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Re: Producing Atom (was: Microdata vocabulary specifications)

From: Ian Hickson <ian@hixie.ch>
Date: Sun, 4 Oct 2009 21:15:10 +0000 (UTC)
To: Sam Ruby <rubys@intertwingly.net>
Cc: Julian Reschke <julian.reschke@gmx.de>, Maciej Stachowiak <mjs@apple.com>, public-html@w3.org
Message-ID: <Pine.LNX.4.62.0910042105240.3716@hixie.dreamhostps.com>
On Sun, 4 Oct 2009, Sam Ruby wrote:
> > 
> > (Incidentaly, a side-effect of this is that the HTML-to-Atom 
> > conversion algorithm can no longer output valid Atom. It used to rely 
> > on the vCard vocabulary to get the value of <author>, but this is no 
> > longer possible since there's no reference to the vocabulary specs.)
> 
> re: "no longer possible"... why not?

Atom requires an <author> element, but the only mechanism in HTML to 
specify an author's name as part of contact information would be to use 
Microdata (a vCard in an <address>). Since HTML5 hosts the Atom conversion 
algorithm but vCard is no longer in HTML5, I had to remove the part of the 
Atom conversion algorithm that referred to vCards, thus preventing the 
required <author> element(s) from being generated.


> In particular, what would be the harm in allowing conforming 
> implementations to add additional information as long as they continue 
> to provide all of the information required by the algorithm?

People might come to rely on the information added by particular vendors, 
at which point we effectively have changed the de-facto algorithm and 
would have to update the de-jure algorithm also, regardless of which specs 
that meant we had to reference.

But that's not particularly a big problem, at least not in my opinion. 
It's also not really relevant: the point isn't that it's not possible to 
have an HTML-to-Atom conversion that generates valid Atom (it obviously 
is, since HTML5 used to have such an algorithm); the point is that with 
the restriction that we can't reference the vCard algorithm from HTML5, 
the algorithm had to be changed in such a way that the output is no longer 
conforming by default.


> Furthermore, why couldn't additional specifications define additional 
> information to be placed into the feed?

They could, but that wouldn't change whether HTML5's algorithm alone 
produced conforming Atom.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Sunday, 4 October 2009 21:06:11 GMT

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