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Re: two failings of XLink

From: Elliotte Rusty Harold <elharo@metalab.unc.edu>
Date: Fri, 27 Sep 2002 09:00:37 -0400
Message-Id: <p04330102b9ba04f06b78@[192.168.254.4]>
To: Micah Dubinko <MDubinko@cardiff.com>, "'www-tag@w3.org'" <www-tag@w3.org>

At 11:08 PM -0700 9/26/02, Micah Dubinko wrote:

>So let's agree that either there is a DTD or Schema present to provide
>default attributes (which would be a significant change to XHTML), or that
>the hypothetical spec under discussion does some hand-waving to the same
>effect.

XHTML *always* has a DTD. If it doesn't, then it's not conforming 
XHTML. This is true in XHTML 1.0, XHTML 1.1, and presumably XHTML 
2.0. Indeed, including SGML DTDs, all HTML documents have DTDs (even 
if the documents are not valid and the DTDs are not specified in a 
document type declaration.) This is absolutely nothing new.

>The default attributes added could be either simple or extended. Let's look
>at both.
>
>Elimination 2: Simple XLink. If the DTD provided xlink:type="simple"
>defaults on the first three child elements, this would, in XLink 1.0 terms,
>define three separate, unrelated links:
><longdesc> -> http://www.example.com
><src> -> http://www.example.org
><someotherlink> -> http://www.example.net
>And still, none of the links consider, in XLink 1.0 terms, <object> to be
>involved.

I don't care about XLink 1.0 terms.  I care about XHTML terms. If 
XHTML decides to do this. XHTML can, and it can do so completely 
within the confines of XLink.

>It would be disrespectful to XLink, IMHO, to bless such an incorrect usage
>pattern. A mythical generic XLink processor (say a link harvester, or a
>stylesheet, or a spider) would be totally misled into believing that there
>were three unrelated links, when this is really a single link with multiple
>ends.

I disagree. The XLink spec states "If a simple-type element contains 
nested XLink elements, such contained elements have no 
XLink-specified relationship to the parent link." This is in no way 
rules out containing and contained elements from having relationships 
to each other defined outside of XLink.

As to the link harvester, you're putting the cart before the horse. 
Link harvesters know a lot more about HTML than XLinks. I do not find 
it the least bit improbable that XLink harvesters will know and 
understand the relationships of XHTML link usages, whatever form that 
eventually takes.
-- 

+-----------------------+------------------------+-------------------+
| Elliotte Rusty Harold | elharo@metalab.unc.edu | Writer/Programmer |
+-----------------------+------------------------+-------------------+
|          XML in a  Nutshell, 2nd Edition (O'Reilly, 2002)          |
|              http://www.cafeconleche.org/books/xian2/              |
|  http://www.amazon.com/exec/obidos/ISBN%3D0596002920/cafeaulaitA/  |
+----------------------------------+---------------------------------+
|  Read Cafe au Lait for Java News:  http://www.cafeaulait.org/      |
|  Read Cafe con Leche for XML News: http://www.cafeconleche.org/    |
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Received on Friday, 27 September 2002 09:11:21 GMT

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