[Rets-dev] Comments on RQL, SQL, XPath and Joins, Why not RDF/OWL?

[Jeff Brush]

One of the design goals of the RETS2 SOAP transport was to be open about
the formats of the response data payload - so an RDF response is
permitted inside the RETS2 SearchResponse wrapper, as are XMLs, GIFs,
PDFs,  or even ZIPs and Excel spreadsheets, should the server choose to
implement these formats. 
 
A query type of SPARQL or XQuery is also possible should a server choose
to implement it as an additional query language. (This can be difficult,
but not impossible, as the predominant persistence model is table/field
based.)
 
To the best of my knowledge, there is not a strong business case for an
MLS requiring RDF/SPARQL today, but I believe the transport spec will
allow it should the need arise.
 
 
Jeff


  _____  

From: rets-dev-bounces at rets.org [mailto:rets-dev-bounces at rets.org] On
Behalf Of Jeryl Cook
Sent: Wednesday, July 11, 2007 11:25 AM
To: Matt Lavallee; jbrush at ronintech.org; 'E-mailRets-Dev'
Subject: RE: [Rets-dev] Comments on RQL, SQL, XPath and Joins, Why not
RDF/OWL?



>>excessively verbose syntax, it provides no direction to structuring
our data and is only arguably useful in meta-meta-data scenarios.
Consider this example:
<http://www.daml.org/cgi-bin/hyperdaml?http://www.daml.org/2001/10/html/
airport-ont#Airport>
http://www.daml.org/cgi-bin/hyperdaml?http://www.daml.org/2001/10/html/a
irport-ont#Airport>>
RDF/XML is not meant for "you"(human beings) to interpret it is for
machines..trying to figure out a "sense of hierarchy" will drive anyone
mad.  
in the link u have about the subject "Airport" , your not suppose to
print a document out like this and read through it...you missing the
point.

>>SPARQL is equally overburdened with complex syntax due to the
URI-based nomenclature of RDF>>
URIs are complicated?
this query which finds the minimum price of every propertyListing in the
underlying default graph:

  PREFIX ex: <http://rets.org/>
  SELECT ?propertyListing ?minprice
  WHERE {
    ?propertyListing a ex:propertyListing ; ex:price ?minprice .
    OPTIONAL { 
      ?propertyListing ex:price ?otherprice . 
      FILTER( ?otherprice < ?minprice ) .
    } .
    FILTER ( !bound(?otherprice) ) .
  }


not that complicated to me..

Look, didn't mean to start a flame war here :), i only stumbled on RETs
, trying to develop a site for my brother who is a relestate
agent/investor....& i just happen to be a software engineer for a
company that specializes in building "Knowledge Management" systems....
i saw a connection between semantic technology and what RETs does for
the relestate industry..and put my 2 cents out there..

as far as being mainstream, many companies are building on this semantic
technology in great numbers..Oracle, Microsoft  is using RDF/OWL, and
lets not forget RSS feeds(RDF..) ..there are a good number of software &
web clients that allows people to browse via web and visually RDF
documents(could easily be property listings)..

i think u all are doing a great job(i say it again), just throwing some
ideas out there for ya, I've been just an outside looking and reading
the messages.. ..i am in total agreement u shouldn't implement
everything that comers out of W3, after while building solutions based
on bleeding edge,you can easily get hurt!..but its worth another serious
look.  I wish i could make it to Chicago, but ill be in Aruba :).


Jeryl Cook



  _____  

From: matt at pmptechnology.com
To: twoencore at hotmail.com; jbrush at ronintech.org; rets-dev at rets.org
Subject: RE: [Rets-dev] Comments on RQL, SQL, XPath and Joins, Why not
RDF/OWL?
Date: Mon, 9 Jul 2007 16:36:51 -0500



While it's all well and good to consider emerging technology, it's
notable that RDF had been formally accepted in 2004 and has yet to see
any mainstream adoption. Beyond it's (in my opinion) excessively verbose
syntax, it provides no direction to structuring our data and is only
arguably useful in meta-meta-data scenarios.  Consider this example:

http://www.daml.org/cgi-bin/hyperdaml?http://www.daml.org/2001/10/html/a
irport-ont#Airport

 

.the ability to validate the document (not to mention infer any sense of
hierarchy) is fairly limited, and may not be applicable at all in an
infinitely-extensible model such as ours.

 

SPARQL is equally overburdened with complex syntax due to the URI-based
nomenclature of RDF.  If one compares the "suggested Extended RQL" to
SPARQL, I don't think there's much debate.  SPARQL requires you to
construct the element graph in the query and employs its own unique
filter language for criteria.  At least our [suggested] form follows SQL
for semantic construct, then XPath for element notation.

 

-Matt

 

From: rets-dev-bounces at rets.org [mailto:rets-dev-bounces at rets.org] On
Behalf Of Jery Cook
Sent: Monday, July 09, 2007 3:07 PM
To: 'Jery Cook'; jbrush at ronintech.org; 'E-mail Rets-Dev'
Subject: RE: [Rets-dev] Comments on RQL, SQL, XPath and Joins, Why not
RDF/OWL?

 


W3C Recommendations: Resource Description Framework (RDF) and Web
Ontology Language (OWL).

The World Wide Web Consortium has announced "final approval of two key
Semantic Web technologies, the revised Resource Description Framework
(RDF) and the Web Ontology Language (OWL). RDF and OWL are Semantic Web
standards that provide a framework for asset management, enterprise
integration and the sharing and reuse of data on the Web. These standard
formats for data sharing span application, enterprise, and community
boundaries, since different types of users can share the same
information even if they don't share the same software."

The Resource Description Framework (RDF) is a "language for representing
information about resources in the World Wide Web. It is particularly
intended for representing metadata about Web resources, such as the
title, author, and modification date of a Web page, copyright and
licensing information about a Web document, or the availability schedule
for some shared resource. However, by generalizing the concept of a 'Web
resource', RDF can also be used to represent information about things
that can be identified on the Web, even when they cannot be directly
retrieved on the Web. Examples include information about items available
from on-line shopping facilities (e.g., information about
specifications, prices, and availability), or the description of a Web
user's preferences for information delivery." The W3C RDF Recommendation
is presented six parts: Primer, Concepts, Syntax, Semantics, Vocabulary,
and Test Cases.

The OWL Web Ontology Language is "intended to be used when the
information contained in documents needs to be processed by
applications, as opposed to situations where the content only needs to
be presented to humans. OWL can be used to explicitly represent the
meaning of terms in vocabularies and the relationships between those
terms. This representation of terms and their interrelationships is
called an ontology. OWL has more facilities for expressing meaning and
semantics than XML, RDF, and RDF-S, and thus OWL goes beyond these
languages in its ability to represent machine interpretable content on
the Web. OWL is a revision of the DAML+OIL web ontology language
incorporating lessons learned from the design and application of
DAML+OIL." W3C has published the OWL Recommendation in six documents:
Use Cases, Overview, Guide, Language Reference, Test Cases, and Language
Semantics and Abstract Syntax.

Sounds like a perfect match for Rets to me.

 

Jeryl Cook

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