The performance of web sites and applications can be significantly improved by reusing previously fetched resources. Web caches reduce latency and network traffic and thus lessen the time needed to display a representation of a resource. By making use of HTTP caching, Web sites become more responsive

1. HTTP Caching
strategy

2. Cache

3. Brower cache

4. Headers

5. HTTP/1.0 • Pragma
• Expires

6. HTTP1.1 Cache-Control

7. Cache-Control
• no-cache
• no-store
• public
• private
• max-age || expires || (date – last-
modified)/10

8. Pragma > Cache-Control > Expires

9. Problem
• Browser 某个资源的缓存过期了，
但 Server 并没有更新该资源
• CSS修改，max-age: 86400

10. 缓存过期机制 — Last Modified

11. 缓存过期机制 — ETag

12. Defining optimal Cache-Control policy

13. Thank you