HTTP Transport for servers

[Cclleemm]

I'm trying to build a very simple MCP Server base on HTTP SSE protocol (not STDIO).
This feature is implemented or not ? The MCP doesn't seem to be connected.

import Foundation
import Logging

// Configure Logger
LoggingSystem.bootstrap { label in
    var handler = StreamLogHandler.standardOutput(label: label)
    handler.logLevel = .trace
    return handler
}

// Create logger
let logger = Logger(label: "com.example.mcp")


let server = Server(
    name: "Swift Version Server",
    version: "1.0.0",
    capabilities: .init(tools: .init(listChanged: false))
)

let transport = HTTPClientTransport(
    endpoint: URL(string: "http://localhost:8080")!,
    logger:logger
)
try await server.start(transport: transport)


let tool = Tool(name: "swift_version",
                description: "Returns the current Swift version",
                inputSchema: .object([
                    "type": .string("object")
                ]))

await server.withMethodHandler(ListTools.self) { params in
    ListTools.Result(tools: [tool])
}

await server.withMethodHandler(CallTool.self) { params in
    guard params.name == tool.name else {
        throw MCPError.invalidParams("Wrong tool name: \(params.name)")
    }
    return CallTool.Result(content: [.text(swiftVersion() ?? "No version")])
}

func swiftVersion() -> String? {
    let process = Process()
    process.executableURL = URL(fileURLWithPath: "/usr/bin/env")
    process.arguments = ["swift", "--version"]

    let outputPipe = Pipe()
    process.standardOutput = outputPipe

    do {
        try process.run()
        process.waitUntilExit()

        let data = outputPipe.fileHandleForReading.readDataToEndOfFile()
        return String(data: data, encoding: .utf8)
    } catch {
        return "Error running swift-version: \(error)"
    }
}

await server.waitUntilCompleted()

[sebsto]

Hello Clement,

There is no MCPHTTPServerTransport to implement a server in this library.
You need to create your own HTTP endpoint, using Vapor or Hummingbird, your own custom transport for it and bind the pieces together.

@stallent has a reasonably working implementation in his fork's branch.
Look at the thread here
#110

Based on his work, I created a minimal HTTP server with Hummingbird. I use it for request / responses. I haven't try streamable events yet. You can look at the code, but it's a heavy work in progress.
https://github.com/sebsto/agentkit (the README is not updated, look at the Example directory instead)