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Lessons (40)

• MVC, MVP & MVVM

  … from the data and logic behind it. How each works, how data flows, and where you meet them …

• VPC Endpoints, Transit Gateway and Hybrid Networking

  … cost in non-production. Troubleshooting with VPC Flow Logs Flow logs record accepted and rejected traffic per network …

• Layered (N-Tier) Architecture

  … are a logical split of code. - Tiers are a physical split onto different machines. mermaid flowchart LR subgraph …

• DSA Interview Patterns Cheat Sheet

  … decision flowchart mermaid flowchart TD S([Read the problem]) -- A{Input sorted,<br/ or 'find in sorted'?} A …

• What Is Apache Kafka?

  … Millions of messages/s per cluster mermaid flowchart LR subgraph Log["Partition 0 of topic 'orders'"] direction LR …

• Structural Patterns: How to Connect Objects

  … logger = new WinstonAdapter(winston); // the rest of the app is unchanged logger.log("info", "Server started"); mermaid flowchart …

• Frontend Testing Strategy

  … pure logic Best for pure functions: formatters, calculations, validation, reducers. ts // cart.ts export function cartTotal(items: { price …

• Sorting Algorithms

  … beating n log n Comparison sorts can't beat O(n log n). But if values are small …

• Heaps & Priority Queues

  … add at the end, "bubble up" mermaid flowchart LR a["1. Put new item<br/ at the end …

• Authentication, Authorization & API Security

  … logged in ✅ (session created) Use the Authorization Code flow with PKCE . It is the recommended flow for web …

• Multi-Account Strategy, Governance and Security Operations

  … auto-remediation GuardDuty Threat detection from CloudTrail, VPC Flow Logs, DNS and S3, EKS and malware scanning Security …

• D — Dependency Inversion Principle

  … editing business logic. - 🔗 The valuable code depends on the replaceable code, which is backwards. mermaid flowchart TB subgraph …

• Choosing an Architecture

  … a realistic example mermaid flowchart TB subgraph Mono["🏢 Modular monolith (one deployable)"] direction LR subgraph Ord["📦 Ordering: Hexagonal …

• Topics, Partitions & Offsets

  … the unit of parallelism Each partition is an ordered, append-only log stored on one broker (plus copies …

• Observability: Logs, Metrics & Traces

  … standard for collecting logs, metrics and traces. Instrument once, send the data anywhere. mermaid flowchart LR A[Service …

• Deploying & Operating Microservices

  … Simple, no extra capacity needed; old and new versions run side by side for a while. mermaid flowchart …

• JavaScript Essentials: Event Loop, Closures & this

  … run all microtasks, then one task The famous quiz js console.log("1"); setTimeout(() = console.log("2"), 0 …

• Creational Patterns: How to Make Objects

  … lightTheme); mermaid flowchart TB AF{{UI Factory}} -- L[Light factory] AF -- D[Dark factory] L -- LB[Light button …

• Kafka vs RabbitMQ & the Kafka Ecosystem

  … The Kafka ecosystem mermaid flowchart LR subgraph Sources DB1[(Postgres)] Apps[Microservices] Files[Logs / files] end DB1 -- Kafka …

• Big-O Notation Made Simple

  … mid - 1; } return -1; } Why is halving "log n"? mermaid flowchart LR A["1,000,000 items"] -- B …

• NestJS Core Concepts

  … every feature is a module , HTTP lives in controllers , business logic in providers , and a built-in dependency …

• Go Web Services with Gin

  … userID) c.Next() } } mermaid flowchart LR R([request]) -- Rec[Recovery] -- ID[RequestID] -- Log[Logger] -- A{Auth} A -- "Abort …

• Docker & Containers

  … logs -f api follow one service docker compose down stop (add -v to delete volumes too) mermaid flowchart …

• Trees & Binary Search Trees

  … That's a tree. mermaid flowchart TD CEO[👑 CEO] -- CTO[CTO] CEO -- CFO[CFO] CTO -- FE[Frontend lead …

• API Gateway, BFF & Service Discovery

  … one front door for many services](/img/microservices/api-gateway.svg) Without vs with a gateway mermaid flowchart …

• Onion Architecture & Clean vs Hexagonal vs Onion

  … All three share the same rule: 🎯 The business logic is at the centre and depends on nothing. Infrastructure …

• Clean Error Handling

  … logged, then forgotten; the caller thinks it worked try { await saveOrder(order); } catch (e) { console.log(e); } js …

• Which Pattern Do I Need?

  … Composite groups many children ; Decorator wraps exactly one . mermaid flowchart TB subgraph Same["Same shape: an object wrapping …

• React Hooks in Practice

  … runs before the next effect and on unmount return () = window.removeEventListener("resize", onResize); }, []); // dependency array mermaid flowchart LR …

• Hexagonal Architecture (Ports & Adapters)

  … string[]) { const loan = await borrowing.borrow(memberId, bookId); console.log( ✅ Borrowed ${bookId}, due ${loan.dueDate.toDateString()} ); } 3. Driven …

• Behavioral Patterns II: Chain, Template, Iterator, Mediator, Memento, Visitor

  … 2500 }); // "👔 manager approved" mermaid flowchart LR R[Request] -- H1[Logger] -- H2[Rate limiter] -- H3[Auth] -- H4[Route handler …

• Troubleshooting Playbook

  … Follow the same order each time. mermaid flowchart TD A[Something is broken] -- B[kubectl get pods: what …

• Message Queues & RabbitMQ

  … They send to an exchange , which routes messages to queues using bindings . mermaid flowchart LR P[Producer] -- "routing …

• Pods: Where Your App Actually Runs

  … a log collector reading shared log files. Init container: a short setup task that must finish before the …

• How a Web Request Works

  … typically passes through layers: mermaid flowchart LR R[Request] -- M["Middleware<br/ logging, auth, rate limit"] -- Rt[Router …

• Serverless Architecture

  … invest in structured logs, tracing (X-Ray / OpenTelemetry) Cost at sustained high load Containers or VMs can be …

• Your Practical Kubernetes Workflow

  … repository and makes the cluster match it. mermaid flowchart LR P[Pull request] -- G[Git: desired configuration] G …

• CQRS & Event Sourcing

  … fails if someone appended meanwhile }); } What you get Benefit Example --- --- 🧾 Complete audit log Every change, who made …

• KISS: Keep It Simple, Stupid

  … that isn't needed. Why complexity hurts mermaid flowchart LR C[More complexity] -- B[More places for bugs …

• AWS: Start Here

  … Install AWS CLI v2, then configure a named profile: bash aws configure sso --profile academy aws sso login …