Intro to HTTP

Projected Time

Approximately 2 hours

Prerequisites

How the Internet Works

Motivation

HTTP is the backbone of the web, for both human users and other programs (APIs)

Specific Things To Learn

What is the HTTP standard?
HTTP Request
HTTP Response
HTTP Header
HTTP Status Codes

Materials

HTTP Crash Course - first 17 minutes are all that matter but feel free to watch the whole thing as it covers Postman
b0rk’s Anatomy of an HTTP Request

Lesson

Watch the crash course video above
Ask the SEAM for a paper copy of the HTTP Zine by Julia (b0rk)
Work through the rest of the practice

Guided Practice

Premade Node Web Server

Node has a library as http.request. It is called http.server.

For a prebuilt version
npm install -g http-server
http-server
This will start a web server that will serve files in the current directory
Run it in one of your project folders, such as your portfolio
It will announce that it started a server on two sockets. We’ll cover that again in Networkin
Open the location in your browser: http://127.0.0.1:8080

Build Your Own Web Server

Tutorial to do it yourself:

Node.js lab exercise, Part 2

Now make some requests against it with your browser and also curl. Try logging all the data made available to you in the request object, such as headers.

From the Command Line

Instead of using a browser, let’s see what’s happening underneath.

brew install telnet if not installed
format is telnet <server> <port> (note: it’s not a colon like in a URL)
telnet www.google.com 80
It will connect and inform you of the escape character
type GET / HTTP/1.0 then enter twice. This is the smallest valid HTTP request
A Google web server will spit out the Google home page

Questions

Why do you have hit enter twice?
Why does the 80 port not show up in the browser?

Challenge

User Agent is a voluntary header that browsers send identifying themselves.

Extend your Node web server above to console.log which browser the user is uses. Try out mobile browsers to see how they look different.

Check for Understanding

Sync up with your pair or another apprentice who is available and go through the following exercises.

Paper Request

Your the client: on paper write out a basic HTTP request
Hand it to your pair. They are the server.
If the request is valid, write out a valid response and give it back to them
If the request is not valid, identify how to fix it.

How to know what is required?

If you’re curious what each required piece is, check out this simplified HTTP specification. The complete spec is huge and uses a formal mathematical language if you want to go down a rabbit hole.