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

Re: Cool URIs, the Semantic Web and Everything

From: Leo Sauermann <leo.sauermann@dfki.de>
Date: Sat, 29 Dec 2007 22:41:41 +0100
Message-ID: <4776BF15.4090002@dfki.de>
To: Richard Cyganiak <richard@cyganiak.de>
CC: "Hausenblas, Michael" <michael.hausenblas@joanneum.at>, Leo Sauermann <sauermann@dfki.uni-kl.de>, semantic-web@w3.org

Hi all,

It was Richard Cyganiak who said at the right time 28.12.2007 14:21 the 
following words:
>
> 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.
q.e.d. : Ok, I agree with that. Richard, that was a good resarch, thank you!
Michael: seems you must change your document! see also Ivan's answer 
before about <... about="i" ....>

best
Leo

>
> 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/
>>>>>>>           
>>>>>>> ----------------------------------------------------------
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>>
>> -- 
>> ____________________________________________________
>> DI Leo Sauermann       http://www.dfki.de/~sauermann
>> Deutsches Forschungszentrum fuer Kuenstliche Intelligenz DFKI GmbH
>> Trippstadter Strasse 122
>> P.O. Box 2080           Fon:   +49 631 20575-116
>> D-67663 Kaiserslautern  Fax:   +49 631 20575-102
>> Germany                 Mail:  leo.sauermann@dfki.de
>>
>> Geschaeftsfuehrung:
>> Prof.Dr.Dr.h.c.mult. Wolfgang Wahlster (Vorsitzender)
>> Dr. Walter Olthoff
>> Vorsitzender des Aufsichtsrats:
>> Prof. Dr. h.c. Hans A. Aukes
>> Amtsgericht Kaiserslautern, HRB 2313
>> ____________________________________________________
>>
>>
>


-- 
____________________________________________________
DI Leo Sauermann       http://www.dfki.de/~sauermann 

Deutsches Forschungszentrum fuer 
Kuenstliche Intelligenz DFKI GmbH
Trippstadter Strasse 122
P.O. Box 2080           Fon:   +49 631 20575-116
D-67663 Kaiserslautern  Fax:   +49 631 20575-102
Germany                 Mail:  leo.sauermann@dfki.de

Geschaeftsfuehrung:
Prof.Dr.Dr.h.c.mult. Wolfgang Wahlster (Vorsitzender)
Dr. Walter Olthoff
Vorsitzender des Aufsichtsrats:
Prof. Dr. h.c. Hans A. Aukes
Amtsgericht Kaiserslautern, HRB 2313
____________________________________________________
Received on Saturday, 29 December 2007 21:41:59 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 21:45:19 GMT