Backend Basics

Internet Basics

enter the site you want to visit
computer needs to find IP address to send request to
- query submitted to your ISP
- within ISP, the DNS takes the domain name and turns it into an IP address
going to the address
- request sent to IP address via HTTP (hyper text transfer protocol)
- request finds the fastest possible path to the server with the specified IP
  - this is not a direct journey --- it requires hopping from server to server until we arrive
server responds
- requested server finds out exactly what we're asking for
- server builds the right content --- often pulling info from a database
- server responds with any combo of HTML, CSS, and Javascript
browser renders the page

compiled on the server side
- server pulls everything together and constructs it before it is sent back as a response
can have different HTML, CSS, and/or Javascript that's being sent back every time a request is made

a generic stack:

Note:dashed row separates backend from frontend

HTML, CSS, and Javascript are almost always part of a stack
much more variance in the backend
- languages: ruby, python, scala, java, php, javascript, etc.
- databases: mongo, postgres, mysql, etc.

example of Reddit's stack:

backend is where the dynamic part of the site comes in

check if the user is logged in	sign up user	remove post from DB
figure out what js/html/css to send the user	add new post to DB	sort/rank posts
	create new comment	create subreddit
		add to newsletter
--------------------------------	--------------------	---------------------
⬇
HTML/JS/CSS	➡︎	website

stack for Web Developer Bootcamp (Udemy class):

example of going to a website and then searching for 'dogs':

Frontend		Backend
1. ask for homepage
		2. send back home page content
3. browser renders home page
4. user enters 'dogs' in the search and submits form
		5. finds all posts in DB about 'dogs'
		6. sends back HTML for the search results page
7. browser renders search page