This episode discusses Centrifugo, a powerful and scalable real-time messaging server designed to handle millions of persistent, always-on connections essential for modern instant online experiences. It explains the concept of real-time messaging as an open phone line compared to traditional request-response cycles, highlighting its use in collaborative tools, live updates, and generative AI streaming. The core mechanism is the Publish-Subscribe (PubSub) pattern, where Centrifugo acts as a user-facing PubSub server, efficiently delivering messages from a backend publisher to subscribed users. The server addresses the significant engineering challenge of maintaining millions of concurrent connections by supporting multiple transport protocols like WebSockets, SSE, and gRPC. Centrifugo was created to overcome WebSocket scalability issues and offers an open-source, self-hosted alternative to expensive third-party services, allowing developers to control their infrastructure. Written in Go for high concurrency, it boasts a language-agnostic integration model, allowing it to be easily added as a separate service to applications built in any language. The document emphasizes Centrifugo’s impressive performance metrics, including handling 1 million concurrent WebSocket connections and delivering 30 million messages per minute on modest hardware, and its ability to scale horizontally by integrating with message brokers like Redis and NATS. Advanced features such as hot message history, automatic message recovery, delta compression for bandwidth saving, and online presence information are detailed, showcasing its maturity and real-world problem-solving capabilities. Used by major companies like VK and Grafana, Centrifugo’s reliability is well-established. A PRO version offers enterprise-grade features like analytics and tracing. Ultimately, Centrifugo provides a robust solution for adding real-time features to any application, and with the rise of generative AI, such high-throughput message servers are becoming essential infrastructure.
