- From: Amos Jeffries <squid3@treenet.co.nz>
- Date: Tue, 24 Jul 2012 19:11:10 +1200
- To: ietf-http-wg@w3.org
On 24/07/2012 6:39 p.m., Eric J. Bowman wrote: > "Adrien W. de Croy" wrote: >> a) does anyone actually use them? >> > Yes. > >> b) do they work? >> > I've never heard that they don't, nor run into any problems using them. > >> c) do we still need them? >> > Yes, otherwise I have to cache-expire for all changes to resource state, > without the option to declare certain changes insignificant. Take a > "weblog entry" resource which includes a # of comments counter, with a > link to a comment thread. XHR is used to synch the count, eventually. What type of server do you have which does not send strong ETag on binary-level changes anyway? If a cache called in asking for updates with one of your weak-ETag would your server send a new copy or a 304 even if some changes had taken place? If its going to emit a new copy why bother sending W/ in the first place? a new Etag can goes out and the cache is refreshed with that immediately. If its not going to emit a new copy on request, why not just send the old strong ETag? are you emitting 304 with a different weak-ETag? ... Range requests that make it to the origin make things weird, but they can be special-cased to either change the ETag to something more current before handling, or to use an old copy from which the ETag was generated. > I only change the Etag if the entry itself is edited. Since metadata > about the entry may change in the meantime, which isn't significant > enough to warrant a new Etag in my caching scheme, I preface with W/ to > indicate variance from the origin server not requiring cache expiration, > i.e. semantic equivalence. I assume you mean meta data inside the object itself (that counter, keywords list etc) ? AYJ
Received on Tuesday, 24 July 2012 07:11:44 UTC