhost:7042")
                  , TransportMode = HttpTransportMode.StreamableHttp,
                  
              }
          );

     var mcpClient= await McpClientFactory.CreateAsync(clientTransport);
     var clientTools =await mcpClient.ListToolsAsync();
     return clientTools.Select(_ => _.AsKernelFunction());           
 }

[TomasHubelbauer]

There is https://github.com/modelcontextprotocol/csharp-sdk/blob/main/src/ModelContextProtocol.Core/Client/StreamableHttpClientSessionTransport.cs but it is internal.

I guess what you found @ahmar-husain is the way it is meant to be used, through the SseClientTransport (even though the streamable HTTP transport can be either JSON or SSE, not always SSE...), thanks for sharing this!

[ahmar-husain]

There is https://github.com/modelcontextprotocol/csharp-sdk/blob/main/src/ModelContextProtocol.Core/Client/StreamableHttpClientSessionTransport.cs but it is internal.

I guess what you found @ahmar-husain is the way it is meant to be used, through the SseClientTransport (even though the streamable HTTP transport can be either JSON or SSE, not always SSE...), thanks for sharing this!

hi @TomasHubelbauer ,
Here's my example: First, download and start the server. Once that's up, run the client, which is a console application. After it starts, you can give it a prompt like: "Give me the details of my booking 56135163".

NOTE The client is using Semantic Kernel and Azure OpenAI, so you’ll need to have a model set up in your Azure environment. Also, make sure to replace the secrets in the Program.cs file of the client with your own before running it.
services.AddTransient<Kernel>(_ => { IKernelBuilder kernelBuilder = Kernel.CreateBuilder(); kernelBuilder.Services.AddAzureOpenAIChatCompletion("o4-mini", config.Configuration["o4-mini-url"], config.Configuration["o4-mini"], "o4-mini", "o4-mini"); return kernelBuilder.Build(); });

example.server.zip
example.client.zip

[TomasHubelbauer]

Thanks! Much appreciated examples. <3

[vandana2015]

Thanks.

I had got it working on server side using below -

 services.AddMcpServer()
       .WithHttpTransport(options => options.Stateless = true)
       .WithTools<MyControllerOrFileName>();

...
 app.UseEndpoints(endpoints =>
{
    ...
    endpoints.MapMcp("/mcp");  // I have mapped to path /mcp
 });

[vandana2015]

There is https://github.com/modelcontextprotocol/csharp-sdk/blob/main/src/ModelContextProtocol.Core/Client/StreamableHttpClientSessionTransport.cs but it is internal.

I guess what you found @ahmar-husain is the way it is meant to be used, through the SseClientTransport (even though the streamable HTTP transport can be either JSON or SSE, not always SSE...), thanks for sharing this!

I would like to use the JSON version of the streamable HTTP transport. Do we have an option make it use JSON, and not make it SSE?

[ahmar-husain]

There is https://github.com/modelcontextprotocol/csharp-sdk/blob/main/src/ModelContextProtocol.Core/Client/StreamableHttpClientSessionTransport.cs but it is internal.
I guess what you found @ahmar-husain is the way it is meant to be used, through the SseClientTransport (even though the streamable HTTP transport can be either JSON or SSE, not always SSE...), thanks for sharing this!

I would like to use the JSON version of the streamable HTTP transport. Do we have an option make it use JSON, and not make it SSE?

I dont think its possible after looking into the SDK code here (i could be wrong , looked at a very very high level)

[TomasHubelbauer]

I think you can achieve this by setting TransportMode = HttpTransportMode.StreamableHttp on SseClientTransport. It will then not attempt the SSE connection at all (even as a fallback).

[vandana2015]

Thanks @ahmar-husain , @TomasHubelbauer .

My client is in python. Is the JSON or SSE transport governed by client side?

I think Server side would also need to support gthe JSON transport.

Client side code:

client = MultiServerMCPClient(
        {
            "SampleServer": {
                "url": "https://myurl.com/mcp",
                "transport": "streamable_http",
                "headers": {
                    "Authorization": "Bearer <dynamic token>"
                }
            },
        }
    )

[TomasHubelbauer]

The server needs to be configured to support JSON mode (or not). For example in the TypeScript SDK there is enableJsonResponse: true on StreamableHTTPServerTransport. At the same time, the client also has configuration for what it prefers, that's what TransportMode on SseClientTransport in the .NET SDK is for. I have no idea about Python but if the SDK is public, you can search through the source code for similarly named symbols.

[ananthubabu-geodis]

Hey @vandana2015

I use the same code as in your program for the MapMcp() and WithHttpTransport.

But I am getting the error

2025-06-18 18:10:46.631 [info] Starting server vitemcp
2025-06-18 18:10:46.633 [info] Connection state: Starting
2025-06-18 18:10:46.649 [info] Starting server from LocalProcess extension host
2025-06-18 18:10:46.654 [info] Connection state: Running
2025-06-18 18:10:47.778 [info] Discovered 0 tools
2025-06-18 18:10:49.396 [info] Connection state: Error ; will retry with new session ID

VSCode is my mcp-client.

Any idea why? Am I missing something in the server I developed?

[halter73]

I just opened #545 to track supporting the equivalent of the TS SDK's enableJsonResponse: true. That's not currently supported today. Right now the csharp-sdk's client supports both JSON and SSE responses as is required by the spec, but the server only produces SSE responses (which is allowed by spec but maybe not ideal for all use cases).

5. If the input is a JSON-RPC request, the server MUST either
   return Content-Type: text/event-stream, to initiate an SSE stream, or
   Content-Type: application/json, to return one JSON object. The client MUST
   support both these cases.

https://modelcontextprotocol.io/specification/2025-06-18/basic/transports#sending-messages-to-the-server