README.md

🛒 Order Module

Overview

The Order Module is responsible for handling order creation, cancellation, and execution within the trading system. It supports LIMIT and MARKET orders and ensures efficient order matching using Redis Sorted Sets.

Features

• Order Types: Supports both LIMIT and MARKET orders.
• Order Management: Create, cancel, update, and execute orders.
• Order Book: Uses Redis Sorted Sets for efficient price-based sorting.
• Partial Fills: Ensures trades are partially filled if liquidity is insufficient.
• WebSocket Integration: Emits real-time updates on order events.

Order Types

🔹 LIMIT Order

• Placed at a specific price.
• Stored in the order book until matched.
• Sorted descending for bids (BUY) and ascending for asks (SELL).

🔹 MARKET Order

• Executed immediately at the best available price.
• Matches with existing LIMIT orders.
• Supports partial fills if liquidity is insufficient.

Key Components

📂 Directory Structure

order/
├── controllers/
│   └── OrderSocketController.js  # WebSocket controller for order events
├── dtos/
│   ├── cancelOrderDto.js         # DTO for cancel order validation
│   ├── createOrderDto.js         # DTO for create order validation
│   └── index.js
├── models/
│   ├── Order.js                  # Order model with attributes
│   └── index.js
├── repositories/
│   └── OrderRepository.js        # Redis-based order persistence
├── services/
│   └── OrderService.js           # Order processing & matching logic
├── orderConstants.js             # Constants for order types & trade statuses
├── README.md                     # Documentation for Order Module
├── index.js                      # Module entry point

📌 Order Model (Order.js)

export class Order {
  constructor({ orderId, pair, price, quantity, side, status, orderType }) {
    this.orderId = orderId;
    this.pair = pair;
    this.price = price;
    this.quantity = quantity;
    this.side = side;
    this.status = status; // OPEN, FILLED, CANCELLED
    this.orderType = orderType; // LIMIT, MARKET
  }
}

🔧 Order Service (OrderService.js)

Handles order creation, matching, execution, and cancellation.

✅ Order Processing Logic

• LIMIT Orders → Stored in Redis Sorted Sets until matched.
• MARKET Orders → Matched immediately against the best available limit orders.
• Partial Fills → If liquidity is insufficient, only part of the order executes.

📡 WebSocket Events (OrderSocketController.js)

Event Name	Type	Description
createOrder	Client → Server	Creates a new order.
orderCreated	Server → Client	Broadcasts when an order is created.
cancelOrder	Client → Server	Cancels an existing order.
orderCancelled	Server → Client	Broadcasts when an order is canceled.
fillOrder	Client → Server	Executes an order manually.
orderFilled	Server → Client	Broadcasts when an order is filled.
orderBookUpdate	Server → Client	Notifies subscribers when order book changes.

📜 Example WebSocket Payloads

✅ Creating a LIMIT Order

{
  "pair": "ETH_USD",
  "price": 2500,
  "quantity": 2,
  "side": "BUY",
  "orderType": "LIMIT"
}

✅ Creating a MARKET Order

{
  "pair": "ETH_USD",
  "quantity": 3,
  "side": "SELL",
  "orderType": "MARKET"
}

✅ Server Response: Order Created

{
  "event": "orderCreated",
  "success": true,
  "data": {
    "orderId": "12345-xyz",
    "pair": "ETH_USD",
    "price": 2500,
    "quantity": 2,
    "side": "BUY",
    "status": "OPEN",
    "orderType": "LIMIT"
  }
}

Summary

• High-performance order management with Redis Sorted Sets.
• Efficient real-time updates via WebSocket events.
• Flexible order types supporting both LIMIT and MARKET orders.
• Scalable architecture optimized for trading platforms.

📌 Related Modules:

• Trade Module → Handles trade execution.
• Subscription Module → Real-time order book updates.

🚀 This module ensures seamless order execution and high-frequency trading support!