On 24 September 2010 21:27, Alexey Proskuryakov <[email protected]> wrote: > > 24.09.2010, в 17:31, Gavin Peters (蓋文彼德斯) написал(а): > >> - Cost. Why make requests longer than they need to be? > > If used correctly, this will make responses longer, too (due to Vary: > X-Purpose). Due to the nature of Vary, it will need to be sent with every > response for the resource, not just those that are in response to prefetch > requests.
I think I might be missing this point. For the purposes of prefetching, I think that once you send out a "Vary: X-Purpose" header, you've basically opted out of permitting prefetching. Why wouldn't such a site send out a non-cacheable failure to prefetching requests? A 500 or 404 would likely not cause a cache discard, and so an eventual user navigation will just cause cache validation; but that's OK: the prefetch wouldn't have resulted in network activity if the cache was fresh anyway. Is there another case I'm forgetting or not understanding? I can see how this might be different in the "X-Purpose: preview" case, but that cat's out of the bag. > Eric has made another good point in Bugzilla - we don't explain the purpose > in lots of other cases, from loading into a display:none frame to > XMLHttpRequest. Why should Prefetch be all the different? That I don't have a good answer to; we don't. For prefetching browsers traditionally have, but for these cases they haven't. Prefetching is not all that different than a display:none frame I suppose. - Gavin _______________________________________________ webkit-dev mailing list [email protected] http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
