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Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

polling

Asking a server again and again whether anything has changed.

Polling repeats a request on a timer to discover changes, trading latency (up to one interval) against wasted requests and battery.

Examples

  • A dashboard polling every 30 s makes 120 requests an hour, and about 97% of them answer "nothing new".

  • With polling, a valve change shows up on average 15 s later and at worst 30 s later.

See also

WebSocket HTTP latency
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