Search

Lessons (40)

• A WhatsApp OTP Is Only Single Use If You Make It So

  Design one-time passcodes that can be consumed exactly once, even when two requests arrive in the same …

• Which Pattern Do I Need?

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

• Design a Logging and Monitoring Platform

  … Define which signals must survive and which may be sampled. Practical response 1. Batch at agents with bounded …

• S3: Store Files Safely

  … Uploading a new object under the same key replaces the current object; versioning can retain earlier versions. A …

• Payment Retries: Prevent Duplicate Charges

  … Reject the same key with different parameters. 2. Claim work atomically and send a stable provider idempotency key …

• Topics, Partitions & Offsets

  … JSON.stringify({ type: "OrderPaid" }) }, // same partition, after Placed { key: "order-42", value: JSON.stringify({ type: "OrderShipped" }) }, // same partition …

• Onion Architecture & Clean vs Hexagonal vs Onion

  … they're the same core idea All three were created to fix the same problem with classic layered …

• Frontend Security

  … POST /transfer (🍪 bank cookie attached automatically!) B-- V: 💸 transfer done Defences: Defence How it helps --- --- SameSite=Lax or …

• Debug Latency Like an Investigator

  … Compare before/after traces for the same endpoint and split latency into pool wait, SQL execution and downstream …

• Pods: Where Your App Actually Runs

  Learn what a pod is, why it is not the same as a container, the common pod statuses …

• DRY: Don't Repeat Yourself

  … DRY is about rules and facts , not about lines of text that happen to look the same. The …

• Code Profiling

  … a wide bar means that stack frame consumed a large share of sampled CPU time. Width matters; height …

• AWS Messaging: Queues, Topics and Events

  … It is not the same as the stable message ID. Now send another sample and receive it without …

• Docker & Containers

  Package your app with everything it needs so it runs the same everywhere. Images, containers, Dockerfiles, layers, volumes …

• Serverless: Lambda and API Gateway

  … Repeated requests with the same key should return the established result; the same key with conflicting content should …

• Structural Patterns: How to Connect Objects

  … each wraps a function and returns a function with the same shape const withLogging = (fn, name) = async (...args …

• Data Preparation and Model Training

  … A training pipeline should make the same transformations at training and prediction time, preserve the meaning of each …

• State, Remote Backends, and Locking

  … Two independent states managing the same object create competing owners. Local state is convenient for a single-person …

• L — Liskov Substitution Principle

  … steering wheel, pedals and gears to work the same way. If one "car" steers backwards, it isn't …

• Code Smells & Refactoring

  … A code smell is the same: a surface sign that probably points to a deeper design problem. Refactoring …

• CI/CD and Reviewed Production Changes

  … Two jobs writing the same state should not race; use both backend locking and CI concurrency controls. Commands …

• Design a Ride-Sharing Service

  … The geo index lists the same driver as available, but its location is already ten seconds old. What …

• JavaScript Language Fundamentals

  … copying the variable only copies the address , and both variables point at the same house. ![Primitives are copied …

• Backend Languages: Node.js, Go, Python & Rust

  … How each handles concurrency, what it's best at, and the same tiny API written in all four …

• Behavioral Patterns I: Observer, Strategy, Command, State

  … Same goal (get from A to B), interchangeable algorithms, picked at runtime. Problem: you have several ways to …

• Observability and Incident Response

  … Assign an incident lead, record hypotheses and mitigation decisions, then verify rollback or repair with the same customer …

• 500 Users Upload Documents at Once: Design the Background Job Pipeline

  … At 9:00 a.m., 500 users upload at the same time, and the first version of the …

• Resilient Service Calls: Retries, Breakers and Load Shedding

  … Services need the same boundaries. A practical payment dependency text Checkout - payment provider is slow - wait only until …

• What Is Clean Code?

  … A,E bad Same logic, two styles Both functions below do exactly the same thing. Which one would …

• AI Specialties and Real-World Examples

  … Evaluate under dim light and different packaging, not only clean sample photographs. Language and speech: measure the actual …

• Scaling, Load Balancing & Rate Limiting

  … useful but usually a smell Sticky sessions route the same client to the same backend, often with a …

• Creational Patterns: How to Make Objects

  … both come from the same factory return [uiFactory.createInput(), uiFactory.createButton()].map((c) = c.render()).join(""); } buildLoginForm(prefersDark …

• Hexagonal Architecture (Ports & Adapters)

  … Exactly the same rule as Clean Architecture, drawn differently. A complete example: a library loan system 1. The …

• React vs Vue vs Angular

  The same counter in three frameworks, a side-by-side comparison of reactivity, templates, state and tooling, and …

• Event-Driven Patterns, Step Functions and Reliable Lambdas

  … make handlers idempotent , so running twice gives the same result as running once. text handler(event): validate(event …

• Choosing an Architecture

  … Choosing an architecture is the same: match the style to the journey you're actually making , meaning your …

• Small Functions That Do One Thing

  … one-job.svg) A function should work the same way: do one thing, do it well, do only …

• Clean Architecture

  … Clean Architecture does the same for code: your business rules (the valuable part) depend only on simple interfaces …

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

  … Retry the same event ID and require idempotent handling. On browser reconnect, read missing events or refresh current …

• Database Relations & Foreign Keys

  … Do not split tables merely because two columns look related; a profile with the same lifecycle can live …