WhatsApp System Design

Overview

This project is an implementation of a WhatsApp-like messaging system using Node.js, PostgreSQL, Kafka, WebSockets, and Firebase/Apple Push Notification Services. It models users, groups, chats, and messages, while handling real-time messaging, group functionalities, and notification services.

The architecture follows a microservices approach, with separate services for handling users, messaging, notifications, and file uploads.

Table of Contents

• Architecture
• System Components
• Database Schema
• Technologies Used
• Installation
• Usage
• License

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Architecture

The system consists of the following components:

1. API Gateway: The entry point for all external requests. It handles user authentication and forwards requests to respective microservices.

2. User Service: Manages user registration, authentication, and user-related data.

3. Chat Service: Manages chats, messages, and groups. It interacts with the WebSocket connection for real-time communication and stores chat history in the database.

4. Notification Service: Responsible for sending push notifications via Firebase Cloud Messaging (FCM) and Apple Push Notification Service (APNS).

5. Media Service: Handles file uploads and serves media content like images, videos, and documents.

6. Kafka: Used for message queueing and asynchronous processing of chat events.

7. WebSocket Connection: For real-time messaging between users.

System Components

1. API Gateway

• Handles: HTTP requests (RESTful).
• Responsibilities:
  • Validates incoming requests.
  • Routes requests to appropriate services.
  • Manages authentication and authorization.

2. User Service

• Handles: User registration, authentication, and profile management.
• Database: Stores user details in PostgreSQL.
• Endpoints:
  • /register: User signup.
  • /login: User authentication.

3. Chat Service

• Handles: Messaging, group chats, and message status (sent, delivered, read).
• Database: Stores chat history in PostgreSQL.
• Kafka: Publishes messages to Kafka for real-time delivery.
• WebSocket: Ensures real-time communication between users.

4. Notification Service

• Handles: Push notifications for new messages.
• Technology: Uses Firebase Cloud Messaging (FCM) and Apple Push Notification Service (APNS).

5. Media Service

• Handles: File uploads (images, documents, etc.).
• Storage: Stores files in an object storage service (like AWS S3 or local storage).

Database Schema

Main Entities

• users: Stores information about users, such as name, phoneNumber.
• groups: Stores group chat details.
• users_groups: A junction table connecting users to groups.
• chats: Stores chat sessions (one-on-one or group chats).
• users_chats: A junction table connecting users to chats.
• messages: Stores messages sent in chats, with delivery and read statuses.

Technologies Used

• Node.js: Backend server and API development.
• Express.js: Web framework for building APIs.
• PostgreSQL: Relational database for storing user, group, chat, and message data.
• Sequelize: ORM for PostgreSQL database interaction.
• Kafka: Message queue for handling real-time messages and events.
• Socket.IO: WebSockets for real-time communication.
• Firebase Cloud Messaging (FCM) and APNS: For sending notifications to mobile devices.
• Object Storage: For storing and serving media files.

Installation

Prerequisites

• Node.js
• PostgreSQL
• Kafka (optional for message queuing)
• Firebase or APNS account for notifications

Steps

1. Clone the repository:

   git clone https://github.com/yourusername/whatsapp-system-design.git
   cd whatsapp-system-design

2. Install dependencies:

   npm install

3. Configure environment variables: Create a .env file in the root directory with the following:

   DATABASE_URL=postgres://username:password@localhost:5432/your_database
   JWT_SECRET=your_jwt_secret
   KAFKA_BROKER=kafka-broker-url
   FCM_SERVER_KEY=your_fcm_key
   APNS_KEY=your_apns_key

4. Run the PostgreSQL migrations:

   npx sequelize-cli db:migrate

5. Start the server:

   npm start

Usage

• Register User:

  • POST /api/register
  • Payload: { "name": "User Name", "phoneNumber": "1234567890" }

• Send a Message:

  • POST /api/messages
  • Payload: { "chatID": "chat-uuid", "content": "Hello World", "type": "text" }

• WebSocket Communication:

  • Clients connect via WebSocket for real-time messaging.
  • URL: ws://your-server-url/ws

License

This project is licensed under the MIT License - see the LICENSE file for details.