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Re: Pre-fetch rough draft

From: Charles McCathie Nevile <chaals@yandex-team.ru>
Date: Mon, 05 Nov 2012 19:31:30 +0100
To: "Julian Reschke" <julian.reschke@gmx.de>
Cc: "Michael Nordman" <michaeln@google.com>, "public-webapps WG" <public-webapps@w3.org>
Message-ID: <op.wnbcess2y3oazb@any.yandex.ru>
On Mon, 05 Nov 2012 13:28:43 +0100, Julian Reschke <julian.reschke@gmx.de>  
wrote:

> On 2012-11-02 11:16, nop@yandex-team.ru wrote:
>>> On Tue, 30 Oct 2012, Michael Nordman <michaeln@google.com> wrote
>>>
>>> The appcache is encumbered with guarantees about atomically updating a  
>>> set of resources and then explicitly not hitting the network for them
...
>>> This gist of this prefetch list seems different. More of a hint to warm
>>> things up if possible and viola things are more responsive if those  
>>> hints are taken.
>>>
>>
>> Yes. Exactly.
>> It's not about offline apps, it's about reducing loading time.
>
> There's already the "prefetch" link relation that you could use.

This makes sense if we agree that prefetching a manifest (see below for  
some reasons I think they serve different initial use cases) is the same  
as prefetching an individual resource. Personally I am not convinced that  
is true, although I don't know of any reason to feel strongly one way or  
the other.

>> Prefetch manifest is a way to tell browser what should be downloaded in  
>> advance. So when user opens the site (for the first time) all resources  
>> (css/js/images/...) are already cached.
>>
>> And if later site's resources are updated browser could check prefest  
>> manifest and re-download all new resources in background. Before user
>> visited site again.
>
> But then you don't need a manifest for that (see above).

I think you do in the case where the list of resources that are used by  
the site changes faster than the resources themselves.

e.g.
1. We use several versions of a script library, because different sites  
that rely on them update at different times. So we might point to v 1.1.1  
and v 1.1.2 and v 1.2.1 in different Yandex properties, updating the  
prefetch manifest while the cache-control says we're not changing the  
version-specific stuff.
2. We highlight some photos in a property. The photos are static resources  
- but the highlights change every so often (but not every page view or  
there would be no point in caching).

cheers

Chaals

-- 
Charles McCathie Nevile - Consultant (web standards) CTO Office, Yandex
       chaals@yandex-team.ru         Find more at http://yandex.com
Received on Monday, 5 November 2012 18:32:12 GMT

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