Webhook.

also: webhooks · web hook

An HTTP callback: when an event happens, your system POSTs it to a URL someone registered, instead of them polling you.

the two-minute refresher

Push instead of pull: partners don't have to ask 'any new orders?' every minute.
Receivers are slow, down, or misconfigured, so delivery must be asynchronous with retries.
Delivery is at-least-once, so receivers must deduplicate by event ID.
Sign every payload (HMAC) so receivers can trust it.

also: webhooks · web hook

An HTTP callback: when an event happens, your system POSTs it to a URL someone registered, instead of them polling you.

Push instead of pull: partners don't have to ask 'any new orders?' every minute.
Receivers are slow, down, or misconfigured, so delivery must be asynchronous with retries.
Delivery is at-least-once, so receivers must deduplicate by event ID.
Sign every payload (HMAC) so receivers can trust it.