- From: Ian Hickson <ian@hixie.ch>
- Date: Mon, 11 Jun 2012 21:48:18 +0000 (UTC)
- To: Andrew Oakley <andrew@ado.is-a-geek.net>, Boris Zbarsky <bzbarsky@MIT.EDU>
- Cc: whatwg <whatwg@lists.whatwg.org>
On Wed, 21 Mar 2012, Andrew Oakley wrote: > > I've noticed that some browsers (Firefox, Opera, IE) cache images > without following the HTTP expiry rules. This does not appear to be > permitted by the HTML5 specification. > > I've got a test case for this (with explanation) here: > http://ado.is-a-geek.net/expired/tests/image_cache_test.html > > Boris Zbarsky believes this behaviour is required for compatibility so I > think it is worth adding to HTML5. This was discussed on the Mozilla > bug tracker here: https://bugzilla.mozilla.org/show_bug.cgi?id=295942 > > How do other browsers handle this? It seems to be possible to get Opera > and IE to throw the image away by changing the src attribute on the img. > > Are there similar caches for any other type of object or is this just > images? For images in <img> elements I've now explicitly added spec-level support for such a cache. Not my favourite part of the spec, but if it's what implementors do interoperably... The spec is a bit vague, let me know if there's anything I can do to tighten it up while still being compatible with what UAs will implement. http://html5.org/tools/web-apps-tracker?from=7127&to=7128 On Wed, 21 Mar 2012, Boris Zbarsky wrote: > > Gecko has a similar (different in mechanism, but not too different in > effect) cache for stylesheets. I seem to recall that there was explicit > text about this as well, but I can't find it now. The closest I can > locate at the moment is the first paragraph at > http://www.whatwg.org/specs/web-apps/current-work/multipage/fetching-resources.html#fetch > > If the resource is identified by an absolute URL, and the resource > is to be obtained using an idempotent action (such as an HTTP GET > or equivalent), and it is already being downloaded for other reasons > (e.g. another invocation of this algorithm), and this request would > be identical to the previous one (e.g. same Accept and Origin > headers), and the user agent is configured such that it is to reuse > the data from the existing download instead of initiating a new one, > then use the results of the existing download instead of starting a > new one. Right now I haven't specced anything like this. Ideally I'd like to move all the CSS logic out of the HTML spec, since e.g.I assume that any caching for <link rel=styleseet> would also need to happen for @import. -- Ian Hickson U+1047E )\._.,--....,'``. fL http://ln.hixie.ch/ U+263A /, _.. \ _\ ;`._ ,. Things that are impossible just take longer. `._.-(,_..'--(,_..'`-.;.'
Received on Monday, 11 June 2012 21:48:45 UTC