System 03 · Distributed Resilience
Resilient Webhook Relay & Idempotent Broker
Business Problem
Payment gateways (Stripe, Mollie, Adyen) retry aggressively on timeouts. Naive webhook receivers double-charge customers, duplicate ERP inventory, or drop critical payment confirmations during downstream outages.
System Architecture
Axum ingestion receiver on port 8003 with background Tokio dispatch worker, transactional PostgreSQL idempotency index, and a Vue 3 monitoring dashboard for inspection and manual replay.
Engineering Highlights
Cryptographic HMAC-SHA256 signature verification prior to payload storage, strict exactly-once idempotency semantics, exponential backoff retry engine (10s → 1m → 15m → 1h), and visual Dead Letter Queue (DLQ) single-click replay.
Tangible Business ROI
Guarantees zero lost transactions during ERP maintenance windows, protecting checkout revenue and avoiding customer payment disputes.