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Re: [httpRange-14] Conneg and Acceptable HTTP Variants

From: Dan Brickley <danbri@danbri.org>
Date: Sat, 15 Dec 2007 20:21:51 +0000
Message-ID: <4764375F.5040100@danbri.org>
To: Tim Berners-Lee <timbl@w3.org>
CC: "Sean B. Palmer" <sean@miscoranda.com>, www-tag@w3.org

Tim Berners-Lee wrote:
> 
> Exactly.
> Tim
> 
> On 2007-12 -15, at 12:56, Sean B. Palmer wrote:
> 
>>
>> Tim gave us a rule of thumb about what kind of HTTP variants it's
>> acceptable to conneg between which caused some controversy:
>>
>> "When people conneg between HTML and RDF, the HTML is
>> generated from the RDF. Else it is a bug." - TimBL, in [1]
>>
>> Dan Brickley was the first to cry wolf about this, asking how an
>> acceptable level of degradation is defined. Kjetil Kjernsmo asked
>> about a specific use case, of an RDF FOAF file generated from RDFa or
>> GRDDL.
>>
>> What most of you may not have seen is that TimBL later gave Kjetil a
>> very useful answer [2], which I repeat here:
>>
>> <timbl> kjetilkWork, re http://www.ski-o.com/user/kjetil you could
>> offer both. Which would you want a person to see who is using
>> FFox+Tabulator extension?

A cheap shot perhaps, but since you mention it: not everyone can see. To 
some, an SVG version of an image resource might be lossy (as a cartoon 
vs a photo); to others, it might be vastly richer (eg. see [1]). There's 
no intrinsic quality ordering: brevity might be best, for someone on an 
expensive GPRS connection (eg. me, yesterday --- I spent 5GBP in a 
mature of minutes trying to get online via my phone).

If you don't want to be presented with the application/rdf+xml flavour 
of a document, perhaps it's best not to configure your browser to ask 
for it? That said, I've not tried the FF Tabulator addon yet, I'll give 
it a go.

[...]

OK, my Firefox is now Tabulator-enriched. And the FOAF spec looks ... 
even more cryptic than normal! Especially if I go to a link that has a # 
in it, eg http://xmlns.com/foaf/spec/#term_openid ... resulting UI is 
utterly baffling, but strangely evocative :)  The interface I get if I 
visit http://xmlns.com/foaf/spec/ is much less confusing (rather handy 
in fact), ... but I don't understand why Firefox couldn't generate it 
for me as a sidebar to the main HTML document. A super-smart semantic 
browser ought to be able to figure out that an HTML version is 
available, and have some way of presenting it to me.

But back to the main point, I'm not defending CONNEG as a perfect 
technology. It's missing all kinds of things, esp around discovery. But 
I don't see the "some variants are unacceptably lossy" argument as 
persuasive.

cheers,

[1] http://www.w3.org/TR/SVG-access/
Received on Saturday, 15 December 2007 20:22:02 GMT

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