📌 Real-Time Stock Price WebSocket API

🚀 Overview

This project provides a real-time stock price streaming service using WebSockets. Clients can connect to a WebSocket URL and receive live price updates for subscribed stock symbols. The data is fetched from Redis, ensuring fast and efficient real-time updates.

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📂 Folder Structure

📦 Real-Time Data Streaming
 ┣ 📜 server.js         # Main WebSocket server
 ┣ 📜 .env              # Environment variables
 ┣ 📜 package.json      # Node.js dependencies
 ┣ 📜 README.md         # Documentation

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🛠️ Installation

1️⃣ Clone Repository

git clone https://github.com/your-repo/realtime-stock-websocket.git
cd realtime-stock-websocket

2️⃣ Install Dependencies

npm install

3️⃣ Set Up Environment Variables

Create a .env file and configure your database:

PORT=5000
REDIS_HOST=127.0.0.1
REDIS_PORT=6379

4️⃣ Start Redis Server (If not running)

redis-server

5️⃣ Run the WebSocket Server

node server.js

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🌐 WebSocket API Usage

🔹 WebSocket Connection URL

wss://yourserver.com/live-price

🔹 Subscribe to a Stock Symbol

Clients can subscribe to a stock symbol to receive real-time price updates.

📌 Example Client Code

const socket = new WebSocket("wss://yourserver.com/live-price");

socket.onopen = function () {
  console.log("Connected to WebSocket server");
  socket.send(JSON.stringify({ action: "subscribe", symbol: "AAPL" }));
};

socket.onmessage = function (event) {
  const data = JSON.parse(event.data);
  console.log("Live Price Update:", data);
};

🔹 Server Response Format

{
  "symbol": "AAPL",
  "price": 189.45,
  "timestamp": 1712331900000
}

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🔧 Server Implementation

The server listens for WebSocket connections and fetches live price updates from Redis.

📌 WebSocket Server Code (server.js)

const express = require("express");
const http = require("http");
const socketIo = require("socket.io");
const { createClient } = require("redis");

require("dotenv").config();
const app = express();
const server = http.createServer(app);
const io = socketIo(server, { cors: { origin: "*" } });

const redisClient = createClient({
  url: `redis://${process.env.REDIS_HOST}:${process.env.REDIS_PORT}`
});
redisClient.connect().then(() => console.log("Redis Connected")).catch(console.error);

io.on("connection", (socket) => {
  console.log("Client connected:", socket.id);

  socket.on("subscribe", async (symbol) => {
    console.log(`Client subscribed to ${symbol}`);
    const stockData = await redisClient.get(`stock:${symbol}`);
    if (stockData) {
      socket.emit("stockUpdate", JSON.parse(stockData));
    }
    redisClient.subscribe(`stock:${symbol}`, (message) => {
      socket.emit("stockUpdate", JSON.parse(message));
    });
  });

  socket.on("disconnect", () => {
    console.log("Client disconnected:", socket.id);
  });
});

server.listen(5000, () => console.log("Server running on port 5000"));

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📊 Sending Price Updates

Use this function to update stock prices in real-time.

async function sendPriceUpdate(symbol, price) {
  const stockData = { symbol, price, timestamp: Date.now() };
  await redisClient.set(`stock:${symbol}`, JSON.stringify(stockData));
  await redisClient.publish(`stock:${symbol}`, JSON.stringify(stockData));
}

sendPriceUpdate("AAPL", 189.45); // Example Update

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🛡️ Authentication (Optional)

For secure connections, implement JWT-based authentication.

socket.on("authenticate", (token) => {
  const user = verifyToken(token);
  if (!user) return socket.disconnect();
  console.log("Authenticated User:", user.id);
});

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🚀 Advanced Features (Future Scope)

✅ Multi-symbol subscription (Subscribe to multiple stocks in one request)
✅ Kafka Integration (For handling large-scale real-time data)
✅ Historical data retrieval (Fetch past stock price movements)

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🎯 Conclusion

This WebSocket API provides a fast and efficient way to deliver live stock prices using Redis. Clients can connect, subscribe to stock symbols, and receive instant price updates. 🚀