System design — Notification system | part 1

Design a scalable and high-availability Notification System

Photo by Jamie Street on Unsplash

Designing a scalable and high-availability Notification System involves addressing various aspects such as asynchronous processing, queuing, scalability, handling retries, user preferences, and rate limiting. Below is an enterprise-level, in-depth design.

1. Functional Requirements

• Notification Types: Support for multiple notification types, including email, SMS, push notifications, and in-app notifications.
• User Preferences: Ability for users to manage their notification preferences (e.g., channels, frequency, time).
• Scheduling and Prioritization: Notifications can be scheduled for a future time and prioritized based on importance.
• Template Management: Support for dynamic templates that can be personalized based on user data.
• Multi-Tenancy: The system should support multiple clients or tenants, isolating data and preferences.
• Batch Processing: Ability to send notifications in bulk, such as for marketing campaigns.
• Retry Mechanism: Automated retries for failed notifications with a configurable retry policy.
• Analytics and Reporting: Track the status of sent notifications (delivered, opened, clicked) and generate reports.

2. Non-Functional Requirements

• Scalability: System should scale horizontally to handle increasing loads, such as millions of notifications per minute.
• High Availability: Ensure 99.99% uptime with no single point of failure.
• Low Latency: Notifications should be sent with minimal delay, especially for high-priority messages.
• Fault Tolerance: System should be resilient to failures in any component and recover gracefully.
• Data Security: Encrypt sensitive data at rest and in transit, ensure GDPR and other compliance.
• Rate Limiting: Implement rate limits per user, per tenant, and globally to prevent abuse.

3. Traffic, Storage, and Network Estimations