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Re: recommend Accept in preference to User-Agent to determine formats

From: Charles McCathieNevile <chaals@opera.com>
Date: Tue, 12 Dec 2006 10:35:08 +0530
To: "Dan Connolly" <connolly@w3.org>, public-bpwg-comments@w3.org
Message-ID: <op.tkfkeumqwxe0ny@widsith.local>

On Wed, 29 Nov 2006 14:59:01 +0530, Dan Connolly <connolly@w3.org> wrote:

> Regarding...
> "To determine what formats a device supports, Web sites may use any
> combination of device profile information such as the HTTP User-Agent
> header, HTTP Accept headers and UAProf."
>  -- http://www.w3.org/TR/mobile-bp/ (2 November 2006)
> The HTTP accept header is specifically designed for this purpose;
> web sites SHOULD use it.

The problem is, given the cost (in terms of battery consumption, latency,  
bandwidth, ...) of sending data from a device, it makes no sense at all  
for reasonably capable devices to be sending the 1kb or so of data that  
would make this feasible.

> It's OK to say that they MAY use other stuff, but it doesn't
> make sense to say that User-Agent is just as good as Accept
> for figuring out what format the client wants.

In practical terms it does. The standard might say otherwise, but  
unfortunately there are real problems engendered in actually implementing  
it, which is why browsers don't (as far as I know the only browsers that  
are accurate are those which only accept a couple of formats anyway, and  
Lynx which sends a monstrous amount of data).



   Charles McCathieNevile, Opera Software: Standards Group
   hablo español  -  je parle français  -  jeg lærer norsk
chaals@opera.com          Try Opera 9 now! http://opera.com
Received on Tuesday, 12 December 2006 05:05:24 UTC

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