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Re: on log:definitiveService

From: Dan Connolly <connolly@w3.org>
Date: Fri, 18 Feb 2005 14:40:18 -0600
To: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Message-Id: <1108759218.4991.890.camel@localhost>

On Mon, 2005-02-14 at 08:52 -0600, Dan Connolly wrote:
> re ACTION: DanC to Write up definitive service concept
> 
> Darn... I thought it was written up in
>   http://www.w3.org/2000/10/swap/doc/Reach
> but on review, I see it isn't.

OK, somebody reminded me of the tests EricP and
I worked on a while ago...
  http://www.w3.org/2000/10/swap/test/dbork/

but we don't have a write-up, so here goes...

In OrderTracking1.n3 , we see...

<mysql://rdftest@swada.w3.org/OrderTracking/>
  is log:definitiveService of
    Orders:id, Orders:customer, Orders:product,
    Orders:orderDate ...

The idea is that if you've got a query ala

 SELECT ?productName, ?first, ?last
 WHERE 
 (?o Orders:customer ?c)
 (?o Orders:product ?p)
 (?o Orders:orderDate ?d)

 (?p Products:name :productName)

 (?c Customers:familyName ?first)
 (?c Customers:givenName ?last)

Then, since each of the properties in the query
is connected to <mysql://rdftest@swada.w3.org/OrderTracking/>
by log:definitiveService , you can delegate the query there;
i.e. if there are any answers to be found, that service has
them. It's definitive.

I expect lots of SPARQL services are interfaces to SQL
databases, where the data in that SQL database is definitive.
It's the customer database or whatever. All of widgetCo's
customers are in there; they have the power to close that
part of the world. Or it's a database of my CDs. I'm
the authority on which CDs are in my collection, so I
can reasonably publish a description of, say, my desktop
SPARQL query service using log:definitiveService .


Other examples in that /dbork/ directory demonstrate federated
query, where cwm will look at a query, realize that it
can be split into parts that can be handled by remote services,
delegate to them, and collect the results. I think our
implementation used the mysql protocol as a network protocol.
That's obviously to be replaced by the SPARQL protocol.

So that's the idea, on the front side of one page. Does
it merit more investigation?

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Friday, 18 February 2005 20:40:20 GMT

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