Bug 29082 – html5 offline caches too much?

• Status: RESOLVED
• Resolution: INVALID
• Component: DOM

[frank goossens]

did some testing with html5 offline using safari 4.0.3 with webkit 531.9.1 (on win xp, but a friend confirmed this behavior on safari in iPhone OS 3.0.1) and according to those tests (and my no doubt limited understanding of how the offline appcache should work) it seems too much is stored in the offline cache?

an example on http://futtta.be/html5/offline.php

* offline.php:
** has "no-cache" and "expires" headers set in php
** shows server unix timestamp (so page is different at each request)

* manifest.php:
** declares mozchomp.gif as to be cached ("explicit", using "CACHE:")
** prohibits offline.php from being cached ("online whitelist", using "NETWORK:")

when accessing the page, safari stores data in the offline cache as it should, but when refreshing the page, the html-output of offline.php seems to be also fetched from the offline cache, as the timestamp does not change any more.

now please correct me if i'm wrong, but caching offline.php should not happen, even if it would not have been explicitly excluded in the manifest?

[Alexey Proskuryakov]

> ** has "no-cache" and "expires" headers set in php

HTTP caching rules, such as Cache-Control directives are always ignored for the purposes of offline application cache (the specification says so).

> ** prohibits offline.php from being cached ("online whitelist", using
> "NETWORK:")

Actually, the meaning of online whitelist is a bit different. These are resources that are allowed to be fetched from network - by default, all network loads are blocked for all uncached resources. It does not prohibit caching if it's otherwise requested.

Now, the main resource and the manifest are always implicitly added to the cache - otherwise, it would not be possible to use the Web application when offline. This is also mandated by the spec, and it matches what other browsers do.