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Re: Cool URIs, the Semantic Web and Everything

From: Richard Cyganiak <richard@cyganiak.de>
Date: Fri, 28 Dec 2007 14:21:45 +0100
Cc: "Hausenblas, Michael" <michael.hausenblas@joanneum.at>, Leo Sauermann <sauermann@dfki.uni-kl.de>, semantic-web@w3.org
Message-Id: <D5C350C2-E110-4672-926D-28373DAAA4B7@cyganiak.de>
To: Leo Sauermann <leo.sauermann@dfki.de>


On 25 Dec 2007, at 21:41, Leo Sauermann wrote:
[snip]
>>> Q.II:  What does http://sw-app.org/mic.xhtml#i identfiy?
[snip]
>> 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.
>>
> I don't know about removing the ID, maybe this would be good. But I  
> would not make a "must" out of it, why not keep both

The application/xhtml+xml MIME type registration says: If there is  
@id="i" in the XHTML document, then <mic.xhtml#i> designates a part of  
that document. Thus, web architecture clearly states that  
<mic.xhtml#i> identifies a document part.

Michael's RDFa, however, says that <mic.xhtml#i> denotes a person.

That's a contradiction. A person is not a section of a document.  
Therefore, the @id="i" *MUST* be changed or removed, otherwise we have  
a URI collision.

Richard



>
>
> best
> Leo
>
>>
>>
>>>
>>>
>>>
>>> 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/
>>>>>>            
>>>>>> ----------------------------------------------------------
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>
>
> -- 
> ____________________________________________________
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> ____________________________________________________
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>
Received on Friday, 28 December 2007 13:22:06 GMT

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