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RE: Semantic Web Phase 2 Activity - Protocol

From: Graham Moore <moore@ontopia.net>
Date: Tue, 11 Nov 2003 15:42:28 +0100
To: <www-rdf-interest@w3.org>
Message-Id: <E1AJZo9-0001rJ-00@sandbox.ontopia.net>


Given that the semantic web protocol issue has come up. I would just like to
mention that the 'RDF Net API' has been published as a W3C member submission
at

http://www.w3.org/Submission/2003/SUBM-rdf-netapi-20031002/

The W3C comment describes how this protocol relates to the work by Patrick
and others in this area.

Both Andy and I would really like to have some comments and discussion about
this submission as we really hope that it can spur on the creation and
adoption of a semantic web protocol.

Cheers,

Graham

----------------------------------------------------------------
Graham Moore, Ontopian            moore@ontopia.net
GSM: +47 926 82 437           http://www.ontopia.net


-----Original Message-----
From: www-rdf-interest-request@w3.org
[mailto:www-rdf-interest-request@w3.org] On Behalf Of Patrick Stickler
Sent: 11 November 2003 13:00
To: leo@gnowsis.com; www-rdf-interest@w3.org


On 2003-11-11 12:27, "ext Leo Sauermann" <leo@gnowsis.com> wrote:

> 
> In the last time I stumbled across the "Semantic Web Phase 2 Activity"
> more often and expect that some people involved read this.
> 
> In my writing code, I clearly miss some things that would make life
> easier:
> so I think that they should be included in Phase2.

We clearly share similar concerns/interests.

> TimBl wrote that you need three things to build a WWW:
> HTTP, HTML, URL
> We clearly miss the HTTP part so at first i ask for :
> 
> 
> A PROTOCOL
> ==========
> uriqa, Joseki, Sesame, they all have protocol.
> 
> We are missing a protocol, so do something about it.
> 
> important:
> - distributed approach, how to identify the server when querying about 
> a given resource.
> (see my comments about this in
> http://lists.w3.org/Archives/Public/www-rdf-interest/2003Oct/0155.html
> )
> 
> - queries over the protocol with query language

I'm not sure if full querying must be bound to the core protocol, as the
core protocol should be as ubuiquitous as possible and having too great an
implementational burden would hamper that.

I've drawn the line between a minimal protocol for "bootstrapping" the SW
(i.e. URIQA) via which one can discover other supported protocols, APIs,
services, etc. which a given server may support. E.g. if one executes the
request

MGET http://sw.nokia.com HTTP/1.1

one gets back a description of the Nokia Semantic Web Server which indicates
various services available, including a URIQA service for arbitrary URI
queries as well as an RDFQ service for advanced queries. I.e.

<?xml version="1.0"?>
<rdf:RDF 
   xmlns:swarch="http://sw.nokia.com/SWArch-1/"
   xmlns:uriqa="http://sw.nokia.com/URIQA-1/"
   xmlns:webarch="http://sw.nokia.com/WebArch-1/"
   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:owl="http://www.w3.org/2002/07/owl#">
    <rdf:Description rdf:about="http://sw.nokia.com">
        <rdf:type rdf:resource="http://sw.nokia.com/URIQA-1/Server"/>
        <uriqa:service rdf:resource="http://sw.nokia.com/uriqa"/>
        <swarch:service rdf:resource="http://sw.nokia.com/rdfq"/>
        <webarch:service rdf:resource="http://sw.nokia.com/id"/>
    </rdf:Description>
</rdf:RDF>

Standardization of other, more involved protocols/APIs for advanced query,
distributed knowledge management, rules, etc. need not overburden the
deployment of that essential bootstrapping functionality.

> and some kind of
> "Concise bounded description"

Most definitely.

> 
> 
> A Query Language
> ================
> RDQL, RQL ....
> 
> all nice but a common lanugage should include :
> - OUTER JOIN Queries, (optional matches)
> - giving a "template" for a subgraph to be retrieved, f.e.
> "give me triples that do: (?x rdf:type foaf:Person), (?x * *)"
> 
> (these two things are in some projects, but not in all etc....)

I think that RDFQ [1] includes both of the above, but would be very keen to
learn if it didn't.

The boolean logic of an RDFQ query input graph is

rdf:RDF
{
   rdfq:Query
   {
      ...
   }
OR
   rdfq:Query
   {
      ...
   }
OR
   rdfq:Query
   {
      rdfq:Target
      {
         ...
      }
   OR
      rdfq:Target
      {
         ...
      }
   OR
      rdfq:Target
      {
         PROPERTY VALUE
      AND
         PROPERTY VALUE
      AND
         PROPERTY rdfq:Value
         {
            CONSTRAINT=true
         AND
            CONSTRAINT=true
         AND
            ...
         }
      }
   }
}

Optional matches could also be defined in terms of a best-match algorithm,
where targets are ranked according to the degree to which the template
matches their description (by some formula).

I.e., RDFQ provides the means to specify one's ideal target, whether or not
matched resources satisfy that ideal and whether such less-than-ideal
resources are described in the results is not necessarily dependent on the
query language.

Though, if this is a strongly desired feature, it would be straightforward
to define a subclass of rdfq:Value, i.e. rdfq:OptionalValue, or some similar
machinery to provide for this.

> 
> URI Crisis guide
> ================
> Personally, I think that
> "http://www.amazon.com/exec/obidos/ASIN/0679600108/qid=1027958807/sr=2
> -3 /ref=sr_2_3/103-4363499-9407855" is a webpage that offers a book 
> for sale and that means
> 
> <http://www.amazon.com/exec/obidos/ASIN/0679600108/qid=1027958807/sr=2
> -3 /ref=sr_2_3/103-4363499-9407855> <sale:offers> 
> <http://www.isbn.org/US/0679600108>
> 
> and sadly, the www.isbn.org guys don't offer a search for books on 
> their site and so we can't extract a url for  0679600108 from their 
> site, but this ought to change !
> 
> I think that <http://www.isbn.org/US/0679600108> is a global 
> identifier for the book and it should be used to represent the concept 
> of the book and used extensively in databases of Bookstores and 
> semantic text rezensions all over the world.

I agree. Though such use could only ever be voluntary.

> But thats what I think and the W3C ought to state what we should do 
> now about it and create some document where this is settled.

I think the most that could/should be done is to provide the means for folks
to say what their URIs denote and provide consistent, standardized access to
descriptions of those resources. I don't think we can tell folks that they
must create certain URIs or what URI scheme they must use, etc. -- though
promotion of certain "best practices" is certainly something the W3C could
(and of course is working to) provide.

> I think this problem can be best settled by philosophers, librarians 
> and SemWeb people in concert.

Now *that* sounds like a fun party ;-)

Cheers,

Patrick

[1] http://sw.nokia.com/rdfq/RDFQ.html


> 
> 
> Greetings
> 
> Leo Sauermann
> www.gnowsis.com
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Dear God,
> For christmas 2003 I wish that you solve these things.
> :-)
> 
> 
Received on Tuesday, 11 November 2003 09:49:40 GMT

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