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Re: Cool URIs, the Semantic Web and Everything

From: Richard Cyganiak <richard@cyganiak.de>
Date: Sun, 23 Dec 2007 15:25:05 +0000
Cc: "Leo Sauermann" <sauermann@dfki.uni-kl.de>, <semantic-web@w3.org>, "Leo Sauermann" <leo.sauermann@dfki.de>
Message-Id: <0E90798D-926D-43B1-9B08-5C59B51DEF18@cyganiak.de>
To: "Hausenblas, Michael" <michael.hausenblas@joanneum.at>


On 23 Dec 2007, at 08:22, Hausenblas, Michael wrote:
> Although feeling uncomfortable being labelled as the 'complainant' :)

As an author, I know that every work of interest will draw some  
complaints, some justified and some not. And I prefer a clearly voiced  
complaint over nebulous expressions of doubt. Therefore, when you see  
room for improvement, please complain loudly and clearly ;-)

> I guess that this wording would improve the text.
>
> Now, due to X-mas approaching, let's relax and quiz a bit
> (multiple choice):
>
>
> Q.I: What is http://sw-app.org/mic.xhtml#i?
>
> 1. A URI
> 2. A URL
> 3. A foaf:Person
> 4. Michael Hausenblas
> 6. An XHTML fragment

It's a URI.

> Q.II:  What does http://sw-app.org/mic.xhtml#i identfiy?
>
> 1. A foaf:Person
> 2. Michael Hausenblas
> 4. An XHTML fragment
> 5. Depends on who looks at it: A Web UA 'sees' a XHTML fragment,
>   a SW agent a thing of type foaf:Person
> 6. Dunno until I do an HTTP GET

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


>
>
>
> Cheers,
> 	Michael
>
> ----------------------------------------------------------
> Michael Hausenblas, MSc.
> Institute of Information Systems & Information Management
> JOANNEUM RESEARCH Forschungsgesellschaft mbH
> Steyrergasse 17, A-8010 Graz, AUSTRIA
> ----------------------------------------------------------
>
>> -----Original Message-----
>> From: Richard Cyganiak [mailto:richard@cyganiak.de]
>> Sent: Friday, December 21, 2007 5:26 PM
>> To: Hausenblas, Michael
>> Cc: Leo Sauermann; semantic-web@w3.org; Leo Sauermann
>> Subject: Re: Cool URIs, the Semantic Web and Everything
>>
>> Michael,
>>
>> On 21 Dec 2007, at 08:23, Hausenblas, Michael wrote:
>>> In Cool URIs you are
>>> referring to a certain
>>> setup ('deployment scenarios in which the RDF data and the
>> HTML data
>>> is served separately').
>>> Also the figure right before section 3.1 suggests that there is an
>>> explicit RDF document and an HTML document, each with a
>> distinct URL.
>>> As you know, this is not the case with RDFa.
>>
>> Would changing the sentence
>>
>> "In those cases [RDFa, microformats and GRDDL] the RDF data
>> is extracted from the returned HTML document."
>>
>> to
>>
>> "In those cases, the RDF data is extracted from the HTML
>> document and no separate RDF document is needed."
>>
>> address your complaint?
>>
>> The rest of the document's narrative is consistent with use
>> of RDFa, as far as I can tell.
>>
>> Best,
>> Richard
>>
>>
>>>
>>>
>>> So, that is were my confusion stems from. I know that due to time
>>> constraints you decided that this is the way it is. It
>> would still be
>>> nice to learn why the figure right before section 3.1
>> (sorry, no label
>>> available) 'shows the desired relationships between a
>> resource and its
>>> describing documents'.
>>>
>>> Cheers,
>>> 	Michael
>>>
>>> [1]
>> http://lists.w3.org/Archives/Public/semantic-web/2007Dec/0121.html
>>>
>>> ----------------------------------------------------------
>>> Michael Hausenblas, MSc.
>>> Institute of Information Systems & Information Management JOANNEUM
>>> RESEARCH Forschungsgesellschaft mbH
>>>
>>> http://www.joanneum.at/iis/
>>> ----------------------------------------------------------
>>>
>>>
>>>> -----Original Message-----
>>>> From: Leo Sauermann [mailto:sauermann@dfki.uni-kl.de]
>>>> Sent: Thursday, December 20, 2007 12:36 PM
>>>> To: Hausenblas, Michael
>>>> Cc: semantic-web@w3.org; Leo Sauermann
>>>> Subject: Re: Cool URIs, the Semantic Web and Everything
>>>>
>>>> Hausenblas, Michael schrieb:
>>>>
>>>> 	Leo,
>>>> 	
>>>> 	Thanks for your explanation. I remain not totally convinced :)
>>>> 	
>>>>
>>>> good, then give a practical example (using concrete RDFa
>> code) where
>>>> you think some work needs to be done and provide a
>> suggestion how to
>>>> solve it. That you are not convinced may be caused by
>> various reasons
>>>> we don't know about, shine light on them.
>>>>
>>>>
>>>>
>>>> 	
>>>> 	So, *if* we agree on what you said, IMHO we should
>>>> 	reconsider the following paragraph in 'Cool URIs' [1]:
>>>> 	
>>>> 	'The solutions described in the following apply to deployment
>>>> scenarios
>>>> 	in which the RDF data and the HTML data is served
>> separately, such
>>>> as a
>>>> 	standalone RDF/XML document
>>>> 	along with an HTML document. The metadata can also be
>> embedded in
>>>> HTML,
>>>> 	using technologies such as
>>>> 	RDFa [RDFa Primer], microformats and other documents to
>> which the
>>>> GRDDL
>>>> 	[GRDDL] mechanisms can be applied.
>>>> 	In those cases the RDF data is extracted from the returned HTML
>>>> 	document.'
>>>> 	
>>>>
>>>> I see no reason for changes until you exactly specify where this
>>>> paragraph contradicts http-range-14 or other TAG
>> resolutions or W3C
>>>> recommendations.
>>>>
>>>> the point is that RDF/XML, N3, RDFa and GRDDL are
>> mimetypes encoding
>>>> RDF triples while URIs are something used inside these RDF
>> triples,
>>>> so at the beginning both are completly different and do not affect
>>>> each other.
>>>>
>>>> "Cool uris" is about URIs and not about RDF serialization.
>>>>
>>>> best
>>>> Leo
>>>>
>>>>
>>>>
>>>> 	
>>>> 	Still unsure if this is just the tip of the iceberg ...
>>>> 	
>>>>
>>>> 	
>>>> 	Cheers,
>>>> 		Michael
>>>> 	
>>>> 	[1] http://www.w3.org/TR/2007/WD-cooluris-20071217/#solutions
>>>> 	
>>>> 	----------------------------------------------------------
>>>> 	 Michael Hausenblas, MSc.
>>>> 	 Institute of Information Systems & Information Management
>>>> 	 JOANNEUM RESEARCH Forschungsgesellschaft mbH
>>>> 	
>>>> 	 http://www.joanneum.at/iis/
>>>> 	----------------------------------------------------------
>>>> 	
>>>> 	
>>>> 	
>>>>
>>>> 		-----Original Message-----
>>>> 		From: Leo Sauermann [mailto:sauermann@dfki.uni-kl.de]
>>>> 		Sent: Thursday, December 20, 2007 3:43 AM
>>>> 		To: Hausenblas, Michael
>>>> 		Cc: semantic-web@w3.org; Leo Sauermann
>>>> 		Subject: Re: Cool URIs, the Semantic Web and Everything
>>>> 		
>>>> 		Hi Michael, RDFa people,
>>>> 		
>>>> 		The question is if httpRange-14 [2] is valid in
>> the case of
>>>> XHTML+RDFa.
>>>> 		
>>>> 		The answer is that httpRange-14 is to
>> distinguish URIs for
>>>> information
>>>> 		resources ("web documents") from real-world
>> objects (the person
>>>> 		"Alice"). As such, it is a recommendation on URIs.
>>>> 		
>>>> 		RDFa is an encoding of RDF, and typically an
>> RDFa document has two
>>>> 		relations to URIs:
>>>> 		a) the URI of the RDFa document (=the
>> information resource where I
>>>> can
>>>> 		download the RDFa document)
>>>> 		b) the URIs used as subjects, predicates,
>> objects inside RDF
>>>> 		statements
>>>> 		written inside RDFa documents
>>>> 		
>>>> 		a) is usually a http-200 uri, and a) is an
>> information resource (=
>>>> a
>>>> 		document).
>>>> 		In the rdf statemetns written inside  A, you
>> would use both URIs
>>>> for
>>>> 		real-world objects and information resources.
>>>> 		example (I don't know  rdfa syntax by heart
>> now, assume this is
>>>> rdfa):
>>>> 		
>>>> 		document at www.example.com/homepage/aboutAlice
>>>> 		<html>
>>>> 		<p
>>>> rdf:about="http://www.example.com/identifiers/alice#this"
>>>> <http://www.example.com/identifiers/alice#this> >
>>>> 		 rdf:type foaf:Person.
>>>> 		</p>
>>>> 		<p
>>>> rdf:about="http://www.example.com/moreidentifiersusing303/bob"
>>>> <http://www.example.com/moreidentifiersusing303/bob> >
>>>> 		rdf:type foaf:Person
>>>> 		</p>
>>>> 		</html>
>>>> 		
>>>> 		assuming this would be valid RDFa, the URI
>> .../aboutAlice is a
>>>> 		http-return-200 informaiton resource
>>>> 		.../alice#this is a real-world object as it is
>> not a document (as I
>>>> 		understand timbl on that)
>>>> 		...303/bob is not intuitively distinguishable -
>> if you ignore the
>>>> 		rdf:type relation you don't know what it is. So
>> for this uri you do
>>>> a
>>>> 		HTTP get and the server would return a 303
>> redirect as described in
>>>> 		"cool uris".
>>>> 		once oyu did the 303, you knowthat ....303/bob
>> is a real world
>>>> object.
>>>> 		
>>>> 		so RDFa and 303'/httprange14 are
>>>> recommendations caring about
>>>> 		different
>>>> 		angles, 303 is only concerned about URIs, RDFa
>> about an RDF
>>>> 		serialization. Technically they don't interfere.
>>>> 		
>>>> 		If I would use RDFa much and would like cool
>> uris, I would go for
>>>> 		#-uris, they are simple to use and easy to
>> embed in RDFa.
>>>> 		but as shown above, you can use any URI you
>> want inside rdfa.
>>>> 		
>>>> 		best
>>>> 		Leo
>>>> 		
>>>> 		
>>>> 		Hausenblas, Michael schrieb:
>>>> 		
>>>>
>>>> 			===
>>>> 			Disclaimer: Michael, with his
>>>> RDFa-Task-Force-member hat off ;)
>>>> 			===
>>>> 			
>>>> 			As I gathered "Cool URIs for the
>>>> Semantic Web" is a Working
>>>> 			
>>>>
>>>> 		Draft, now.
>>>> 		
>>>>
>>>> 			Congrats to Leo and his team, great job!
>>>> 			
>>>> 			The following might sound like a naive
>> question - and I might
>>>> 			have missed something :) - but: Is TAG
>> finding httpRange-14 [2]
>>>> 			equally valid in the case of XHTML+RDFa?
>>>> 			
>>>> 			I've put together some initial thoughts
>> at the ESWiki [3]
>>>> 			- any comments welcome!
>>>> 			
>>>> 			Cheers,
>>>> 				Michael
>>>> 			
>>>> 			[1]
>>>> 			
>>>>
>>>> 		
>>>> http://lists.w3.org/Archives/Public/public-swd-wg/2007Dec/0103.html
>>>> 		
>>>>
>>>> 			[2]
>>>> http://www.w3.org/2001/tag/issues.html#httpRange-14
>>>> 			[3] http://esw.w3.org/topic/RDFa_vs_RDFXML
>>>> 			
>>>> 			
>>>> ----------------------------------------------------------
>>>> 			 Michael Hausenblas, MSc.
>>>> 			 Institute of Information Systems &
>> Information Management
>>>> 			 JOANNEUM RESEARCH Forschungsgesellschaft mbH
>>>> 			 Steyrergasse 17, A-8010 Graz, AUSTRIA
>>>> 			
>>>> 			 <office>
>>>> 			    phone: +43-316-876-1193 (fax:-1191)
>>>> 			   e-mail: michael.hausenblas@joanneum.at
>>>> 			      web: http://www.joanneum.at/iis/
>>>> 			
>>>> 			 <private>
>>>> 			   mobile: +43-660-7621761
>>>> 			      web: http://www.sw-app.org/
>>>> 			
>>>> ----------------------------------------------------------
>>>> 			
>>>> 			
>>>> 			
>>>>
>>>> 		
>>>> 		
>>>>
>>>> 	
>>>> 	
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>
Received on Sunday, 23 December 2007 15:25:21 GMT

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