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

From: Richard Cyganiak <richard@cyganiak.de>
Date: Sun, 4 Jan 2009 19:00:56 +0000
Cc: Aldo Bucchi <aldo.bucchi@gmail.com>, "public-lod@w3.org" <public-lod@w3.org>
Message-Id: <599A6940-FE07-43FA-A835-B8B9DFD77236@cyganiak.de>
To: Yves Raimond <yves.raimond@gmail.com>

Yves,

Remember that Aldo was looking for something that allows clients to  
make smart decisions about when to follow a link out of an RDF  
document. He was not looking for something to describe the contents of  
RDF datasets on a high level.

More comments inline.

On 4 Jan 2009, at 14:28, Yves Raimond wrote:
>> 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" ?

I don't understand how you would express this using your proposal.  
 From what I've seen, you propose to provide a characteristic example  
subgraph of the linked document. How can you express range constraints  
using a subgraph?

>>> 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, to decide if I want to follow any of those links, I need to do  
an extra HTTP request to retrieve a single-triple document. I think we  
can do better than that. I also don't like the idea of having to  
potentially provide an extra example document *per link*.

>> 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.

The example in your post was about describing datasets. I don't see  
how it makes sense in the context of splitting up the RDF description  
of an individual resource.

>> (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 :-)

This isn't about what *can* be done, it's about what's *useful* to do.

I think that you have an interesting approach to describing RDF  
datasets, but I don't think that it is a good solution to the problem  
of hinting at the content that is available behind an RDF link.

Best,
Richard



>>> [1] http://blog.dbtune.org/post/2008/06/12/Describing-the-content-of-RDF-datasets
Received on Sunday, 4 January 2009 19:01:39 UTC

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