Real-time Chat API

A scalable, production-ready real-time messaging backend built with Socket.IO, Redis, and PostgreSQL.
Supports multi-user chat rooms, instant message broadcasting, and high-performance caching.

Problem Statement

Most chat apps in portfolios are using polling, no auth, no persistence, and break the moment two server instances run. This project builds the real thing: a horizontally scalable, authenticated, real-time messaging API that works across multiple server instances using Redis as the message bus. It's a production-ready backend for a chat application.

This project solves the following problems:

• Delayed message delivery
• High database load
• Poor scalability in chat apps

Features

• User Authentication: Secure user registration and login using JWT and bcrypt.
• Room Management: Create, join, and list chat rooms.
• Real-time Messaging: Send and receive messages in real-time using Socket.io.
• Presence Tracking: See which users are online and in which rooms.
• Message History: Paginated message history for chat rooms.
• Scalability: Utilizes Redis for caching and pub/sub to enable horizontal scaling.
• Database: PostgreSQL with Prisma for type-safe database access.
• Graceful Shutdown: Ensures clean shutdown of server and database connections.

Tech Stack

• Backend: Node.js, Express.js
• Real-time Communication: Socket.io
• Database: PostgreSQL (via Prisma ORM)
• Caching & Pub/Sub: Redis
• Language: TypeScript
• Authentication: JWT (JSON Web Tokens), bcrypt
• Deployment: Supabase (Postgres), Upstash (redis), Render (application host)

Architecture Overview

The application is designed to be scalable and maintainable.

• Express.js: Handles HTTP requests for authentication, room management, and message history.
• Socket.io: Manages persistent WebSocket connections for real-time communication.
• Redis:
  • Caching: Caches recent messages to reduce database load.
  • Pub/Sub: Broadcasts messages across multiple server instances at a time.
• PostgreSQL: The primary data store for users, rooms, and messages.
• Prisma ORM: Provides a type-safe API for database operations.

API Endpoints

All endpoints are prefixed with /.

Auth

• POST /auth/register: Register a new user.
• POST /auth/login: Log in a user.

Rooms

• GET /rooms: Get a list of rooms the user is a member of.
• POST /rooms: Create a new room.
• GET /rooms/:id/messages: Get paginated message history for a room.

WebSocket Events

Client to Server

• message:send: Send a message to a room.
• room:join: Join a room.
• room:leave: Leave a room.
• presence:update: Update the user's presence status.

Server to Client

• message:receive: Receive a new message.
• room:user-joined: A user has joined the room.
• room:user-left: A user has left the room.
• presence:updated: A user's presence has been updated.
• error: If an error has occurred.

Database Schema

The database schema is defined in prisma/schema.prisma and includes the following models:

• User: Stores user information.
• Room: Stores information about chat rooms.
• Message: Stores individual chat messages.
• RoomMember: Manages the relationship between users and rooms.
• ReadReceipt: Tracks when a user has read a message.

Getting Started

Prerequisites

• Node.js (v20 or higher)
• npm

Installation

1. Clone the repository:

   git clone https://github.com/your-username/realtime-chat-api.git
   cd realtime-chat-api

2. Install dependencies:

   npm install

3. Set up environment variables by copying .env.example to .env and fill with you original values:

   cp .env.example .env

4. Running the migrations

   npx prisma generate

5. Testing (NOTE: Replace the urls with the actual ones)

   ts-node src/test-multiuser.ts

Running the App

• Development:

  npm run dev
  npx prisma migrate dev

• Production:

  npm run build
  npm run start
  npx prisma migrate deploy

Environment Variables

The following environment variables are required:

• DATABASE_URL: The connection string for the PostgreSQL database.
• REDIS_URL: The connection string for the Redis instance.
• PORT: The port for the server to run on.
• JWT_SECRET: A secret key for signing JWTs.
• CLIENT_URL: The URL of the client application for CORS.
• MAX_CACHE_MESSAGES: The maximum number of messages to cache in Redis.
• TTL_SECONDS: The time-to-live for cached messages in Redis.

Contributing

Contributions are Open! Feel free to submit a pull request or to contact me.