How to Build Resilient WebSocket Clients With Heartbeats, Backoff, and Replay

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WebSocket connections can silently fail while still appearing open, a problem the developer discovered while building an automated futures trading bot that relied on live market data. Standard tutorials cover basic connection setup but rarely address four critical production failures: detecting dead connections, avoiding reconnection stampedes, restoring subscriptions, and recovering missed messages. The author explains that trusting the socket's readyState property is unreliable, since network-layer drops can leave a connection appearing open while no data flows. The recommended fix is an application-level heartbeat that sends a ping at regular intervals and declares the connection dead if no pong is received within a set deadline. The piece notes these challenges apply broadly to any live-feed product, including chat apps, IoT telemetry, dashboards, and collaborative editing tools.

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ProgrammingDEV Community ·

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