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Re: Link: relation registry and 303

From: Anne van Kesteren <annevk@opera.com>
Date: Tue, 03 Feb 2009 14:30:44 +0100
To: "Mark Nottingham" <mnot@mnot.net>, "Roy T. Fielding" <fielding@gbiv.com>
Cc: "www-tag@w3.org WG" <www-tag@w3.org>, "Henri Sivonen" <hsivonen@iki.fi>
Message-ID: <op.uor2hiof64w2qv@annevk-t60.oslo.opera.com>

On Sat, 31 Jan 2009 01:46:49 +0100, Mark Nottingham <mnot@mnot.net> wrote:
> On 31/01/2009, at 11:00 AM, Roy T. Fielding wrote:
>> HTML5 can just assume they are aliases.
>
> They had a problem with that; i.e., they didn't want to have to consider  
> all of the following as equivalent;
>
> [...]
>
> I've always been a bit skeptical of this argument, but those who were  
> discussing it at the time (this is in the archives, around the  
> November/December 2008 timeframe; e.g.,  
> <http://www.w3.org/mid/op.ulx1d6cx64w2qv@annevk-t60.oslo.opera.com >)  
> did seem to come to consensus. I've cc:ed a few of those folks to draw  
> their attention to this thread (Anne and Henri, see:  
> <http://www.w3.org/mid/906D6F3A-F031-4993-8F53-F48C9E14A622@mnot.net >  
> and the convoluted thread around it).

The problem is that the gain is pretty artificial. Introducing user agent  
complexity (having to resolve rel attribute values in addition to ASCII  
case-insensitively comparing them) and author complexity (learning that  
both are ok, but that the canonical one does not work in the most widely  
deployed browser) just does not seem worth it. There are more important  
issues to tackle. It would presumably also require changing various DOM  
APIs that expose these tokens conveniently to take into account URLness  
and it would create issues with existing values that do not match the  
syntax at all:

   http://philip.html5.org/data/link-rel-rev.txt


> HTML5 folks, if we were to move back to using URIs for all link  
> relations, specifying that they need to be case-normalised before  
> comparison, would that work for you, and if not, why? Is the  
> implementation cost of case normalisation + resolving against a base URI  
> really that high? Is there something I'm missing here?

I'm not that convinced of the usefulness of this feature. To be clear,  
HTML5 rel attribute values can be URIs, but they do not have to be and  
whether or not they are does not have any special significance with  
regards to existing values and APIs. I.e., author and user agent  
complexity is not increased.


-- 
Anne van Kesteren
<http://annevankesteren.nl/>
<http://www.opera.com/>
Received on Tuesday, 3 February 2009 13:31:45 GMT

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