HTTP Caching

Webndsday
June 28, 2023

© David Buchmann

But... why?

Response time
Scale with load
Save resources and money

HTTP: Your browser chats with the webserver

Request

GET /path
Accept-Encoding: text/html

Response

HTTP/1.1 200 OK
Content-Type: text/html

<html>...</html>

HTTP verbs

GET
HEAD
POST
PUT
DELETE
...

HTTP response codes

1xx hold on
2xx here you go
3xx go away
4xx you fucked up
5xx I fucked up

twitter.com/stevelosh/status/372740571749572610

HTTP Cache Control

Cache control headers

Cache Expiration Model
Cache Validation Model

HTTP 1.1, RFC 2616, Sections 13.2 and 13.3

Cache Expiration

Cache-Control: s-maxage=3600, max-age=900
Expires: Thu, 15 May 2014 08:00:00 GMT

s-maxage
max-age
Expires (HTTP 1.0 - avoid!)

Cache validation

Application specific hash value on response
On request, cheap check if hash changed