🚀 Scalable Real-Time Collaborative Code Submission System

A distributed, real-time code submission and processing system built with Node.js, Redis, WebSockets, and React. This architecture demonstrates horizontal scalability with multiple WebSocket servers synchronized via Redis Pub/Sub.

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📋 Table of Contents

• Architecture Overview
• Key Features
• Tech Stack
• System Architecture
• Prerequisites
• Installation
• Running the Application
• API Documentation
• How It Works
• Project Structure
• Testing
• Configuration
• Future Enhancements

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🏗️ Architecture Overview

This system enables multiple users to submit code for processing while receiving real-time results through WebSocket connections. The architecture supports horizontal scaling with multiple WebSocket servers that communicate through Redis Pub/Sub.

Architecture Diagram

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✨ Key Features

• Real-Time Communication: Instant result delivery via WebSocket connections
• Horizontal Scalability: Multiple WebSocket servers handle concurrent connections
• Distributed Architecture: Redis Pub/Sub synchronizes events across all servers
• Queue-Based Processing: Workers poll from Redis queue for reliable processing
• Multi-User Support: Each user gets isolated, real-time updates
• Load Distribution: Clients automatically distributed across WebSocket servers
• Session Persistence: Tab-specific user sessions with unique IDs

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🛠️ Tech Stack

Backend

• Node.js - Runtime environment
• Express.js - HTTP server framework
• Socket.IO - WebSocket library for real-time communication
• Redis - Message broker (Pub/Sub) and queue storage

Frontend

• React.js - UI framework
• Socket.IO Client - WebSocket client library

Infrastructure

• Redis Server - Message queue and pub/sub broker

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🎯 System Architecture

Components

1. Client (Browser)

   • React-based frontend
   • Establishes WebSocket connection
   • Submits code via REST API
   • Receives real-time results

2. Express Backend (Server.js)

   • REST API endpoint /submit
   • Pushes submissions to Redis queue
   • Validates user input

3. Workers (Worker.js)

   • Poll submissions from Redis queue using BRPOP
   • Process code submissions
   • Publish results to Redis Pub/Sub channel processed

4. WebSocket Servers (Multiple Instances)

   • Handle WebSocket connections on ports 4000, 4001, 4002
   • Subscribe to Redis processed channel
   • Deliver results to specific users via Socket.IO rooms

5. Redis

   • Queue: Stores pending submissions
   • Pub/Sub: Broadcasts processed results to all WebSocket servers

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📦 Prerequisites

• Node.js (v16 or higher)
• npm or yarn
• Redis server running locally or via Docker

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🔧 Installation

1. Clone the Repository