Webhook

Webhooks invert polling: subscribe once, receive HTTP calls on events (conversion created, payment settled, partner registered) as they occur.

Reliability engineering

Producers must retry with backoff and sign payloads (receivers verify — spoofed webhooks are an attack surface); consumers must acknowledge fast, process idempotently (duplicates arrive by design), and queue-buffer against their own downtime. Dead-letter visibility on both sides turns “we missed events silently” into “we replayed the gap.” The affiliate postback is exactly this pattern with domain-specific parameters — the engineering discipline transfers verbatim.