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Lessons (12)

• Real-Time, Pub/Sub, Webhooks and CDC

  … Track webhook attempts durably, sign requests, bound retry age and concurrency, and deduplicate at consumers. CDC can capture …

• Extending Kubernetes: CRDs, Operators and Admission

  … require resource limits, block latest tags ValidatingAdmissionPolicy (no webhook needed) Built in and written in CEL. yaml apiVersion …

• Concurrency, Resilience & Distributed Workflows

  Keep backend systems correct under contention, failure and traffic spikes with idempotency, retries, circuit breakers, workers, webhooks, backpressure …

• Design an E-Commerce Checkout

  … Watch reservation-expiry rate, oversell rejections, payment UNKNOWN age, duplicate-key hits, webhook lag, successful-order rate and …

• Multi-Region and Disaster Recovery

  … A green database replica alone does not prove DNS, credentials, queues, webhooks and clients will recover correctly. Choose …

• Design a Reliable Notification System

  … provider ID plus Pending, Accepted, Delivered or Failed. Webhooks update outcomes idempotently. Retry transient errors with backoff; move …

• Resilient Service Calls: Retries, Breakers and Load Shedding

  … processing" if outcome is unknown - reconcile a later webhook with the same payment key Pattern What it does …

• Payment Retries: Prevent Duplicate Charges

  … conflicts, number and age of UNKNOWN attempts, provider webhook lag, and mismatch count between provider and database. Watch …

• Microkernel (Plugin) Architecture

  … Plug-ins are services called over HTTP/gRPC Webhooks, Shopify apps Trade-offs ✅ Strengths ❌ Weaknesses --- --- Extensible without touching …

• Serverless Architecture

  … JSON.stringify(result) }; }; When to use it ✅ Spiky or unpredictable traffic, event processing (uploads, queues, webhooks), scheduled jobs …

• Backend Design Scenarios

  … Treat the webhook as at-least-once: verify its signature, deduplicate its event ID, and update the payment …

• The Hot SKU Alert Problem

  … Provider webhooks, when available, should update the notification record idempotently using the provider message ID. Retries need exponential …