Solana DEX Routing Backend

A backend system for a Solana DEX routing and order execution engine (MOCK), built with Node.js, Fastify, BullMQ, Redis, and PostgreSQL.

Features

• Market Order Execution: Supports immediate execution with best-price routing.
• Mock DEX Router: Simulates quotes from Raydium and Meteora with price variations and delays.
• Queue System: Uses BullMQ for handling orders with a max concurrency of 10 and rate limiting.
• WebSocket Streaming: Real-time order status updates (pending, routing, building, submitted, confirmed, failed).
• Data Persistence: Stores all orders and execution logs in PostgreSQL.

Tech Stack

• Runtime: Node.js + TypeScript
• Server: Fastify + @fastify/websocket
• Queue: BullMQ + Redis
• Database: PostgreSQL + Prisma ORM
• Validation: Zod
• Testing: Jest

Setup

1. Prerequisites:

   • Node.js (v16+)
   • Docker & Docker Compose

2. Installation:

   npm install
   

3. Environment Variables: Create a .env file:

   PORT=3000
   REDIS_HOST=localhost
   REDIS_PORT=6379
   DATABASE_URL="postgresql://user:password@localhost:5432/dex_routing?schema=public"

4. Start Infrastructure:

   docker-compose up -d
   

5. Run Migrations:

   npx prisma migrate dev --name init
   

6. Start Server:

   npm run dev
   

API Usage

Execute Order

Endpoint: POST http://localhost:3000/api/orders/execute

Body:

{
  "inputToken": "SOL",
  "outputToken": "USDC",
  "amount": 10
}

Response:

{
  "success": true,
  "orderId": "uiqueorderId-string",
  "message": "Order queued. Connect to WebSocket for updates."
}

WebSocket Stream

URL: ws://localhost:3000/ws/orders/<orderId>

Messages:

{ "status": "routing" }
{ "status": "building" }
{ "status": "submitted" }
{ "status": "confirmed", "txHash": "...", "price": 102.5, "dex": "Raydium" }

Architecture

1. API Layer: Receives requests, validates input, creates DB record, and pushes to Queue.
2. Queue Layer: BullMQ handles async processing, retries, and concurrency control.
3. Worker Layer: Processes orders, calls the Router, and updates DB/WebSocket.
4. Router Layer: Simulates DEX interactions.
5. WebSocket Layer: Streams updates to the client.