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Distributed querying on the semantic web

From: Phil Dawes <pdawes@users.sf.net>
Date: Mon, 19 Apr 2004 12:48:02 +0100
Message-ID: <16515.48242.246229.789670@gargle.gargle.HOWL>
To: www-rdf-interest@w3.org

Hi All,

I like Patrick Stickler's assertion that in order to participate in
the 'semantic web', http URIs should be dereferencable to some
information about the URI. I am considering how an infrastructure
could be built where this could be exploited for distributed queries.

The main problem with Patrick's concise-bounded-description idea from
this respect is how to find references to a term. 

For example:

(p:PhilDawes, foaf:knows, ?person) 

..is easy to resolve - just dereference p:PhilDawes and you probably
have the information you need. (I'm using dereference to mean 'look up
a description').

However

(?person, foaf:knows, p:PhilDawes)

.is much more tricky, since these assertions are likely to be made by
users external to the domain owner of p:PhilDawes.


Here's a straw-man solution:

- In addition to its bounded description, dereferencing p:PhilDawes
also provides all the references it knows about.

- When people author statements refering to p:PhilDawes, they POST
their triples to the description of p:PhilDawes. (Or maybe a third
party does).

- The representation of p:PhilDawes polls the reference URIs it knows
about periodically to keep its data up to date. (facilitating the
removal of triples as well as addition)


This would work, but the immediate problem for this solution is
scalability. In particular, domain owners of terms for common concepts
will require massive amounts of storage and bandwidth to maintain
their lists of references.


I was considering a couple of solutions:

- delegation of reference maintainers.
 
     The owner of the term delegates its references to a third party,
     more able to manage the storage and publication. The description
     it returns on dereference contains rdfs:seeAlso terms pointing to
     the reference maintainer.

- usage of owl to split the domains

     For example, terms like q:DoctorInMoseley could be used to
     aggregate a:Doctor and b:Moseley to split the load.  The a:Doctor
     description would then include a reference to the 
	  q:DoctorInMoseley rdfs:subClassOf a:Doctor term.
     and b:Moseley could contain
      q:DoctorInMoseley rdfs:subClassOf [a owl:Restriction; 
                                         owl:onProperty z:servesArea;
                                         owl:hasValue b:Moseley]. 
     statements.
     


I am keen to hear any ideas that others may have on the subject since
in addition to helping bootstrap the semantic web, this is a facility
that would be very beneficial in my work intranet environment.

Cheers,

Phil
Received on Monday, 19 April 2004 08:49:46 GMT

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