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Lessons (28)

• Resilience Patterns

  … 30 000, // try again after 30 s }); breaker.fallback(() = []); // no recommendations? show none instead of an error breaker …

• AI Specialties and Real-World Examples

  Explore vision, language, speech, recommendations, anomaly detection, forecasting, reinforcement learning, and generative systems. Choose a branch by its …

• What to Learn in AI, and in What Order

  … vision, language, speech, recommendations, forecasting, and reinforcement learning. - [Developer plan and capstone](/learn/ai/developer-roadmap-and-capstone …

• The L6 System-Design Thinking Loop

  … Keep browsing, recommendations, email, and analytics away from that write path. A queue can smooth non-critical work …

• Domain-Driven Design: Strategic Design

  … Build in-house, best people, richest model Personalised recommendations, dynamic pricing 🧰 Supporting Necessary and specific to you …

• API Gateway, BFF & Service Discovery

  … orders.map(({ id, status }) = ({ id, status })), recommendations: recs.map(({ id, title, thumbUrl }) = ({ id, title, thumbUrl })), }); }); A Next.js …

• Event-Driven Patterns, Step Functions and Reliable Lambdas

  … AWS recommends a visibility timeout of at least six times the function timeout plus the configured batch window …

• React Internals & Concurrent Rendering

  … Place boundaries around meaningful sections so a slow recommendation panel does not hide an already-available order summary …

• Multi-Region and Disaster Recovery

  … Restaurant menus Serve regional cache; refresh later. Search/recommendations Degrade or use stale replica. Images Multi-region object …

• Flash Sale: 10 Million Buyers, No Oversell

  … Give every purchase an idempotency key, reconcile reservations/orders/payments, and isolate sale traffic from browsing and recommendations …

• Timeouts, Retries & Backpressure

  … in durable queue It can arrive later. Product recommendation Drop temporarily It is optional. File conversion Accept only …

• Design an E-Commerce Checkout

  … design-l6/ecommerce-checkout.svg) Catalog, search and recommendations can be cached and eventually consistent. Checkout cannot: reserve …

• Resilient Service Calls: Retries, Breakers and Load Shedding

  … Load shedding Rejects low-value work early Disable recommendations during a flash sale. Queue + backpressure Smooths bounded async …

• What Is Artificial Intelligence? A Developer's Guide

  … must follow enforced rules For a bookstore, a recommendation model can rank books, but SQL still checks stock …

• Brokers, Replication & Durability

  … acknowledged write can ever be lost: Setting Where Recommended --- --- --- replication.factor Topic 3 min.insync.replicas Topic / broker …

• Monolith vs Microservices

  … payments must keep working when recommendations are down. ❌ Bad reasons: - "Netflix does it." (Netflix has thousands of engineers …

• SQL vs NoSQL Databases

  … scale Cassandra Graph Nodes and relationships Social networks, recommendations, fraud detection Neo4j A document example (MongoDB) js // One …

• Authentication, Authorization & API Security

  … It is the recommended flow for web, mobile and single-page apps. Authorization models Model Idea Example --- --- --- RBAC …

• Finding Service Boundaries with DDD

  … domain<br/ your competitive advantage<br/ e.g. recommendation engine"] -- CoreHow["Build in-house<br/ with your best …

• Frontend Security

  … JS can't read it Mitigated by SameSite ✅ Recommended for sessions / refresh tokens http Set-Cookie: session=abc123 …

• Choosing an Architecture

  … image resizing"] K -- Rec["🏙️ Recommendation microservice<br/ (extracted: heavy ML scaling)"] Each part uses the style that …

• Vertical Slice Architecture & the Modular Monolith

  … enforce the boundaries with tooling. - It's the recommended starting point for most systems, with an easy path …

• Cost Optimization and the Well-Architected Framework

  … teams, products and environments Compute Optimizer Right-sizing recommendations for EC2, EBS, Lambda and ECS Trusted Advisor Checks …

• IAM: Who Can Do What

  … person or workload temporarily assumes IAM Identity Center Recommended sign-in for people in an organization Least privilege …

• Collaborative Document Editing & Real-Time Sync

  … server Server can be a relay plus persistence Recommendation: a server-sequenced model with a single writer per …

• Caching & Redis

  … wait for refresh Use this for feeds, recommendations, catalogs and dashboards—not for an authorization decision or a …

• Practical Project: Deploy a Real CRM App on EKS

  … Only as a rollback path during migration Migration recommendation: keep the existing EC2 frontend running. Deploy the new …

• Practical Lab: S3 File Upload and CloudFront Delivery with NestJS

  … an IAM role (production, recommended) When the API runs on AWS, give the compute an identity instead of …