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Re: Granular dereferencing ( prop by prop ) using REST + LinkedData; Ideas?

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Sun, 04 Jan 2009 12:46:30 -0500
Message-ID: <4960F5F6.1020508@openlinksw.com>
To: Yves Raimond <yves.raimond@gmail.com>
CC: Richard Cyganiak <richard@cyganiak.de>, Aldo Bucchi <aldo.bucchi@gmail.com>, "public-lod@w3.org" <public-lod@w3.org>

On 1/4/09 9:28 AM, Yves Raimond wrote:
>
> Hi Richard!
>
> On 3 Jan 2009, at 12:23, Richard Cyganiak <richard@cyganiak.de> wrote:
>
>>
>> On 2 Jan 2009, at 23:20, Yves Raimond wrote:
>> <snip>
>>>> I proposed this solution:
>>>> http://simile.mit.edu/mail/ReadMsg?listName=Linking%20Open%20Data&msgId=20926 
>>>>
>>>>
>>>> And some refinements here:
>>>> http://simile.mit.edu/mail/ReadMsg?listName=Linking%20Open%20Data&msgId=20962 
>>>>
>> <snip>
>>> This discussion was indeed interesting :)
>>> I now tend to think that linking to a separate document is a cleaner
>>> way to go, but I am still concerned about auto-discovery. When you see
>>> something like:
>>>
>>> :New_York :morePersonsBornHere <http://example.org/persons_nyc.rdf> .
>>>
>>> in the representation of :New_York, you still need a way to describe
>>> the fact that :morePersonsBornHere links to a document holding lots of
>>> :birthPlace properties. Just saying that :morePersonsBornHere
>>> rdfs:subPropertyOf rdfs:seeAlso won't do the job properly - how can
>>> you tell before retrieving the whole document?
>>
>> Yves, the proposal above addresses this. There would be a triple:
>>
>>    :birthPlace link:subjectListProperty :morePersonsBornHere .
>>
>> This triple can be either directly in the :New_York description, or 
>> in the vocabulary (where you'd find it by dereferencing 
>> :morePersonsBornHere).
>>
>> The triple tells clients that they should follow the 
>> :morePersonsBornHere link if they are interested in :birthPlace 
>> triples. So, autodiscovery is solved.
>>
>
> Yes, it does work, but only for simple property lists. What about 
> "find here persons born in NYC between 1945 and 1975" ?
>
>
>
>>> But perhaps the approach I proposed when we discussed the void:example
>>> property could work, in exactly the same way as in [1].
>>>
>>> In the representation of :New_York, we could write something like 
>>> (in N3):
>>>
>>> <http://example.org/persons_nyc.rdf> void:example { :al_pacino
>>> :birthPlace :New_York }.
>>
>> N3 formulae cannot be expressed in RDFa or RDF/XML. How would you 
>> serialize this in practice?
>>
>
> As in the post I refered to: you can point to 
> http://example.org/dataset-example.rdf where you put these example 
> triples.
>
>
>>> Then, a SPARQL query like the following could find the documents that
>>> hold information about persons born in New York:
>>>
>>> SELECT ?doc
>>> WHERE {
>>> ?doc void:example ?g .
>>> GRAPH ?g {
>>> ?person :birthPlace :New_York .
>>> }
>>> }
>>>
>>> One of the good thing with this approach is that the "patterns" of
>>> information held in the target document can be arbitrarily complex -
>>
>> As far as I can remember, all the examples that people have given 
>> could be addressed with a simple property-based approach. Has anyone 
>> mentioned a use case that goes beyond looking for a single property? 
>> If not, then what does the additional complexity of this proposal buy 
>> us in practice?
>
> The example mentioned in my post uses more than one property, or the 
> exampl above.
>
>>
>>
>> “This is good because it can deal with arbitrary complexity” is a 
>> fallacy on the Web. Usually it translates as: “This is bad because it 
>> makes the common case harder.”
>>
>> (I note that the situation here is different from what you described 
>> in [1]. There it was about annotations on a dataset level. Here it is 
>> about annotating links that occur within many or all individual 
>> documents of a dataset.)
>>
>
> A RDF document is a dataset, and can be described as such :-)
>
Yves,

Just to clarify language (I do agree with your point). An RDF document 
is a resource (of type/kind "information resource") and as a result -- 
like all "Things" -- it can be formally described via its attributes and 
relationship properties :-)

Happy New Year!

Kingsley
> Cheers!
> y
>
>> Best,
>> Richard
>>
>>
>>
>>>
>>> and the only thing you have to do is to provide an example RDF graph,
>>> holding something representative of what you put in that document.
>>>
>>> Cheers!
>>> y
>>>
>>> [1] 
>>> http://blog.dbtune.org/post/2008/06/12/Describing-the-content-of-RDF-datasets 
>>>
>
>


-- 


Regards,

Kingsley Idehen	      Weblog: http://www.openlinksw.com/blog/~kidehen
President&  CEO
OpenLink Software     Web: http://www.openlinksw.com
Received on Sunday, 4 January 2009 17:47:09 UTC

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