Basic Chat App Backend

This README provides an overview and setup guide for the backend of a chat application using Express and Socket.IO.

Overview

This chat application backend is built with Node.js, using Express for handling HTTP requests and Socket.IO for real-time bi-directional communication between web clients and the server. The application allows users to join chat rooms, send messages, and see other active users and rooms.

Features

• Real-time chat functionality.
• Users can join and leave chat rooms.
• Broadcast messages to all users in a room.
• Display active users in a room.
• List all active chat rooms.
• Handle user connections and disconnections.

Setup

Prerequisites

• Node.js installed.
• Basic understanding of JavaScript and Node.js.

Installation

1. Clone the repository to your local machine.
2. Navigate to the project directory.
3. Run npm install to install the required dependencies.

Running the Server

1. In the project directory, run npm start.
2. The server will start and listen on the port defined in the environment variable PORT or default to 8000.

Environment Variables

• PORT: The port number on which the server will listen.
• NODE_ENV: The environment ('production' or 'development').

Key Components

• Express Server: Sets up an HTTP server and listens on a specified port.
• Socket.IO: Manages real-time web socket connections.
• UsersState: An object that maintains the current state of users.
• Event Listeners: Socket.IO event listeners for various events like connection, disconnection, message, and room activities.

API Endpoints

This application does not define REST API endpoints, as it primarily operates through web sockets.

Socket Events

• connection: Establishes a socket connection with a client.
• enterRoom: Handles joining a room.
• disconnect: Manages user disconnection.
• message: Sends and receives chat messages.
• activity: Broadcasts user activity in a room.

Utility Functions

• buildMsg: Formats a message object with name, text, and timestamp.
• User management functions: activateUser, userLeavesApp, getUser, getUsersInRoom, getAllActiveRooms.

CORS Configuration

CORS (Cross-Origin Resource Sharing) is configured for both production and development environments.

Conclusion

This backend setup provides a robust foundation for a chat application. It can be integrated with a front-end client to create a full-fledged chat application.

Note

For full functionality, a corresponding front-end application that connects to this server via web sockets is required.