System Integration: Scenario-Based Questions

Webhooks allow external systems to notify your service in real-time. But they must be processed reliably and securely — without losing data or exposing vulnerabilities.

📥 Ingestion Strategies

• Accept POST requests on a dedicated endpoint.
• Immediately acknowledge receipt (HTTP 2xx) to avoid retries.
• Push payload to a durable queue for async processing (e.g., SQS, Kafka).

🔐 Security Controls

• Validate HMAC signatures or shared secrets.
• Restrict to known IP ranges or use mTLS (if supported).
• Limit payload size and parse defensively.
• Rate-limit by sender or token.

🔁 Reliability Features

• Retry failed processing with exponential backoff.
• DLQ (dead letter queue) for persistent failures.
• Idempotency checks using event ID or hash fingerprint.
• Monitor ingestion latency, failure rates, and event skew.

🧰 Tooling

• Webhooks testing tools: RequestBin, ngrok tunnels, Webhook.site
• Frameworks: Stripe webhook handler, FastAPI background tasks, Celery, AWS Lambda + API Gateway

✅ Best Practices

• Separate ingestion from processing to reduce coupling and increase durability.
• Store raw payloads with timestamp for audit/debug.
• Use signed events and validate timestamp freshness.
• Design for at-least-once delivery — ensure downstream idempotency.

🚫 Common Pitfalls

• Blocking webhook response until full processing is complete.
• Failing to verify signature → accepting spoofed events.
• No retry or visibility into dropped events.

📌 Final Insight

Webhooks are powerful but fragile without protection. Design your pipeline with durability, validation, and traceability — and you’ll gain real-time integration superpowers.