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THE INTERNET MACHINE
The Internet
MachineModule
02/04

THE HIDDEN ENGINE

02BACKEND

When we press a button, who does the work?

MODULE 02/04 · THE HIDDEN ENGINE

When we press a button, who does the work?

BACKEND

Behind the screen you tap, another machine wakes up to work: it checks, decides and answers. This book takes you into the engine room most people never see.

When you finish, you’ll understand

  • What requests and responses are, and how they travel
  • What each HTTP status code is telling us
  • Why a server must check every piece of data it receives
  • How a website knows who we are

The world of this book

A world of machines, commands, data pipes and control rooms

Who it’s for

Read it after Book 01 — or start here

Checking your access

Contents

6 chapters

  1. 01Requests and responses“When you press “Order”, what happens in between?”Open a pretend coffee shop and follow a single order from the browser to the server and back with an answer — both when it succeeds and when it fails.Lab 02: The server’s coffee shopFree · 15 min
  2. 02The server’s many doors“How does a server know what we want?”URLs, routes and HTTP methods like GET, POST, PUT and DELETE that tell the server what we want to do.Checking your access
  3. 03Never trust what you’re sent“What happens if someone edits a product’s price in their own browser?”Validation and the basics of security thinking — why a server has to be suspicious of everything first.Checking your access
  4. 04APIs: the menu machines use to talk“Where does a weather app get its data?”APIs and JSON — the common language that lets programs from different companies talk to each other.Checking your access
  5. 05Who are you?“Why do we log in once and the site remembers us all day?”Authentication, sessions, cookies and authorization — proving who you are versus checking what you may do, two ideas people often mix up.Checking your access
  6. 06When the machine breaks“How do engineers know a site has a problem before customers call to complain?”Error handling, logs, retries and monitoring — the art of failing gracefully.Checking your access

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