TurboMCP Transport

Transport layer implementation for the Model Context Protocol (MCP) with support for multiple transport protocols and connection patterns.

Table of Contents

• Overview
• Key Features
• Architecture
• Transport Protocols
• Security Configuration
• Reliability Features
• Compression Support
• Health Monitoring
• Performance Optimization
• Integration

Overview

turbomcp-transport provides transport layer implementations for the Model Context Protocol. It supports multiple transport protocols including STDIO, HTTP/SSE, WebSocket, TCP, and Unix sockets with features for security, reliability, and concurrent usage.

Key Features

Multi-Protocol Support

MCP Standard Transports (MCP 2025-06-18 Specification):

• STDIO - Standard input/output for subprocess communication
• HTTP/SSE - Streamable HTTP with Server-Sent Events for web integration

MCP-Compliant Custom Extensions:

• WebSocket - Real-time bidirectional communication
• TCP - Direct TCP connections with connection pooling
• Unix Sockets - Inter-process communication on Unix systems

All transports preserve JSON-RPC message format and MCP lifecycle requirements.

Security Features

• TLS 1.3 Support - Modern encryption with rustls
• CORS Protection - Cross-origin resource sharing configuration
• Security Headers - CSP, HSTS, X-Frame-Options, and more
• Rate Limiting - Token bucket algorithm for request rate control
• Authentication - JWT validation and API key support

Reliability Features

• Circuit Breaker Pattern - Prevents cascade failures with automatic recovery
• Exponential Backoff - Retry logic with jitter
• Connection Health Monitoring - Automatic detection of connection issues
• Graceful Degradation - Fallback mechanisms and error recovery
• Resource Management - Memory usage controls with cleanup tasks

Compression Support

• Multiple Algorithms - gzip, brotli, lz4 compression options
• Adaptive Compression - Algorithm selection based on content
• Streaming Support - Low-memory compression for large messages
• Compression Metrics - Performance monitoring capabilities

SharedTransport for Async Concurrency

• Thread-safe transport sharing - Share transports across multiple async tasks
• Clean API surface - Hide Arc/Mutex complexity from public interfaces
• Protocol compliant - Preserves all transport semantics
• Clone support - Easy sharing with simple .clone() operations

Architecture

┌─────────────────────────────────────────────┐
│            TurboMCP Transport               │
├─────────────────────────────────────────────┤
│ MCP Standard Transports (2025-06-18)      │
│ ├── STDIO (subprocess communication)       │
│ └── HTTP/SSE (streamable HTTP)             │
├─────────────────────────────────────────────┤
│ MCP-Compliant Custom Extensions            │
│ ├── WebSocket (bidirectional streaming)   │
│ ├── TCP (network services)                 │
│ └── Unix Sockets (local IPC)               │
├─────────────────────────────────────────────┤
│ Security & Authentication                  │
│ ├── TLS 1.3 encryption                    │
│ ├── JWT token validation                   │
│ ├── CORS and security headers             │
│ ├── Rate limiting                          │
│ └── Certificate management                 │
├─────────────────────────────────────────────┤
│ Reliability & Fault Tolerance             │
│ ├── Circuit breaker pattern               │
│ ├── Exponential backoff retry             │
│ ├── Connection pooling                     │
│ ├── Health monitoring                      │
│ └── Graceful degradation                   │
├─────────────────────────────────────────────┤
│ Performance & Optimization                 │
│ ├── Multi-algorithm compression            │
│ ├── Connection reuse                       │
│ ├── Message batching                       │
│ └── Memory-efficient streaming             │
└─────────────────────────────────────────────┘

Transport Protocols

STDIO Transport

For local process communication:

use turbomcp_transport::stdio::{StdioTransport, ChildProcessConfig};

// Direct process communication
let transport = StdioTransport::new();

// Child process management
let config = ChildProcessConfig::new()
    .command("/usr/bin/python3")
    .args(["-m", "my_mcp_server"])
    .working_directory("/path/to/server")
    .environment_vars([("DEBUG", "true")]);

let child_transport = StdioTransport::with_child_process(config).await?;

MCP 2025-06-18 Streamable HTTP (Client)

For connecting to HTTP-based MCP servers with full SSE support:

use turbomcp_transport::streamable_http_client::{
    StreamableHttpClientConfig, StreamableHttpClientTransport
};
use std::time::Duration;

// MCP 2025-06-18 compliant HTTP client with SSE
let config = StreamableHttpClientConfig {
    base_url: "http://localhost:8080".to_string(),
    endpoint_path: "/mcp".to_string(),
    timeout: Duration::from_secs(30),
    ..Default::default()
};

let mut transport = StreamableHttpClientTransport::new(config);

WebSocket Transport

For real-time communication:

use turbomcp_transport::websocket_bidirectional::{
    WebSocketBidirectionalTransport, WebSocketBidirectionalConfig
};

// Connect to WebSocket server with full MCP 2025-06-18 support
let config = WebSocketBidirectionalConfig {
    url: Some("wss://api.example.com/mcp".to_string()),
    ..Default::default()
};
let transport = WebSocketBidirectionalTransport::new(config).await?;

// Full MCP 2025-06-18 features:
// - Bidirectional request-response correlation
// - Server-initiated elicitation support
// - Automatic reconnection with exponential backoff
// - Keep-alive ping/pong
// - Optional TLS and compression

TCP Transport

For network socket communication:

use turbomcp_transport::tcp::TcpTransportBuilder;
use std::net::SocketAddr;

let bind_addr: SocketAddr = "127.0.0.1:8080".parse()?;

let transport = TcpTransportBuilder::new()
    .bind_addr(bind_addr)
    .keep_alive(true)
    .buffer_size(64 * 1024) // 64KB
    .build();

Unix Socket Transport

For local inter-process communication:

use turbomcp_transport::unix::{UnixTransport, UnixConfig};
use std::path::PathBuf;

let config = UnixConfig {
    socket_path: PathBuf::from("/tmp/mcp.sock"),
    permissions: Some(0o660),
    buffer_size: 8192,
    cleanup_on_disconnect: true,
};

let transport = UnixTransport::new(config);

Security Configuration

Security Validator Setup

use turbomcp_transport::{SecurityConfigBuilder, AuthMethod, RateLimitConfig};
use std::time::Duration;

// Build a security validator with authentication and rate limiting
let validator = SecurityConfigBuilder::new()
    .add_allowed_origin("https://app.example.com".to_string())
    .allow_localhost(true)
    .require_authentication(true)
    .with_auth_method(AuthMethod::ApiKey)
    .add_api_key("your-api-key-here".to_string())
    .with_rate_limit(100, Duration::from_secs(60)) // 100 requests per minute
    .build();

Enhanced Security with Session Management

use turbomcp_transport::EnhancedSecurityConfigBuilder;
use std::time::Duration;

// Build enhanced security with session tracking
let enhanced_security = EnhancedSecurityConfigBuilder::new()
    .add_allowed_origin("https://app.example.com".to_string())
    .require_authentication(true)
    .add_api_key("your-api-key".to_string())
    .with_rate_limit(120, Duration::from_secs(60))
    .with_session_max_lifetime(Duration::from_secs(3600)) // 1 hour max session lifetime
    .with_session_idle_timeout(Duration::from_secs(1800)) // 30 min inactivity timeout
    .with_max_sessions_per_ip(5) // Max 5 sessions per IP address
    .build();

Reliability Features

Circuit Breaker Configuration

use turbomcp_transport::resilience::circuit_breaker::CircuitBreakerConfig;
use std::time::Duration;

// Configure circuit breaker for fault tolerance
let circuit_config = CircuitBreakerConfig {
    failure_threshold: 5,           // Open circuit after 5 failures
    success_threshold: 3,            // Close circuit after 3 successes
    timeout: Duration::from_secs(60), // Wait 60s before trying again
    rolling_window_size: 100,        // Track last 100 operations
    minimum_requests: 10,            // Need 10 requests before opening
};

Retry Configuration

use turbomcp_transport::resilience::retry::RetryConfig;
use std::time::Duration;

// Configure retry behavior with exponential backoff
let retry_config = RetryConfig {
    max_attempts: 3,
    base_delay: Duration::from_millis(100),
    max_delay: Duration::from_secs(10),
    backoff_multiplier: 2.0,
    jitter_factor: 0.1,
    retry_on_connection_error: true,
    retry_on_timeout: true,
    custom_retry_condition: None,
};

Compression Support

Message Compression

use turbomcp_transport::compression::{MessageCompressor, CompressionType};
use serde_json::json;

// Create a compressor with LZ4 compression
let compressor = MessageCompressor::new(CompressionType::Lz4);

// Compress a message
let message = json!({"tool": "add", "args": {"a": 5, "b": 3}});
let compressed = compressor.compress(&message)?;

// Decompress back to JSON
let decompressed = compressor.decompress(&compressed)?;
assert_eq!(message, decompressed);

// Available compression types:
// - CompressionType::None
// - CompressionType::Gzip (with "flate2" feature)
// - CompressionType::Brotli (with "brotli" feature)
// - CompressionType::Lz4 (with "lz4_flex" feature)

Health Monitoring

Health Check Configuration

use turbomcp_transport::resilience::health::{HealthCheckConfig, HealthStatus};
use std::time::Duration;

// Configure health checking
let health_config = HealthCheckConfig {
    interval: Duration::from_secs(30),
    timeout: Duration::from_secs(5),
    failure_threshold: 3,      // Unhealthy after 3 failures
    success_threshold: 2,      // Healthy after 2 successes
    custom_check: None,
};

// Health status can be:
// - HealthStatus::Healthy
// - HealthStatus::Unhealthy
// - HealthStatus::Unknown
// - HealthStatus::Checking

Integration Examples

With TurboMCP Framework

Transport selection is automatic when using the main framework:

use turbomcp::prelude::*;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let server = MyServer::new();
    
    // Transport selected based on environment/configuration
    match std::env::var("TRANSPORT").as_deref() {
        Ok("http") => server.run_http("127.0.0.1:8080").await?,
        Ok("websocket") => server.run_websocket("127.0.0.1:8080").await?,
        Ok("tcp") => server.run_tcp("127.0.0.1:8080").await?,
        Ok("unix") => server.run_unix("/tmp/mcp.sock").await?,
        _ => server.run_stdio().await?, // Default
    }
    
    Ok(())
}

Custom Transport Implementation

use turbomcp_transport::{Transport, TransportMessage, TransportConfig};
use async_trait::async_trait;

struct CustomTransport {
    config: TransportConfig,
    // ... custom fields
}

#[async_trait]
impl Transport for CustomTransport {
    async fn send(&self, message: TransportMessage) -> Result<(), TransportError> {
        // Custom send implementation
        Ok(())
    }
    
    async fn receive(&self) -> Result<TransportMessage, TransportError> {
        // Custom receive implementation
        todo!()
    }
    
    async fn close(&self) -> Result<(), TransportError> {
        // Cleanup implementation
        Ok(())
    }
}

Feature Flags

SharedTransport for Async Concurrency

TurboMCP introduces SharedTransport - a thread-safe wrapper that eliminates Arc/Mutex complexity while preserving full transport functionality:

Basic SharedTransport Usage

use turbomcp_transport::{StdioTransport, SharedTransport};

// Create and wrap any transport for sharing
let transport = StdioTransport::new();
let shared = SharedTransport::new(transport);

// Connect once
shared.connect().await?;

// Clone for concurrent usage across tasks
let shared1 = shared.clone();
let shared2 = shared.clone();

// Both tasks can use the transport concurrently
let handle1 = tokio::spawn(async move {
    shared1.send(message1).await
});

let handle2 = tokio::spawn(async move {
    shared2.receive().await
});

let (send_result, message) = tokio::join!(handle1, handle2);

Concurrent Patterns

use turbomcp_transport::SharedTransport;
use std::sync::Arc;
use tokio::sync::Semaphore;

// Rate-limited concurrent transport operations
let shared_transport = SharedTransport::new(transport);
let semaphore = Arc::new(Semaphore::new(10)); // Max 10 concurrent operations

let tasks = (0..50).map(|i| {
    let transport = shared_transport.clone();
    let semaphore = semaphore.clone();

    tokio::spawn(async move {
        let _permit = semaphore.acquire().await.unwrap();

        let message = create_message(i);
        transport.send(message).await?;
        transport.receive().await
    })
}).collect::<Vec<_>>();

// Wait for all operations to complete
let results = futures::future::join_all(tasks).await;

Integration with Multiple Clients

use turbomcp_transport::SharedTransport;
use turbomcp_client::Client;

// Share a single transport across multiple clients
let transport = TcpTransport::connect("127.0.0.1:8080").await?;
let shared_transport = SharedTransport::new(transport);

// Create multiple clients sharing the same transport
let client1 = Client::new(shared_transport.clone());
let client2 = Client::new(shared_transport.clone());
let client3 = Client::new(shared_transport.clone());

// Initialize all clients concurrently
let (result1, result2, result3) = tokio::try_join!(
    client1.initialize(),
    client2.initialize(),
    client3.initialize()
)?;

// All clients can now operate independently
tokio::spawn(async move {
    loop {
        let tools = client1.list_tools().await?;
        // Process tools...
        tokio::time::sleep(Duration::from_secs(30)).await;
    }
});

tokio::spawn(async move {
    loop {
        let resources = client2.list_resources().await?;
        // Process resources...
        tokio::time::sleep(Duration::from_secs(45)).await;
    }
});

Benefits

• Clean APIs: No exposed Arc/Mutex types in transport interfaces
• Easy Sharing: Simple .clone() for concurrent access
• Thread Safety: Built-in synchronization for async operations
• Zero Overhead: Same performance as direct transport usage
• Protocol Compliant: Preserves all transport semantics exactly
• Universal Compatibility: Works with all transport types (STDIO, HTTP, WebSocket, TCP, Unix)

Performance Characteristics

Typical Performance Metrics

These metrics are indicative and will vary based on hardware, message size, and system load.

Optimization Features

• Connection Pooling - Reuse connections for better performance
• Message Batching - Combine small messages for efficiency
• Smart Compression - Adaptive compression based on content
• Zero-Copy - Minimize memory allocations where possible

Development

Building

# Build with all features
cargo build --all-features

# Build specific transport
cargo build --features http,websocket

# Build without TLS (for testing)
cargo build --no-default-features --features stdio,tcp

Testing

# Run transport tests
cargo test

# Test with TLS
cargo test --features tls

# Run integration tests
cargo test --test integration

# Test circuit breaker functionality
cargo test circuit_breaker

Security Documentation

For comprehensive security information, see:

• Security Features Guide - Detailed security documentation including TLS configuration and authentication setup

Related Crates

• turbomcp - Main framework (uses this crate)
• turbomcp-protocol - Protocol implementation and core utilities
• turbomcp-server - Server framework

External Resources

• Axum Framework - HTTP framework used for HTTP transport
• tokio-tungstenite - WebSocket implementation
• rustls - TLS implementation

License

Licensed under the MIT License.

Part of the TurboMCP Rust SDK for the Model Context Protocol.