⚙️ Vi-SlideS Backend Documentation

A simplified overview of the Node.js backend architecture and features.

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🧱 Backend Structure

src/
├── server.ts          # Express setup
├── socketServer.ts    # Real-time (Socket.IO)
├── config/db.ts       # MongoDB connection
├── controllers/       # Logic (auth, session, AI, QR)
├── models/            # MongoDB schemas
├── routes/            # API endpoints
├── middleware/        # Auth (JWT)
└── services/          # AI integration

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🚀 Core Responsibilities

• Authentication (JWT + Google)
• Session management (create/join/end)
• Real-time Q&A (Socket.IO)
• AI-powered answers
• QR-based question submission

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🔌 Server (server.ts)

• Initializes Express app
• Connects to MongoDB
• Registers routes
• Starts server

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🔄 Real-time System (socketServer.ts)

Handles live classroom interaction.

Main flow:

• User joins session → added to room
• Questions sent → broadcast to all
• Answers (manual/AI) → updated live
• Session end → all users notified

Key events:

• new-question
• new-answer
• ai-answer
• update-students
• session-ended

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🗄️ Database Models

User

• name, email, password
• role (student / teacher)

Session

• code, name, status
• students list
• questions list

Question

• question text
• answer / AI answer
• source (session / QR)

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🎮 Controllers

Auth

• Register / Login / Google login
• Returns JWT token

Session

• Create session (teacher only)
• Fetch session
• End session

AI

• Teacher triggers AI answer
• Response stored + broadcast

QR

• Public question submission
• No login required

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🤖 AI Service

• Uses Groq API
• Generates short teaching answers
• Response saved and sent in real-time

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🔐 Authentication

• JWT-based
• Protected routes use middleware
• Token stored on client

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🌐 API Routes

Auth

• /register
• /login
• /profile

Session

• /create-session
• /session/:code
• /session/:code/end

AI

• /ask-ai

QR

• /ask/:code

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⚡ System Flow

Teacher creates session
→ Students join (code / QR)
→ Questions submitted
→ Teacher answers or uses AI
→ Updates sent in real-time
→ Session ends → summary generated

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📦 Data Handling

• MongoDB → persistent storage
• In-memory cache → active sessions
• Socket.IO → real-time updates

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🔒 Security

• Password hashing (bcrypt)
• JWT authentication
• Basic validation

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🧠 Summary

Backend is designed to be:

• real-time (Socket.IO)
• scalable (MongoDB)
• secure (JWT)
• extensible (AI + QR features)