mcpkit-transport

Transport abstractions for the Model Context Protocol (MCP).

This crate provides transport layer implementations that handle the low-level details of sending and receiving JSON-RPC messages between MCP clients and servers.

Overview

The transport layer is responsible for:

Serializing and deserializing JSON-RPC messages
Managing connection lifecycle
Providing different transport implementations

Available Transports

Transport	Description
`StdioTransport`	Standard I/O for subprocess communication
`SpawnedTransport`	Spawn and connect to a subprocess
`MemoryTransport`	In-memory transport for testing
`HttpTransport`	HTTP/SSE transport (with `http` feature)
`WebSocketTransport`	WebSocket transport (with `websocket` feature)
`UnixTransport`	Unix domain sockets (Unix only)

Usage

use mcpkit_transport::{Transport, SpawnedTransport};

#[tokio::main]
async fn main() -> Result<(), mcpkit_transport::TransportError> {
    // Spawn an MCP server as a subprocess
    let transport = SpawnedTransport::spawn("my-mcp-server", &[] as &[&str]).await?;

    // Receive messages
    while let Some(msg) = transport.recv().await? {
        // Handle the message
    }

    transport.close().await?;
    Ok(())
}

Feature Flags

Feature	Description
`tokio-runtime` (default)	Use Tokio for async I/O
`smol-runtime`	Use smol for async I/O
`http`	Enable HTTP/SSE transport
`websocket`	Enable WebSocket transport

Middleware

The transport layer supports middleware for:

Logging and telemetry
Message transformation
Connection pooling

Part of mcpkit

This crate is part of the mcpkit SDK. For most use cases, depend on mcpkit directly rather than this crate.

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

mcpkit-transport 0.5.0