[Bug 14702] appcache: always up-to-date applications

https://www.w3.org/Bugs/Public/show_bug.cgi?id=14702

Israel Hilerio [MSFT] <israelh@microsoft.com> changed:

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--- Comment #29 from Israel Hilerio [MSFT] <israelh@microsoft.com> 2012-01-13 19:43:09 UTC ---
We (Microsoft) were asked by our partners and our web properties to expand the
use of AppCache beyond offline scenarios.  These web properties were not
interested in providing offline capabilities to their customers but rather
deliver content quickly to them.  Like Adrian explained below, we introduced a
new tag into the manifest file that allows web properties who want to opt-in
into this new functionality to overwrite the default behavior of their
AppCache.  This new tag prevents the master entry from being cached into the
AppCache but allows all the other resources to be cached.  As Anne summarizes
in thread below, there are issues with using HTTP caching to enable this
scenario.

One common scenario where this could be problematic relates to caching of
outdated library versions.  In other words, what happens if a non-cached master
entry needs a new version of a library that was cached and the name of the new
and old libraries are the same.  This problem exists today, independent of
AppCache, for libraries served with long-lived HTTP caching headers. 
Fortunately, major sites have dealt with this by versioning their library URIs
to force loading of new libraries when their main page is updated.  We believe
that this best practice can be recommended for sites who want to use AppCache
as a perf optimization tool and not an offline mechanism.  We’ve discussed this
with Hotmail, Bing, and Facebook and they agree that this is useful
functionality for the AppCache feature to expose.

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Received on Friday, 13 January 2012 19:43:17 UTC