Senior LevelREST APIs & Web Services
How do you build resilient Webhook delivery systems with Dead Letter Queues (DLQ)?
❓ Interview Prompt: Explain Webhook delivery architecture, exponential retry backoff schedules, worker queues, Dead Letter Queues (DLQ), and manual replay tooling.
Building enterprise-grade webhook delivery systems that reliably deliver millions of notifications even when customer endpoints experience outages:
Delivery Architecture:
1
Worker Queue: Webhook worker reads events from Redis/RabbitMQ.
2
Exponential Retry Schedule: Retries failing endpoints up to 10 times over 24 hours (e.g. at 1m, 5m, 15m, 1h, 6h, 12h, 24h).
3
Dead Letter Queue (DLQ): If all 10 retry attempts fail, the webhook payload is moved to a DLQ.
4
Admin UI Replay: Exposes a dashboard for developers to inspect failed payloads and trigger manual one-click replays after fixing their server!
Code Implementation Example
typescript
export async function processWebhookDelivery(event: WebhookEvent) {
try {
await sendHttpWebhook(event.targetUrl, event.payload, event.signature);
} catch (err) {
if (event.attemptCount >= MAX_RETRIES) {
// Move to Dead Letter Queue (DLQ) for inspection & manual replay!
await dlqQueue.add(event);
await notifyUserWebhookDisabled(event.tenantId, event.targetUrl);
} else {
// Schedule next exponential retry...
await retryQueue.add(event, { delay: calculateBackoff(event.attemptCount) });
}
}
}💡Routing failed webhooks to Dead Letter Queue (DLQ) after retry exhaustion.
🎯 Interview Key Takeaway
Route failed webhooks to Dead Letter Queues after retry attempts exhaust, providing manual replay tools for developers.
#Webhooks#DLQ#Dead Letter Queue#Retry#Senior
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