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Re: SemWeb Non-Starter -- Distributed URI Discovery

From: Charles McCathieNevile <charles@sidar.org>
Date: Mon, 21 Mar 2005 15:40:38 +1100
To: "Stephen Rhoads" <rhoadsnyc@mac.com>, semantic-web@w3.org, www-rdf-interest@w3.org
Message-ID: <op.sny0l0sxw5l938@researchsft>

On Sat, 19 Mar 2005 09:49:39 +1100, Stephen Rhoads <rhoadsnyc@mac.com>  
wrote:

> Until today, I considered myself to be squarely in the "slash" camp in  
> the hash/slash debate.  Then something occurred to me which has got me  
> all upset because it has serious implications for my project [1] --  
> which is inherently distributed in nature.
>
> As far as I can tell, there is no formal, generalized mechanism to  
> reliably query the owner of a URI in order to obtain an RDF Description  
> of that URI.

This problem is the one that URIQA solves admirably.

> And this is a serious impediment to the Semantic Web.

I don't think so. The point of the Semantic Web makes this one of the  
relatively little problems. RDF goes beyond "generic" XML in many ways,  
and one of the most important is the idea that many people independently  
contribute to a collection of information, without ever coordinating their  
work - that coordination is left to the use of the information.

So you not only want to query what the owner of a URI says about it, but  
also what others have said about it (IMHO a more important query in  
general). And then you want to be able to find contradictions and use them  
to decide which sets of statements are more reliable in some other case,  
or apply what you have learned elsewhere to resolving conlicts in  
statements you have gathered.

Finally, you need to have interfaces that make this sort of thing  
reasonable. I haven't seen any yet. I think the eventual contribution of  
interface and usability experts to the semantic web will be an interesting  
thing to watch, and an important step in the wide acceptance of the  
semantic web.

> "hashing" at least gets you part of the way because -- given an HTTP URI  
> containing a hash and frag ID -- it is *likely* that one can dereference  
> the URI into a document containing (amongst other things) an RDF  
> description of the URI in question.

I don't see how this is any more likely than where you have a slash-based  
namespace. (I am in the camp that thinks the hash/slash discussion isn't  
worth the effort).

> I read up a bit on SPARQL -- particularly the "SPARQL Protocol for RDF"  
> -- and, unless I'm misunderstanding, it seems to be the intended long  
> term solution to the problem described herein.  Is that correct?  Is it  
> expected that URI owner/minters will operate some sort of SPARQL server  
> for providing RDF Descriptions of their URIs?  Will there be some  
> convention as to the location of these servers such that one can  
> *reliably* and automatically query for an RDF Description of a URI?

I don't think this is how it will turn out. (I am just explaining my  
vision which is different from yours, so feel free to point out anything I  
say that is not very clever :-)

The value of SPARQL is that when you want to query an RDF store or  
service, you can write one query and send it to any number of different  
systems, and expect them to understand it.
This just makes the semantic web more interoperable than at present, where  
there are any number of query syntaxes and models in use at the  
machine/machine interface.

cheers

Chaals

-- 
Charles McCathieNevile                      Fundacion Sidar
charles@sidar.org   +61 409 134 136    http://www.sidar.org
Received on Monday, 21 March 2005 04:41:45 GMT

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