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Re: FW: URI string substructure queries - labelling/filtering use case

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Mon, 04 Oct 2004 15:19:38 +0100
Message-ID: <41615BFA.4040501@hp.com>
To: kendall@monkeyfist.com
Cc: RDF Data Access Working Group <public-rdf-dawg@w3.org>

At the moment, RDQL/Jena allows URIs to be tested as strings so regex matching 
just works.  Actually, anything [*] can be tested as a string - it just uses the 
lexical form of literals and URIs for graph nodes and properties.  Merely a 
pragmatic decision.  No prizes for finding where this causes problems (start 
with EQ and ==).

FWIW, plain literals can be tested as numbers (integers or doubles) by trying to 
parse them as such.  RDQL predates datatyping and I left it in as it is upwards 
compatible.

Now would be a good time to be a bit more principled.

	Andy

[*] inc. bNodes.

Kendall Clark wrote:
>>Possible use case story: 
>>[[
> 
> ...
> 
>>XYZ is attending an evening class on Description Logic and hopes to
>>eventually make use of the generalised description facilities in W3C's
>>OWL standard. In the meantime, millions of RDF triples have to be stored
>>and retrieved in an efficient manner, so XYZ looks to DAWG-compatible
>>RDF data storage systems. XYZ would be delighted to be able to have a
>>product-neutral, standard way of asking such a database questions like
>>"what documents have URIs that begin http://example.com/pics/adult/ ?",
>>"what documents have URIs that end ".png"?, "what documents have URIs
>>that contain the string "/adult/"?, so that such matching could be done
>>within the database rather than in application code.
>>]]
> 
> 
> Anyone care enough about this use case to see it included? I thought I
> did, but upon rereading it carefully, I'm not sure I like it at
> all. It breaks the webarch bit about URI opacity (well, I think, I'm
> never really sure what that *really* means...)
> 
> At any rate, were this my app, I'd probably store URIs as strings, in
> addition to storing them as URIs, in which case you could use DAWG's
> string handling bits to do what danbri's asking for. But danbri is
> bright and has surely thought about that?
> 
> Anyway, I owe the WG a draft v. soon now (like, in the next 2 hours or
> so), and I'm unsure what to do about this UC. If anyone has a thought,
> I'd like to hear it. :>
> 
> Thanks,
> Kendall
Received on Monday, 4 October 2004 14:19:53 GMT

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