W3C home > Mailing lists > Public > semantic-web@w3.org > December 2007

Re: Cool URIs, the Semantic Web and Everything

From: Richard Cyganiak <richard@cyganiak.de>
Date: Mon, 24 Dec 2007 00:05:14 +0000
Cc: Michael Hausenblas <michael.hausenblas@joanneum.at>, Leo Sauermann <sauermann@dfki.uni-kl.de>, SW-forum Web <semantic-web@w3.org>
Message-Id: <C85BA457-8569-463A-9FD1-A3D2F30809F4@cyganiak.de>
To: Story Henry <henry.story@bblfish.net>

On 23 Dec 2007, at 22:31, Story Henry wrote:

> Why does id="i" have to refer to anything?

Well, the specs say so. The URI spec says that the meaning of hashy  
URIs depends on the MIME type of what you GET, and that each MIME type  
registration must say what hashes mean in that type. The XHTML  
registration says that #xyz designates the document part that has  
id="xyz". There you have it, that's the status quo. And I think it's a  
decent state of affairs.

> Why is it not just a behavioral specification that when displaying  
> html the page be move to that location if something like that is  
> present?

To my knowledge, associating "behavioral specifications" with URIs is  
a new idea not currently found in web architecture. The current  
architecture seems to take the point of view that URI simply  
"identify" certain things; associating appropriate behaviour with  
those things is up to applications. I think that's a decent state of  

> That would allow one to have a
> <http://sw-app.org/mic.xhtml#i> refer to a person, and also to have  
> an xhtml web page be showing the relevant part of the information.
> I am not sure the two need to be exclusive.

I agree, it's desirable that an RDFa URI <mic.xhtml#i>, if accessed in  
a web browser, automatically scrolls to the relevant part of the  

But there are many ways to achieve that goal. Some good, some bad.

Adding id="i" to the document is a bad way, because it overloads the  
meaning of <mic.xhtml#i>.

Future RDFa-aware browsers could natively support this, by scrolling  
to the part of the document that carries the RDFa specification of the  
URI (e.g. an about="#i" attribute).

In the meantime, we could add a generic Javascript snippet to the  
document that automatically scrolls to id="definition_xyz" when #xyz  
is opened. This gives us the desired behaviour, while retaining  
different URIs for person and document section. (Yes, it's a hack.)

Merry Christmas to all!


> Henry
> On 23 Dec 2007, at 13:25, Richard Cyganiak wrote:
>> This is impossible to answer, because the URI's configuration is  
>> broken. Even the author of the document seems to be confused about  
>> what he wants the URI to identify.
>> There is an XHTML representation, and it has a id="i", which  
>> indicates that the URI identifies an XHTML fragment.
>> But the XHTML document also encodes an RDF graph using RDFa. In it,  
>> the author tries to use the same URI to denote a person. He claims  
>> that a document fragment is a person. That's a nonsensical statement.
>> Fortunately, this is easy to fix: Remove the id="i" from the  
>> document, or change it to a different ID, and everything is fine.  
>> After that fix, the answer would be 1, 2 and 6.
>> Richard
Received on Monday, 24 December 2007 00:05:22 UTC

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