Web & APIsIntermediate
Long Polling
PronunciationLONG POL-ing
Definition
A technique where the client makes an HTTP request, and the server holds that connection open until new data is available or a timeout occurs.
Where you hear it
In architecture discussions about real-time features, chat applications, or notification systems when WebSockets are not an option.
Examples
The notification service uses long polling to deliver alerts to the browser without opening a permanent socket.
When the server receives a long polling request, it waits for thirty seconds before returning an empty response if no changes occur.
Common mistake
Assuming long polling is identical to WebSockets, forgetting that it still relies on standard HTTP request-response cycles and requires a new request after every message.