[whatwg] Application Cache for on-line sites

Fri Feb 11 15:03:51 PST 2011

bcc chromium-html5

In addition to what Michael has cited, I've had many developers (at various
Google events) ask why we don't have some API like this as well.  I think
it's clear there's demand.

On Fri, Feb 11, 2011 at 1:14 PM, Michael Nordman <michaeln at google.com>wrote:

> Waking this feature request up again as it's been requested multiple
> times, I think the ability to utilize an appcache w/o having to have
> the page added to it is the #1 appcache feature request that I've
> heard.
>
> * The Gmail mobile team has mentioned this.
>
> * Here's a thread on a chromium.org mailing list where this feature is
> requested: "How to instruct the main page to be not cached?"
>
> https://groups.google.com/a/chromium.org/group/chromium-html5/browse_thread/thread/a254e2090510db39/916f3a8da40e34f8
>
> * More recently this has been requested in the context of an
> application that uses pushState to alter the url of the main page.
>
> To keep this discussion distinct from others, I'm pulling in the few
> comments that have been made on another thread.
>
> hixie said...
> > Why can't the pages just switch to a more AJAX-like model rather than
> > having the main page still load over the network? The main page loading
> > over the network is a big part of the page being slow.
>
> and i replied...
> > The premise of the feature request is that the "main" pages aren't
> > cached at all.
> >
> > | I tried to use the HTML5 Application Cache to improve the performances
> > | of on-line sites (all the tutorials on the web write only about usage
> > | with off-line apps)
> >
> > As for "why can't the pages just switch", I can't speak for andrea,
> > but i can guess that a redesign of that nature was out of scope and/or
> > would conflict with other requirements around how the url address
> > space of the app is defined.
>
> Once you get past the "should this be a feature" question, there are
> some questions to answer.
>
> 1) How does an author indicate which pages should be added to the
> cache and which should not?
>
> A few ideas...
> a. <html useManifest='x'>
> b. If the main resource has a "no-store" header, don't add it to the
> cache, but do associate the document with the cache.
> b. A new manifest section to define a prefix matched namespace for these
> pages.
>
> 2) What sequence of events does a page that just uses the cache w/o
> being added to it observe?
>
> 3) At what point do subresources in an existing appcache start getting
> utlized by such pages? What if the appcache is stale? Do subresource
> loads cause revalidation?
>
> On Mon, Dec 20, 2010 at 12:56 PM, Michael Nordman <michaeln at chromium.org>
> wrote:
> > This type of request (see forwarded message below) to utilize the
> > application cache for subresource loads into documents that are not
> stored
> > in the cache has come up several times now. The current feature set is
> very
> > focused on the "offline" use case. Is it worth making additions such that
> a
> > document that loads from a server can utilize the resources in an
> appcache?
> > Today we have <html manifest="manifestFile">, which adds the document
> > containing this tag to the appcache and associates that doc with that
> > appcache such that subresource loads hit the appcache.
> > Not a complete proposal, but...
> > What if we had something along the lines of <html
> > useManifest=''manifestFile">, which would do the association of the doc
> with
> > the appcache (so subresources loads hit the cache) but not add the
> document
> > to the cache?
> >
> > ---------- Forwarded message ----------
> > From: UVL <andrea.doimo at gmail.com>
> > Date: Sun, Dec 19, 2010 at 1:35 PM
> > Subject: [chromium-html5] Application Cache for on-line sites
> > To: Chromium HTML5 <chromium-html5 at chromium.org>
> >
> >
> > I tried to use the HTML5 Application Cache to improve the performances
> > of on-line sites (all the tutorials on the web write only about usage
> > with off-line apps)
> >
> > I created the manifest listing all the js, css and images, and the
> > performances were really exciting, until I found that even the page
> > HTML was cached, despite it was not listed in the manifest. The pages
> > of the site are in PHP, so I don't want them to be cached.
> >
> > From
> > http://www.whatwg.org/specs/web-apps/current-work/multipage/offline.html
> > :
> > "Authors are encouraged to include the main page in the manifest also,
> > but in practice the page that referenced the manifest is automatically
> > cached even if it isn't explicitly mentioned."
> >
> > Is there a way to have this automating caching disabled?
> >
> > Note: I know that caching can be controlled via HTTP headers, but I
> > just wanted to try this way as it looks quite reliable, clean and
> > powerful.
> >
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