How do you efficiently serve the latest personalized movie recommendations to millions of Netflix members, as soon as they are ready?

Netflix recently rolled out Zuul Push - a massively scalable push notification service that handles millions of "always-on" persistent connections from all those Netflix apps running out there. It proactively pushes new data - like personalized movie recommendations - from cloud to devices instead of devices having to poll the server periodically. This has helped reduce data delivery latency and cloud footprint by eliminating wasteful polling requests. It also opens up a whole new set of interesting possibilities like initiating on-demand telemetry of detailed debug data from misbehaving devices in the field.

Zuul push is a high performance async service based on Netty. It supports WebSocket and SSE protocols for push notifications. It handles more than 5.5 million connected clients at peak today and is rapidly growing. We will cover the design of the Zuul Push server and its globally replicated client registry that makes it possible for Netflix to scale to millions of concurrent persistent connections and deliver push notifications globally across the AWS regions.  We will also review the design details of the backend message routing infrastructure that lets any Netflix microservice push notifications to any connected client.

Key takeaways include:

• How push messaging can be used to add new capabilities to your existing application.
• How to scale to large number of persistent connections using Netty and async I/O.
• Differences between operating this type of service versus traditional request/response style stateless REST services.

Join Karen Casella of Netflix as she explores architectural issues with a panel of experts from some of the world's largest architectures.