Abstracting the MCP Servers from their transport

[raffaeler]

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• I have verified that this discussion would not be more appropriate as an issue in a specific repository
• I have searched existing discussions to avoid duplicates

Discussion Topic

The stdio and HTTP transport are well abstracted in the library, but the local mcp servers are treated as a special case.
In the old times we had COM and Remoting which provided the "transparency" concept as opposed to the SOA architecture.

What I am asking is the ability to activate an MCP server regardless it is in-process or over stdio/HTTP. The protocol decision should be just a matter of configuration settings.

I already implemented the required code on my own, which consists on:

• A class holding the two Pipes needed to communicate with the inproc MCP server
• A proxy class that, based on the configuration, creates the appropriate transport to communicate with the MCP server and creates the corresponding MCP Client instance. For inproc MCP servers, I decided to create a single MCP Client.
• Three JSON converters to create the transports (stdio, HTTP and inproc) based on the JSON de-facto standard configuration used by VSCode, ClaudeAI and others. The inproc converter is optional and used only when the user want to manually load an external dll containing MCP servers.

Beyond the choices I made for my own scenarios, I believe that supporting the transparency concept could be really helpful for application developers.

Any thoughts?

[mikekistler]

If you want an MCP server that can use either transport, this only requires a little bit of extra code in the Program.cs. Here's an example from a project I recently built:

if (args.Contains("--stdio"))
{
    var builder = Host.CreateApplicationBuilder(args);
    builder.Logging.AddConsole(options =>
    {
        options.LogToStandardErrorThreshold = LogLevel.Trace;
    });
    RegisterHttpClient(builder.Services);
    ConfigureMcp(builder.Services.AddMcpServer(ConfigureOptions).WithStdioServerTransport());
    await builder.Build().RunAsync();
}
else
{
    var builder = WebApplication.CreateBuilder(args);
    RegisterHttpClient(builder.Services);
    ConfigureMcp(builder.Services.AddMcpServer(ConfigureOptions).WithHttpTransport());
    var app = builder.Build();
    app.MapMcp();
    app.Run();
}