Thursday, 6 May 2010
RFC5861: HTTP Stale Controls
On a bit of a roll, RFC5861: HTTP Stale Controls has (finally) been published as an Informational RFC.
As discussed before in “ Two HTTP Caching Extensions,” these are very useful ways to hide latency and errors from your end users. While they’re most useful in HTTP gateway caches (a.k.a. reverse proxy caches / accelerators), very latency-sensitive sites might find them useful as well when working with “normal” proxy caches.
Both are implemented in Squid 2.7. Not only does Squid respect both response Cache-Control directives, but it also allows you to tweak its behaviour using the stale-while-revalidate and max-stale refresh_pattern options. Squid 3.2 should have them when it’s released, and I understand that Apache Traffic Server will have stale-while-revalidate available soon as well.