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Re: DESCRIBE - description of a resource

From: Dan Connolly <connolly@w3.org>
Date: Mon, 22 Nov 2004 18:04:46 -0600
To: Alberto Reggiori <alberto@asemantics.com>
Cc: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Message-Id: <1101168286.27188.180.camel@dirk>
On Tue, 2004-11-23 at 00:35 +0100, Alberto Reggiori wrote:
> 
> here is a work in progress proposal to update the DESCRIBE section 10.3  
> of SPARQL document (partly reworking some text and examples provided by  
> Andy et al.)
> 
> 	http://www.w3.org/2001/sw/DataAccess/rq23/
> 
> $Revision: 1.139 $ of $Date: 2004/11/22 16:52:02 $
> 
> Comments and inputs welcome - I will keep on brainstorming and drafting  
> more...

It's good to have a complete proposal.

The material about DDDS and LSIDs doesn't seem to introduce
any new aspects of the design. It might fit better in our
Use Cases document.

If I understand correctly, what you're proposing is, formally,
just:

	DESCRIBE returns any RDF graph.

I encourage you to be more concise; i.e. to use the fewest
words that will make the design clear. I'm also interested
to see test cases.



The discussion of CBD and "bNode closure" suggests to me, again,
that DESCRIBE should be a separate query language, and that so
should CBD and the others. They should be given URI names
for use in the protocol. There should be tests with black-and-white
expected results, just like SPARQL SELECT. These languages
can share syntax etc. with SPARQL, but they should be distinguished
at the protocol level.

The way we've done this -- or started to do this, anyway -- 
in our SWAP toolkit is to have
properties that relate datastores, properties, and
classes to services:

In http://www.w3.org/DesignIssues/RDB-RDF.html we have
  
db:formService
  relates a database to a service that groks a syntax
  made from a particular HTML form I made up
db:sqlService
  relates a database to a service that takes SQL queries
db:deltaService
  relates a database to a service that accepts POSTed patches

and in http://www.w3.org/2000/10/swap/doc/Reach we have

log:definitiveDocument
  relates a property to a document from which you can GET
  a graph containing all true statements using that property
log:definitiveService
  relates a property to a service that takes queries (in N3,
  I think) and returns definitive (i.e. complete by definition)
  answers.


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E

Received on Tuesday, 23 November 2004 00:03:59 GMT

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