Cache-Control and Last-Modified and ETag, oh my! @ Kansas City Developer Conference

Ever wonder exactly what combination of Cache-Control, Last-Modified, Expires, ETag, Vary, and Pragma headers will keep your content cached by browsers just long enough? And what exactly is a HTTP 304 anyway?

In this talk, we’ll take a look around at the available HTTP caching headers, what their values mean, and how browsers and proxies react. We’ll cover the best practices on client cache invalidation, the benefits of sending a Not Modified response, and briefly talk about the changes in HTTP 2.0 (SPDY) around caching.

Transcript

1. Cache-control and Last-Modified and ETag, Oh My! ! @adunkman
2. Expires, Pragma, Vary Cache-Control Conditional Requests A Few Tips The Future of Caching
3. Expires, Pragma, Vary Cache-Control Conditional Requests A Few Tips The Future of Caching
4. Wed, 14 May 2014 22:36:20 GMT
5. Pragma: no-cache
6. Pragma: no-poll
7. Vary: User-Agent
8. Expires, Pragma, Vary Cache-Control Conditional Requests A Few Tips The Future of Caching
9. Expires, Pragma, Vary Cache-Control Conditional Requests A Few Tips The Future of Caching
10. no-cache no-store no-transform
11. max-age s-maxage
12. must-revalidate proxy-revalidate max-stale
13. private public
14. no-cache! no-store! no-transform! max-age! s-maxage! must-revalidate! proxy-revalidate! max-stale! public! private
15. Quiz
16. Expired responses ! will not be cached. _FALSE_
17. It’s perfectly okay! to set an Expires header! 30 years in the future. _FALSE_
18. If a response has both! Expires: <now + 1 year>! and! Cache-Control: max-age=15! how long is it cached?
19. Expires, Pragma, Vary Cache-Control Conditional Requests A Few Tips The Future of Caching
20. Expires, Pragma, Vary Cache-Control Conditional Requests A Few Tips The Future of Caching
21. Last-Modified! If-Modified-Since
22. Etag! If-None-Match
23. Expires, Pragma, Vary Cache-Control Conditional Requests A Few Tips The Future of Caching
24. Expires, Pragma, Vary Cache-Control Conditional Requests A Few Tips The Future of Caching
25. Always changing:! prevent caching.
26. Cache-Control: no-cache
27. May change:! prevent using a cache! without revalidation first.
28. Expires: <in the past>! Cache-Control: must-revalidate, max-age=0
29. Never changes:! Cache forever*.
30. Expires: <1 year from now>! Cache-Control: max-age=31556926
31. Be careful what ! you say in public.
32. Vary: Accept-Encoding
33. example.com?but_why=lame
34. Expires, Pragma, Vary Cache-Control Conditional Requests A Few Tips The Future of Caching
35. Expires, Pragma, Vary Cache-Control Conditional Requests A Few Tips The Future of Caching
36. <link rel=“prefetch” href=“…”>
37. Link: <url>; rel=prefetch
38. <link rel=“subresource” … >
39. Link: <url>; rel=subresource
40. SPDY
41. mod_spdy
42. X-Associated-Content: ! "full-url":<priority>
43. Expires, Pragma, Vary Cache-Control Conditional Requests A Few Tips The Future of Caching
44. Thank you! ! @adunkman