Real-Time Without The Complexity: Fanout for Edge WebSockets & Pub/Sub

Real-time communication is the instantaneous data transfer between systems and users, bypassing the delays of traditional request-response cycles. Fastly enables this by moving connection management to the network edge, closer to the end-user. By maintaining persistent connections at the edge, Fastly’s push architecture eliminates the need for constant client polling, significantly reducing origin overhead and ensuring updates reach users with sub-millisecond latency.

Fastly supports WebSockets and other real-time protocols through two primary solutions: WebSockets Pass-Through and Fastly Fanout. WebSockets Pass-Through allows WebSocket connections to pass directly through the Fastly edge to a customer’s origin. The connection model is 1:1, bi-directional between the client and the origin. Fanout is an event-driven publish/subscribe (pub/sub) message broker integrated into the Fastly platform. The connection model is 1:many with Fastly managing all connection state at the edge. Fanout can translate between protocols at the edge converting stateful WebSocket, SSE, or Long-polling connections into stateless HTTP requests that an origin already understands.

Yes. Fastly functions as a distributed message broker by leveraging a pub/sub (publish/subscribe) architecture at the edge. Developers can publish a single update and Fastly automatically fans that message out to all authorized subscribers instantly. This offloads the intensive work of message distribution from customers servers to our global network, providing a massive boost in concurrency limits and reliability.

Pub/Sub (Publish/Subscribe) is critical because it decouples the message sender from the receiver, allowing for a highly efficient, event-driven architecture. Instead of your server tracking every individual user connection, it simply sends one publish event to the edge. This reduces egress costs and prevents customer infrastructure from getting overloaded during high-traffic events.

Fastly supports MQTT (Message Queuing Telemetry Transport) architectures by efficiently routing messages and maintaining persistent connections for IoT messaging. By leveraging Fastly’s edge network, developers can create, broker, and scale MQTT pub/sub messaging, connecting IoT devices to cloud services with low latency and high concurrency.

Yes. Fastly is well suited for multi-user chat, live collaboration tools, and shared experiences that require constant updates. Using WebSockets and Fanout, messages can be delivered instantly. The platform ensures that as your user base scales from hundreds to millions, the real-time synchronization of your app remains consistent and performant.

A push architecture is significantly more efficient than HTTP polling because it only sends data when an event actually occurs. Polling can create empty requests that waste CPU cycles and increase billing costs at the origin. By switching to a push model via Fanout, you reduce unnecessary network traffic, lower your infrastructure spend, and provide a better end-user experience.

Fastly’s edge network is built to handle large volumes of concurrent connections. Whether you are managing WebSockets, MQTT, or pub/sub messaging, the platform automatically distributes traffic across its infrastructure. This allows your real-time communication systems to scale without requiring manual intervention or complex capacity planning.