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Lessons (40)
- Microkernel (Plugin) Architecture
A small, stable core plus independent plug-ins that add features. How VS Code, browsers, Webpack and ESLint …
- Hexagonal Architecture (Ports & Adapters)
… The core: domain + ports + use case ts // core/domain/Loan.ts export class Loan { constructor(readonly bookId: string …
- Onion Architecture & Clean vs Hexagonal vs Onion
… infrastructure, UI, tests Implementations of the interfaces, web framework, DB, external APIs SqlOrderRepository , controllers, EF Core / Prisma mermaid …
- Frontend Performance & Core Web Vitals
… Google measures exactly these three feelings with the Core Web Vitals . ![The three Core Web Vitals and their …
- System Design Interview Framework
… clarify requirements, estimate scale, draw the core path, then deep dive into risks and recovery](/img/system-design …
- Choosing an Architecture
… Hexagonal + tactical DDD"] oa[HTTP adapter] -- oc((core)) -- ob[(Postgres adapter)] end subgraph Cat["📦 Catalog: vertical slices (mostly …
- Finding Service Boundaries with DDD
… where to invest mermaid flowchart LR Core["⭐ Core domain<br/ your competitive advantage<br/ e.g. recommendation engine …
- SQL Interview Query Drills
… For an average per class, use a correlated subquery or partitioned window function. Q26: Third-highest distinct salary …
- Transactions, Indexes & Concurrency
… Covers PDF questions 8-11 and 18.  Three correct loading strategies Need Use Watch out for --- --- --- One related …
- Clean Architecture in Depth
… That's Dependency Inversion (the D in SOLID) at architecture scale. mermaid flowchart LR subgraph Core["Application core …
- ACID, Transactions & Locks
Make multi-step changes correct with atomic transactions, isolation choices, constraints and short-lived locks. The bank-transfer …
- React vs Vue vs Angular
… a flexible core (UI components) and you pick the other pieces yourself (router, state, forms). Huge community. - Vue …
- Event-Driven Architecture
… 2, "occurredAt": "2026-09-28T10:15:00Z", "source": "ordering-service", "correlationId": "req-7f3c", "data": { "orderId": "o42", "customerId": "c7 …
- Frontend Testing Strategy
… One function in isolation Vitest / Jest ⚡⚡ Logic is correct Integration / component ⭐ Components working together, as a user sees …
- Design an E-Commerce Checkout
Keep browsing scalable while protecting the correctness-critical path: inventory reservation, idempotent payment, order creation and durable events …
- Batch vs Stream and Data Modeling
Choose when work runs and shape data for correctness first, then deliberately denormalize proven read bottlenecks. ![Batch runs …
- Releases, Observability and Production Safety
… artifacts, reversible migrations and a measured rollback trigger. Correlate logs, metrics and traces with request IDs; alert on …
- Distributed Coordination: Consensus, Heartbeats and Gossip
… membership at scale Gossip Eventual convergence Was data corrupted? Checksum Detect accidental modification Raft elects a leader and …
- Backend Languages: Node.js, Go, Python & Rust
… thousands of goroutines"] S{{Go scheduler}} -- G1[goroutine] & G2[goroutine] & G3[goroutine] & G4[goroutine …] S -- C1[CPU core …
- Time, Consistency and Distributed Transactions
Reason about clocks, ordering, split brain, locks, CRDTs and transactions without promising impossible global certainty. ![Distributed correctness: clocks …
- DBMS Foundations, Keys & Normalization
… Normalized tables protect correctness; a read-heavy path may use a controlled denormalized projection. ![Interview map: keys identify …
- Storage Engines & Database Operations
… it can copy accidental deletion or corruption. Keep independent backups, define retention, encrypt them, and test restoring a …
- Why Kubernetes?
… images or scattered files ConfigMaps and Secrets The core idea: desired state ⭐ You don't tell Kubernetes how …
- Clean Architecture
… same idea, drawn as an onion. - All three share the core rule: business logic in the centre, infrastructure …
- API Gateway, BFF & Service Discovery
… Guests don't wander the corridors looking for housekeeping, the restaurant or the spa; they ask at the …
- Normalization & Denormalization
… Final 3NF core: customers products orders order items --- --- --- --- customer id PK product id PK order id PK order …
- SOLID at a Glance
… depend on abstractions"] -- Swap L["L — subtypes behave correctly"] -- Swap Swap -- O["O — extend without editing"] O -- Goal …
- O — Open/Closed Principle
… new behaviour is plugged in, the core stays untouched](/img/solid/ocp-plugins.svg) With classes and TypeScript …
- Which Pattern Do I Need?
… Reverse proxy, CDN, service mesh sidecar Adapter Anti-corruption layer Command Message queues, CQRS commands Mediator Saga orchestrator …
- What Is Apache Kafka?
… Adding a new consumer requires zero changes to the producers. Core vocabulary Term Meaning Analogy --- --- --- Event / record / message …
- Kubernetes Cluster Architecture
… kube-system"] c1[CoreDNS] --- c2[kube-proxy] end end bash kubectl create namespace team-shop kubectl get pods …
- React Fundamentals
… And React's core idea fits in one line: 🎯 UI = f(state) . You describe what the screen should …
- Monolith vs Microservices
… many independent shops, each with its own staff, stockroom and opening hours, connected by shared corridors. A mall …
- Pods
… requests: guaranteed minimum, used for SCHEDULING cpu: "250m" 0.25 of a CPU core memory: "256Mi" limits: maximum …
- SQL vs NoSQL Databases
… complex questions, ACID transactions keep money and inventory correct, and SQL is a universal language. Examples: PostgreSQL, MySQL …
- Graphs: BFS & DFS
… Follow one corridor as deep as it goes; at a dead end, backtrack to the last junction and …