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Re: Terminology Question concerning Web Architecture and LinkedData

From: Chris Bizer <chris@bizer.de>
Date: Wed, 11 Jul 2007 14:44:31 +0200
Message-ID: <003b01c7c3b9$3a7041f0$418d2da0@wrz03715>
To: <www-tag@w3.org>, <semantic-web@w3.org>, "Linking Open Data" <linking-open-data@simile.mit.edu>

Hi,

thanks a lot to everybody who helped answering my questions!

My take-aways from the answers so far are:

Question 1: According to the terminology of the Architecture of the 
WWW
document [4] are all these URIs aliases for the same non-information
resource (our current view) or are they referring to different 
resources?

Dan:
> They are aliases: the URI owners say so and nothing in webarch
> says otherwise.

Thanks a lot for reassuring us on this. This was critical for the 
tutorial.

Alan:
This is a question of what the publishers of those URI's say they mean 
to
denote by those URIs, or alternatively, what a community of users 
agrees these
URIs shall denote.

This nicely corresponds to Dan's answer to question 3 :-)

Question 2: What would be the correct Web Architecture term to refer 
to this concept?
Or is such a term missing?

Dan:
> I don't think the TAG has established a term for that.

Bernard:
>Is not such information called a "Description", with a "D" like in 
>RDF?

Yes, sometimes one gets confused by all this 303 redirecting and 
content-negotiation.
In the end it is just a description of a non-information resource 
(which is retrieved through some HTTP magic ;-)

Question 3: Is it correct to use owl:sameAs [6] to state that 
http://www.w3.org/People/Berners-Lee/card#i and
http://dbpedia.org/resource/Tim_Berners-Lee refer to the same thing as 
it is done in Tim's profile?

Dan:
> It's correct because Tim says it's correct, and he owns that name.

I like this answer as it clearly points at the Semantic Web being a 
social system where information providers express their opinions which 
can be right or wrong. Tim is stating that he thinks that both URIs 
refer to the same non-information resource. It is now up to the 
information consumer to decide if he likes to believe this statement 
or not.

Bernard:
> To put together the following URIs, you have set rules, or whatever
> heuristics, to discover that two URIs are "aliases" of the same
> non-information resource. And seems to me that those 
> rules/heuristics
> should be exposed explicitly. We are in the Linking Open Data 
> process.
> The data are open, so should be the rules used to link them. Open 
> means
> the rules are explicit and exposed, so that anyone can reproduce 
> their
> behaviour, and accept or not to play by those rules.

Yes, as in Dan's answer it comes down to the information consumer 
believing the owl:sameAs statements or not.
Which leads us to the classic Semantic Web trust (or the term I like 
better: information quality) problem. Making the rules explicit would 
be helpful for allowing the information consumer to decide whether to 
believe the statement or not.  Having this deployed as a best practice 
for information providers is way of in my opinion. But maybe another 
reason why RIF could be interesting ;-)

Thanks again :-)

Cheers

Chris

P.S. We hope to be able to circulate the first version of our tutorial 
next week.

--
Chris Bizer
Freie Universit├Ąt Berlin
Phone: +49 30 838 54057
Mail: chris@bizer.de
Web: www.bizer.de

----- Original Message ----- 
From: "Dan Connolly" <connolly@w3.org>
To: "Chris Bizer" <chris@bizer.de>
Cc: <www-tag@w3.org>; <semantic-web@w3.org>; "Linking Open Data" 
<linking-open-data@simile.mit.edu>
Sent: Tuesday, July 10, 2007 7:08 PM
Subject: Re: Terminology Question concerning Web Architecture and 
LinkedData


> On Sat, 2007-07-07 at 14:43 +0200, Chris Bizer wrote:
>> Hi all,
>>
>> Richard Cyganiak, Tom Heath and me are currently writing a tutorial 
>> on how
>> to publish Linked Data [1] on the Web and ran into some terminology
>> questions concerning Web Architecture.
>>
>> Here is the problem statement together with an example: Within the 
>> Linking
>> Open Data community project [2] different data sources (URI owners) 
>> publish
>> information about Tim Berners-Lee using different HTTP URIs:
>>
>> 1. DBpedia: http://dbpedia.org/resource/Tim_Berners-Lee
>> 2. Hannover DBLP Server:
>> http://dblp.l3s.de/d2r/resource/authors/Tim_Berners-Lee
>> 3. Berlin DBLP Server:
>> http://www4.wiwiss.fu-berlin.de/dblp/resource/person/100007
>> 4. RDF Book Mashup:
>> http://www4.wiwiss.fu-berlin.de/bookmashup/persons/Tim+Berners-Lee
>>
>> The first 3 data sources follow the W3C TAG "Dereferencing HTTP 
>> URIs"
>> finding [3]
>
> draft, in progress...
>
>>  and redirect via HTTP 303 to documents describing Tim
>> Berners-Lee when the URIs are dereferenced over the Web. Therefore, 
>> the URIs
>> identify Tim Berners-Lee as a non-information resource.
>
> Rather: therefore the do not claim that these URIs
> identify information resources.
>
> The lack of a claim is very different from the negation of a claim.
>
>>  This redirect also
>> supports HTTP content negotiation and leads to HTML as well as RDF
>> descriptions of Tim.
>>
>> 5. Tim also publishes a FOAF profile in which he assigns the URI
>> http://www.w3.org/People/Berners-Lee/card#i to himself.
>>
>> Question 1: According to the terminology of the Architecture of the 
>> WWW
>> document [4] are all these URIs aliases for the same 
>> non-information
>> resource (our current view) or are they referring to different 
>> resources?
>
> They are aliases: the URI owners say so and nothing in webarch
> says otherwise.
>
>> Does the TAG finding "On Linking Alternative Representations To 
>> Enable
>> Discovery And Publishing " [5] about generic and specific resources 
>> apply
>> here, meaning that the URIs 1,2,3,5 refer to different specific
>> non-information resources that are related to one generic 
>> non-information
>> resource?
>
> No, I don't think so.
>
> The generic resource finding is mostly about information resources, 
> I
> think.
>
>> Question 2: When the URIs are dreferenced they provide quite 
>> different
>> information about Tim, which reflects the knowledge and the opinion 
>> of the
>> specific URI owner about him. Within our tutorial we need to talk 
>> about this
>> information and therefore need a term to refer to a concept that 
>> can be
>> described as "information provided by a specific URI owner about a
>> non-information resource", for example Tim. Depending on the answer 
>> to
>> question 1, what would be the correct Web Architecture term to 
>> refer to this
>> concept? Or is such a term missing?
>
> I don't think the TAG has established a term for that.
>
> (It sounds a bit like log:semantics from N3, but I'm not quite sure
> http://www.w3.org/2000/10/swap/doc/Reach )
>
>> Question 3: Depending on the answer to question 1, is it correct to 
>> use
>> owl:sameAs [6] to state that 
>> http://www.w3.org/People/Berners-Lee/card#i and
>> http://dbpedia.org/resource/Tim_Berners-Lee refer to the same thing 
>> as it is
>> done in Tim's profile.
>
> Yes...
>
> That's sort of a circular question. It's correct because Tim says
> it's correct, and he owns that name.
>
>> Any clarifications on these question would be highly welcomed.
>>
>> Cheers
>>
>> Chris
>>
>>
>> [1] http://www.w3.org/DesignIssues/LinkedData.html
>> [2]
>> http://esw.w3.org/topic/SweoIG/TaskForces/CommunityProjects/LinkingOpenData
>> [3] 
>> http://www.w3.org/2001/tag/doc/httpRange-14/2007-05-31/HttpRange-14
>> [4] http://www.w3.org/TR/webarch/
>> [5] http://www.w3.org/2001/tag/doc/alternatives-discovery.html
>> [6] http://www.w3.org/TR/owl-ref/#sameAs-def
>>
>> --
>> Chris Bizer
>> Freie Universit├Ąt Berlin
>> +49 30 838 54057
>> chris@bizer.de
>> www.bizer.de
>>
> -- 
> Dan Connolly, W3C http://www.w3.org/People/Connolly/
>
> 
Received on Wednesday, 11 July 2007 12:48:36 GMT

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