[whatwg] AppCache and SharedWorkers?
ap at webkit.org
Fri Mar 27 00:44:07 PDT 2009
On 27.03.2009, at 0:16, Drew Wilson wrote:
> Are you suggesting that user agents may want to require explicit
> user permission when any application invokes
> ApplicationCache.update()? That might be a reasonable approach if a
> given user agent wants to enforce some kind of "no silent update"
Asking for permission each time will condition users to click "Allow"
without thinking, which will be just a nuisance. But the big
difference between normal offline applications and persistent workers
as proposed is that the user explicitly starts the application in a
browser window - either by opening an URL, or using a desktop link. On
the other hand, a persistent worker "would be started up on every
subsequent invocation of the user agent until it has been killed".
Besides, application cache update is usually triggered by simply
opening a document from the cache, not by an explicit update() call.
See 5.8.6 (the application cache selection algorithm): "If document
was loaded from an application cache<...> Invoke the application cache
update process for that cache and with the browsing context being
navigated." So, if you have e.g. a worker that checks google.com e-
mail and updates a status icon with the number of unread messages,
then it will be updated whenever the user goes to read the mail online
(assuming the worker source lives in the same cache as the application
itself, which I think makes sense).
Thus, I think that the way for a persistent worker to manipulate the
cache is by opening a browser window with an HTML document.
- WBR, Alexey Proskuryakov
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