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RE: Joseki, an RDF server. v1.0

From: Seaborne, Andy <Andy_Seaborne@hplb.hpl.hp.com>
Date: Tue, 21 Jan 2003 11:42:34 -0000
Message-ID: <5E13A1874524D411A876006008CD059F038D40D2@0-mail-1.hpl.hp.com>
To: "'Eric Jain'" <Eric.Jain@isb-sib.ch>
Cc: rdf-interest <www-rdf-interest@w3.org>

Eric,

Let me see if I understand your question: you want to retrieve the RDF
subgraph rooted at <a> using <hasItem> as a property to indicate which arcs
to traverse.  Or did you mean something like "everything about <a>" in a
more general way defined by the nature of the application?  Or was the
subgraph of interest defined in some other way?

I'm afraid the answer for Joseki as it is today is "no" in general because
both do arbitrary traversal so RDQL can't express it in one single query.
You can approximate by asking several queries like:

SELECT * WHERE (<a>, <hasValue>, ?v)
SELECT * WHERE (<a>, <hasItem>, ?b) (?b <hasValue> ?v)
...
which isn't very satisfactory when what you really want is a model that
provides transitive <hasItem> relationships then the single query 
	SELECT * WHERE (<a>, <hasItem>, ?b) (?b <hasValue> ?v)
will get all depths of <hasItem> relationships.

You can add a query languages yourself - all query processors are plugins.
The website has an explaination of how to do this.

	Andy

> -----Original Message-----
> From: Eric Jain [mailto:Eric.Jain@isb-sib.ch] 
> Sent: 21 January 2003 11:33
> To: Seaborne, Andy
> Cc: rdf-interest
> Subject: Re: Joseki, an RDF server. v1.0
> 
> 
> > Query provides a common framework for handling models from small to 
> > large.
> 
> Is there any way to efficiently retrieve all statements 
> associated with a given resource?
> 
> Example: Query for <a> returns:
> 
> <a> <hasItem> <b>
> <b> <hasValue> 'x'
> <b> <hasItem> <c>
> <c> <hasValue> 'y'
> 
> 
> --
> Eric Jain
> 
Received on Tuesday, 21 January 2003 06:46:28 GMT

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