Real-Time Chat Application (Server)

This is the server-side of a real-time chat application with file-sharing capabilities. Built using Node.js, Express, Socket.IO, and MongoDB, it allows users to join chat rooms, send/receive real-time messages, and share files using Node.js streams and buffers. User authentication, chat history, and file metadata are stored securely in MongoDB.

Features

Real-time Communication: Users can send and receive messages in real-time using Socket.IO.
File Sharing: Efficient file uploads/downloads with Node.js streams and buffers.
User Authentication: Secure user login and registration using JWT (JSON Web Tokens).
Persistent Chat History: MongoDB stores chat messages, user data, and file metadata for future retrieval.
Scalability: The application is designed for horizontal scaling and optimized for concurrent users.

Technologies Used

Node.js: JavaScript runtime for building server-side logic.
Express: Fast web framework for Node.js.
Socket.IO: Enables real-time, bidirectional communication between server and client.
MongoDB: NoSQL database used for chat storage and user management.
JWT: Secure user authentication using JSON Web Tokens.
Streams & Buffers: Handle large file uploads/downloads without blocking the server.

Project Structure

.
├── .env
├── .env.example
├── .gitignore
├── app.js
├── config
│   ├── db.js
│   └── jwtConfig.js
├── controllers
│   ├── authController.js
│   ├── chatController.js
│   └── chatRoomController.js
├── middleware
│   └── authMiddleware.js
├── models
│   ├── ChatMessage.js
│   ├── ChatRoom.js
│   └── User.js
├── routes
│   ├── authRoutes.js
│   ├── chatRoomRoutes.js
│   ├── chatRoutes.js
│   
├── services
│   └── socketService.js
├── socket.js
├── swagger.js
├── uploads
├── utils
│   ├── logger.js
│   └── responseFormatter.js
├── seeder.js
└── tests
    ├── auth.test.js
    └── chat.test.js

Installation

Prerequisites

Node.js (version 14 or above)
MongoDB (locally or cloud-hosted)
Docker (optional, for containerized deployment)

Step-by-Step Setup

Clone the repository:

git clone https://github.com/jmrashed/chat-backend.git
cd chat-backend

Install dependencies:
```
npm install
```
Create a .env file:

In the root of the project directory, create a .env file with the following content:
```
PORT=3000
MONGODB_URI=mongodb://localhost:27017/realtime-chat-app
JWT_SECRET=your_secret_key
```
Start MongoDB:

Make sure MongoDB is running locally or connect to your cloud MongoDB instance.
```
mongod
```
Run the server:

Start the application with:
```
npm start
```
Access the Application:

Open your browser and navigate to http://localhost:3000.

Running Tests

To execute tests for authentication and chat functionality, use the following command:

npm test

Docker Setup

To run the server in a Docker container:

Build the Docker image:

docker build -t realtime-chat-app-server .

Run the Docker container:

docker run -d -p 3000:3000 realtime-chat-app-server

Access the Application:

Navigate to http://localhost:3000 to use the chat application.

API Documentation

For API documentation, you can explore the endpoints through Postman or Swagger:

Postman Documentation: Postman Collection
Swagger UI: Available locally at /api-docs after starting the server.

Scalability and Optimization

Horizontal Scaling: Cluster the app or use multiple instances behind a load balancer.
Redis: Use Redis to handle session management and WebSocket scaling with Socket.IO.
Database Indexing: Ensure MongoDB collections are indexed for optimal query performance.
Rate Limiting: Implement rate limiting to control API usage and prevent server overload.

Error Handling

The application includes robust error handling for:

Invalid JWT tokens
Database connection errors
File upload/download issues
User authentication failures

Future Improvements

Private Messaging: Implement direct messaging between individual users.
Group Chats: Allow for group chat rooms with multiple participants.
Notifications: Add real-time notifications for new messages or file uploads.
OAuth Integration: Implement social logins via Google, Facebook, etc.
Admin Dashboard: Build a dashboard for managing users, chat rooms, and file uploads.

jmrashed/chat-backend