WhatsApp System Design

Design of WhatsApp messenger specific scenarios wise.
We'll try to cover the following scenarios:

1. User Registration and Authentication
2. Sending and Receiving Messages
3. Media Sharing
4. Group Chats
5. Notifications
6. Status Updates

Scenario 1: User Registration and Authentication

Requirements:

• Users should be able to register with their phone number.
• Users should receive a verification code via SMS.
• Users should be able to log in securely.

Design:

1. Client Application: The user enters their phone number and receives a verification code.
2. API Gateway: Routes the registration request to the Authentication Service.
3. Authentication Service:
   • Generates a verification code and sends it via SMS using a third-party service (e.g., Twilio).
   • Verifies the code entered by the user.
   • Creates a new user record in the database.

Scenario 2: Sending and Receiving Messages

Requirements:

• Users should be able to send and receive text messages in real-time.

Design:

1. Client Application: The user sends a message.
2. API Gateway: Routes the message to the Messaging Service.
3. Messaging Service:
   • Uses WebSocket connections to establish real-time communication.
   • Stores the message in a database (e.g., MongoDB).
   • Delivers the message to the recipient's device.

Scenario 3: Media Sharing

Requirements:

• Users should be able to share images, videos, and audio messages.

Design:

1. Client Application: The user selects a media file to share.
2. API Gateway: Routes the media upload request to the Media Service.
3. Media Service:
   • Uploads the media file to a storage service (e.g., AWS S3).
   • Generates a URL for the media file.
   • Stores the URL in the database along with the message metadata.
   • Delivers the media URL to the recipient's device.

Scenario 4: Group Chats

Requirements:

• Users should be able to create and participate in group chats.
• Messages should be delivered to all group members.

Design:

1. Client Application: The user creates a group and adds members.
2. API Gateway: Routes the group creation request to the Group Management Service.
3. Group Management Service:
   • Creates a new group record in the database.
   • Manages group membership and permissions.
4. Messaging Service:
   • Handles the delivery of messages to all group members.
   • Uses WebSocket connections for real-time communication.

Scenario 5: Notifications

Requirements:

• Users should receive notifications for new messages and updates.

Design:

1. Client Application: Registers for push notifications.
2. API Gateway: Routes notification requests to the Notification Service.
3. Notification Service:
   • Uses a push notification service (e.g., Firebase Cloud Messaging) to send notifications to users' devices.
   • Manages notification preferences and delivery.

Scenario 6: Status Updates

Requirements:

• Users should be able to post and view status updates.

Design:

1. Client Application: The user posts a status update.
2. API Gateway: Routes the status update request to the Status Service.
3. Status Service:
   • Stores the status update in the database.
   • Retrieves status updates for display to other users.

By breaking down the design into specific scenarios, we can ensure that each aspect of the WhatsApp messenger is thoroughly covered and designed to meet both functional and non-functional requirements.