- From: Dave Singer <singer@apple.com>
- Date: Wed, 30 Jul 2008 10:49:41 -0700
At 21:45 -0700 29/07/08, Robert O'Callahan wrote: >On Tue, Jul 29, 2008 at 11:20 AM, Dave Singer ><<mailto:singer at apple.com>singer at apple.com> wrote: > >Caching is on a full URL basis, of course. Once that is decided, >then yes, I think that pre-cached items for a given URL are in the >general cache for that site. > > >A site that uses this feature is likely to be fragile. It will have >to have z.html both in the archive and available directly from the >server, in case z.html is requested before the load of the archive >has finished. No. The definition *for MPEG-21 files* (which is all I have specified so far) is that accesses to the matching absolute URL (or relative URL) from within the archibe MUST find the resource within the archive. Since, as I say, this format starts with a directory, you know whether you have it or not. If ZIP or JAR files don't have a directory, then yes, they have a different trade-off and must load the whole thing before they know. You only need a resource *outside* the archive if it is requested 'nakedly' from outside the archive. If you do that, it might indeed hurt, but that's your choice as a site. The performance trade-off is very simple; if you have many small resources it may be much more efficient to ftch them as a package than individually. The downside is that this is a single connection in a pre-defined order whereas multiple resources could be fetched on parallel connections, and as needed. I doubt more connections to the same server gets you more bandwidth, however, and the mpeg-21 format also allows extent-based interleaving so that e.g. a lareg HTML page and and large JPEG can be loaded progressively together. >And if those copies ever get out of sync you're in very big trouble, >because depending on the context, either the archive version or the >direct version is likely to consistently win the load race, so just >occasionally some clients will get the wrong version. This seems >like a highly error-prone design. > >Rob > >-- >"He was pierced for our transgressions, he was crushed for our >iniquities; the punishment that brought us peace was upon him, and >by his wounds we are healed. We all, like sheep, have gone astray, >each of us has turned to his own way; and the LORD has laid on him >the iniquity of us all." [Isaiah 53:5-6] -- David Singer Apple/QuickTime -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.whatwg.org/pipermail/whatwg-whatwg.org/attachments/20080730/1e90abaa/attachment.htm>
Received on Wednesday, 30 July 2008 10:49:41 UTC