WhatsApp System Design

System Design of WhatsApp Service

Designing a highly scalable and reliable messaging service like WhatsApp involves understanding and implementing several key components. This article provides a comprehensive overview of the system design of WhatsApp, covering aspects such as architecture, message flow, data storage, user management, security, and scaling strategies.

Overview of WhatsApp

WhatsApp is a widely used instant messaging service that allows users to send text messages, multimedia (images, videos, voice notes), and make voice and video calls. The key requirements for such a service include low latency, high availability, end-to-end encryption, and the ability to handle millions of concurrent users.

High-Level Architecture

The architecture of WhatsApp can be divided into several major components:

• Client Applications: Mobile apps (iOS, Android), desktop clients, and web clients.
• Load Balancers: Distribute incoming requests to various servers to handle load.
• Application Servers: Handle user connections, message routing, and business logic.
• Message Servers: Ensure delivery of messages to the correct recipients.
• Media Servers: Handle storage and retrieval of multimedia content.
• Database Servers: Store user data, message histories, and other persistent information.
• Notification Servers: Send push notifications to users.

Message Flow

1. User A sends a message to User B: The client application on User A’s device sends the message to the WhatsApp server.
2. Load Balancer: The request is first handled by a load balancer which forwards it to an appropriate application server.
3. Application Server: The server authenticates User A, processes the message, and determines the recipient (User B).
4. Message Server: The message is then sent to a message server which queues the message for delivery to User B.
5. User B receives the message: When User B comes online, the message server delivers the message to User B’s…