How does Rails handle large-scale real-time notification systems at global scale?

Rails uses pub-sub systems, WebSockets, and push notification services for scalable real-time notifications.

Real-time notifications require event propagation across distributed systems. Rails uses ActionCable for WebSockets, Redis Pub/Sub for event distribution, and external services like Firebase or APNs for mobile notifications. At scale, notification systems are decoupled into dedicated services to handle fan-out efficiently.