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Re: I guess it's a stupid questions.

From: Stefano Mazzocchi <stefano@apache.org>
Date: Tue, 16 Nov 2004 00:39:14 -0800
Message-ID: <4199BCB2.8050705@apache.org>
To: Eric Jain <Eric.Jain@isb-sib.ch>
CC: Danny Ayers <danny.ayers@gmail.com>, www-rdf-interest@w3.org

Eric Jain wrote:
> 
> Danny Ayers wrote:
> 
>> I've often had doubts, but haven't yet really encountered any
>> situation for which the lack of RDF contexts/quads has been a killer.
> 
> 
> Here is my use case:
> 
> We have a lot of documents each of which consists of several hundred 
> statements. Every document has some metadata such as when it was last 
> revised. This information can easily be indicated when such a document 
> is stored in a single file, using rdf:about="". The other solution of 
> course would be to reify all statements, which is definitely not 
> practical (which is not to say that reification isn't useful for making 
> assertions about individual statements).
> 
> The important point is that I can no longer make use of this metadata 
> after loading the data into an RDF database (e.g. retrieve a set of 
> statements or search only statements that are available under a license 
> that allows non-commercial use), unless the database supports some kind 
> of context.
> 
> I would be quite surprised if I were the only person on this planet with 
> this problem...

Oh, you are not.

And I have to add, context is important not only in terms of location 
(space) but also version (time).

But the more I think about it, the more I think that quads are in fact 
reifications and that I think that the fact that they are not practical 
might be a matter of implementation, not of a spec.

for example, you can totally imagine a triple store that allows you to 
reify a SparQL query, or if we can find a way to reify an entire 
document (means, the entire collection of triples).

I think it would be a mistake to specify what context is by harcoding 
one more metadata field to every statement. What next? what about 
licensing restrictions on the time about the change of the context of 
the statement?

the queries will get hairy, agreed, but context is something you know 
when you query, what you know where you enter data is just metadata 
about statements, and that's exactly what reification is all about.

-- 
Stefano.
Received on Tuesday, 16 November 2004 08:39:19 UTC

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