Networking

Every time you type a web address and press Enter, a hidden lookup runs before the page even starts loading. Your computer does not know where the website lives. It only knows its name. This post explains exactly how DNS turns that name into a number your computer can connect to. In simple steps. The Problem: Names vs Numbers Every device on the internet is reached by an IP address — a number like 142.250.72.196. Routers move traffic using these numbers, not words. ...

Every time you see the padlock in your browser, two computers perform a secret handshake. They agree on a secret key — without ever sending that key across the internet. And your browser checks that the server really is who it claims to be. This post explains exactly how that works: HTTPS, the TLS handshake, keys, and certificates. In simple steps. The Problem: Plain HTTP Is Readable HTTP sends everything as plain text. Your password, your messages, your card number — all of it. ...

In the previous tutorial, we used Docker Compose to run an app with a database. We briefly mentioned volumes and networking. Now let’s understand them properly. These two topics answer two important questions: Volumes: How do I keep data when a container is removed? Networking: How do containers talk to each other? Why Containers Lose Data Containers are designed to be temporary. You can create them, destroy them, and replace them. This is a feature, not a bug — it makes containers predictable and easy to deploy. ...

Every app needs to talk to the internet. On Android, you use Retrofit. On iOS, you use URLSession. Two different libraries, two different APIs, two different codebases. In KMP, you use Ktor Client — one networking library that works on every platform. Write your API calls once in commonMain, and they work on Android, iOS, Desktop, and Web. What is Ktor? Ktor is a networking framework by JetBrains (the same team behind Kotlin). The client side lets you make HTTP requests from shared code. ...

Every real app needs data from the internet. A weather app calls a weather API. A social app loads posts from a server. A store app fetches products from a backend. Retrofit is the most popular library for making HTTP requests in Android. In this tutorial, you will learn how to use it with Compose to build a screen that loads, displays, and handles errors from a real API. What is Retrofit? Retrofit is an HTTP client library by Square. It turns your API into a Kotlin interface: ...