[whatwg] Application deployment
singer at apple.com
Wed Jul 30 10:49:41 PDT 2008
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
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.
>"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]
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