Pattern 16 / COMMS
Use this when notifying an external system exactly when something happens.
Webhooks fits when notifying an external system exactly when something happens. Mechanism: store a subscriber URL and POST event payloads to it with retries and signatures. Use it for third-party integrations, SaaS callbacks, payment processors, and Git events. The toll: the receiver must be reachable, verify signatures, retry safely, and handle duplicates.
Third-party integrations, saas callbacks, payment processors, and git events.
Payment provider sending invoice.paid to a merchant endpoint.
Describe the pressure first, then the mechanism, then the cost. That keeps the design grounded.
Same pressure family