[webkit-dev] About bypassing caches for URLs listed in Fallback and/or Network section in a HTML5 Offline Web Application

[Lianghui Chen]

> (b) Revalidating cached items once their freshness lifetime expires.

But this will create dependence on the http stack cache implementation? And for some hosting services, the site might not allow the web application to change the http headers in the response?


-----Original Message-----
From: Maciej Stachowiak [mailto:mjs at apple.com] 
Sent: Tuesday, July 13, 2010 11:41 AM
To: Lianghui Chen
Cc: webkit-dev at lists.webkit.org
Subject: Re: [webkit-dev] About bypassing caches for URLs listed in Fallback and/or Network section in a HTML5 Offline Web Application


On Jul 13, 2010, at 8:14 AM, Lianghui Chen wrote:

> Hi, I have asked this same question in (whatwg at lists.whatwg.org), but haven't got many responses, so I want to ask here again.
> 
> In spec HTML5 for offline web application (http://www.whatwg.org/specs/web-apps/current-work/#offline) chapter 6.6.6, item 3, 4, 5 state that for resources that is in online whitelist (or has wildcard whitelist), or fallback list, it should be fetched "normally".
> 
> I would like to know does it mean the user agent (browser) should bypass its own caches (besides html5 appcache), like the WebKit cache and browser http stack cache?

As the spec is currently written, I think the browser should not bypass its own caches. Other caches should have their normal behavior, and will revalidate once the freshness lifetime of the resource expires.

> 
> If we don't, like WebKit (and Opera) doing now, once browser starts with network connection, it won't detect network connection loss, which happened not that common for a PC but common for a mobile device. And it will effectively defeat the intention of "fallback" resources in a offline web application, as the content for a "fallback namespace" from cache will be used, instead of the content of its mapping "fallback entry".

Clients have other ways to detect loss of connection:
(a) platform-specific APIs that track the state of network interfaces.
(b) Revalidating cached items once their freshness lifetime expires.

That being said, if you think there is a problem with the spec, you should report it to the W3C Web Apps WG or the WHATWG.

Regards,
Maciej

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