W3C home > Mailing lists > Public > semantic-web@w3.org > July 2007

Re: URIs and Named Graphs

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Fri, 06 Jul 2007 13:19:06 +0100
Message-ID: <468E333A.9060300@hpl.hp.com>
To: Hans Teijgeler <hans.teijgeler@quicknet.nl>
CC: SW-forum <semantic-web@w3.org>, "Paap, Onno" <onno.paap@gmail.com>


feels like a mistake ...

Without having properly understood, I will guess a little ...

It seems that an ID like:


is representing a concept that is linked to <URI> by a sequence of other 

Since you are using named graphs, and you want this ID to identify a 
named graph then you are required to have a URI here.

I think I would suggest simply generating one - maybe


and then explicitly model the sequence of other concepts, relating this 
new concept to URI in another named graph.

While different URI schemes do provide various hierarchical naming 
schemes (e.g. the / paths in many schemes or the : paths in URNs), it is 
often a mistake to put too much semantics onto the hierarchy. Typically 
these hierarchies are about hierarchies of authority, not of semantics.
It is generally better to be fairly explicit about semantic 
relationships, and to describe these with a system intended to describe 


Hans Teijgeler wrote:
> Hi,
> We ran into a problem for which I ask advice from this esteemed forum.
> First some background information: we use the SW technologies in 
> conjunction with a generic data model to create a distributed data base 
> for each engineering project, involving large numbers (in the 
> hundreds) of quad stores per project.
> To give an example of using a data model "underneath" OWL: normally you 
> may see things like an <owl:Class rdf:ID="Car"/>.
> For us that would be: <part2:ClassOfInanimatePhysicalObject 
> rdf:ID="Car"/> where ClassOfInanimatePhysicalObject is an entity type in 
> our data model and an owl:Class.
> If an application has data that must be shared, that data is mapped at 
> the source from its proprietary format to ISO 15926-7 format, and stored 
> in a quad store that we call a "Façade".
> Only "owned" data are stored, other data a fetched with SPARQL for other 
> Façades.
> Data can be "handed over" to another Façade, thus also handing over 
> custody for that data.
> Quad stores that participate in a given project are known to a "CPF" 
> server (Confederation of Participating Façades), where we distrubute 
> SPARQL queries, consolidate query results, whilst controling access rights.
> For the Façades we use RAP, and want to use the 4th column of 
> their Named Graphs for dividing the quad store into partitions 
> like 'active data', 'archive', and the like. Actually we have nine such 
> partitions, but I won't annoy you with the details.
> We use URI#fragID's all over the place.
> The question is how we can dereference any such fragment identifiers 
> inside a particular partition without having to have nine endpoints 
> (which is costly and harder to manage).
> It would be nice if we could use composite fragment identifiers like 
> URI#partition#fragID, but the second hash # would not be allowed. If we 
> would use something like URI#partition__fragID that would be 
> well-formed, but hardly usable with generic browsers (I guess).
> Please shed some light on this.
> Regards,
> Hans
> ____________________
> OntoConsult
> Hans Teijgeler
> ISO 15926 specialist
> Netherlands
> +31-72-509 2005
> www.InfowebML.ws <blocked::http://www.infowebml.ws/>
> hans.teijgeler@quicknet.nl <blocked::mailto:hans.teijgeler@quicknet.nl>
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Received on Friday, 6 July 2007 12:19:39 UTC

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