GraphQL Subscriptions Are Stateful; We Made Them Stateless

Session description

GraphQL Subscriptions over WebSockets is an extremely popular way to notify the caller that something happened on the back end. While a high level of Quality of Service is possible in other protocols such as STOMP or MQTT, there is no actual guarantee of delivery with GraphQL Subscriptions: any acknowledgment mechanism should be built in userland. WebSockets can be interrupted at any time with both graceful and ungraceful disconnections, and the lack of acknowledgment in the subscription protocol affects reliability, making GraphQL Subscription over WebSocket connections susceptible to disconnections, as any protocol failures will result in messages being lost. In other words, Subscriptions are stateful. In this talk, we will investigate a mitigation technique to make them resumable so that the connection can be destroyed and recreated without any message loss.