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Ian Hickson wrote:
<blockquote
cite="mid:Pine.LNX.4.62.0806102141080.6527@hixie.dreamhostps.com"
type="cite">
<pre wrap="">On Tue, 10 Jun 2008, Honza Bambas wrote:
</pre>
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<pre wrap="">Hi, I would like to ask for clarification of opportunistic caching spec
in Offline Web Applications, the article 4.9.1.9. Adding a resource whom
URI matches an opportunistic name space seems to be done only for top
level documents according to the article 4.9.1.9, cite: "If the resource
was not fetched from..." where the resource refers, as I understand, the
top-level document being navigated.
I didn't find any other place where a resource whom URI matched an
opportunistic entry would be added to a cache as opportunistically
cached. I would naturally expect it were part of the networking model,
article 4.7.5.1 - "Changes to the networking model", but I couldn't find
it, at least not explicitly, expressed.
Maybe I am missing something in the networking model spec: in article
4.7.5.1.4 when URI matches a name space it have to be "fetched
normally". Should implementers replace normal HTTP cache used for
writing by offline cache to store the resource in it? Instead of normal
HTTP cache?
</pre>
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<pre wrap=""><!---->
Resources can only be cached as opportunistically cached entries if a
browsing context is navigated, but it doesn't have to be a top-level
browsing context. The caching happens in the "Otherwise" clause of step 9
of the 4.9.1 Navigating across documents "navigation" algorithm.
If by "top-level" you don't mean a window/tab, but mean any iframe or
frame content document, as opposed to an image, a stylesheet, or some
such, then you are correct. The use case was really just replacing pages,
e.g. Flickr pages, when the whole site isn't cached. Do you think this
should be changed to opportunistically cache anything accessed?
</pre>
</blockquote>
(Sorry for late answer, email has probably been lost...)<br>
<br>
Thanks a lot for clarification.<br>
<br>
I was talking with my colleague about it and we both agree it would be
useful (and probably more easy to implement) for ANY resource being
fetched
inside of browsing context associated with an application cache to
opportunistically cache it and not just do it for results of
navigation, i.e. top-level document, iframe source and frame source. A
set of pictures/icons/css styles could be easily cached this way w/o
explicitly listing them in the manifest.<br>
<br>
At this point it would be good to say what really is
intention/motivation of opportunistic caching itself. Maybe I am
missing the purpose and potentially open a security hole or a kind of
attack this way.<br>
<br>
Honza Bambas<br>
<br>
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