Building a DEX SDK with Rust and WebSocket

When building trading systems that interact with decentralized exchanges, performance and reliability are non-negotiable. In this post, I'll walk through the key design decisions behind the Lighter DEX Rust SDK.

Why Rust?

Rust gives us three critical advantages for trading systems:

1. Zero-cost abstractions — no GC pauses during critical trading operations
2. Memory safety — no null pointer exceptions crashing your bot at 3 AM
3. Async ecosystem — Tokio provides excellent async I/O for WebSocket connections

Architecture Overview

The SDK is built around a few core concepts:

pub struct LighterClient {
    ws: WebSocketStream<MaybeTlsStream<TcpStream>>,
    orderbook: Arc<RwLock<OrderBook>>,
    // ...
}

Connection Management

We use tokio-tungstenite for WebSocket connections with automatic reconnection logic. The key insight is separating the connection layer from the business logic layer.

Order Book Maintenance

The local order book is maintained as an Arc<RwLock<OrderBook>>, allowing concurrent reads from strategy threads while the WebSocket handler pushes updates.

Lessons Learned

• Always implement exponential backoff for reconnections
• Keep your hot path allocation-free
• Use crossbeam channels for inter-thread communication when tokio::sync adds too much overhead

What's Next

I'm exploring integrating this with on-chain settlement via Foundry for automated testing of the full trade lifecycle.

Check out the source: lighter-sdk on GitHub