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

Mon Jul 9 16:11:13 CDT 2007

I'm assuming that you'll be in Chicago then, to argue in favor of this...

Jery Cook wrote:
>
> 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
>
> ------------------------------------------------------------------------
>
> *From:* Jery Cook [mailto:twoencore at hotmail.com]
> *Sent:* Monday, July 09, 2007 11:10 AM
> *To:* 'jbrush at ronintech.org'; 'E-mail Rets-Dev'; 'rets-users at rets.org'
> *Subject:* RE: [Rets-dev] Comments on RQL, SQL, XPath and Joins, Why 
> not RDF/OWL?
>
> The RDF,RDFS,OWL specifications are final by the W3 in 2004, it is not 
> a question of maturity or complexity it is simply do you want do move 
> forward with it. The benefits of having RETs standard converted to an 
> Ontology, while having SPARQL endpoints, would be massive.., not to 
> mention so many other tools that can be used as clients to RDF(RETs 
> repositories)…I have been subscribed to this news letter for almost a 
> year…I see the same questions come up over and over, about how do I 
> query this, and that, ..why can’t I just query for images with a 
> criteria, why is it hard to find clients to Rets server, etc. using 
> RDF/OWL to describe your domain model,(Real estate information) will 
> effectively represent the structure/meaning of the information as well 
> as give developers/machine the an effective way to query and extract 
> that information.
>
> you all are doing a great job with the standard, it just looks from my 
> perspective it needs to be taking to the next level.
>
> I recommend the RETs community seriously considered having RDF/OWL on 
> there roadmap sooner, rather than later.
>
> References:
>
> http://xml.coverpages.org/ni2004-02-10-a.html
>
> http://www.semantra.com/pdf/literature/CIOs-guide-to-semantics.pdf
>
> Jeryl Cook
>
> ------------------------------------------------------------------------
>
> *From:* Jeff Brush [mailto:jeffbrush at hotmail.com]
> *Sent:* Thursday, May 10, 2007 6:24 PM
> *To:* Jery Cook; 'E-mail Rets-Dev'
> *Subject:* RE: [Rets-dev] Comments on RQL, SQL, XPath and Joins
>
>
> Jeryl,
>
> Technologies such as RDF, RDF Schema, OWL (Lite) and DAML+OIL were 
> reviewed by Bruce Toback and myself very early on in the RETS2 
> development process. They were found to be too complicated and not 
> ubiquitous enough for general use in the RETS standard at that time.
>
> When semantic web technologies become more mainstream I am sure these 
> types of technologies will be considered for inclusion by the community.
>
> Jeff Brush
> Ronin Technologies
>
> BTW-You're sig is spot on-IMHO.
>
> ------------------------------------------------------------------------
>
>
>
>
> > From: twoencore at hotmail.com
> > To: matt at pmptechnology.com; pstusiak at falcontechnologies.com; 
> rets-dev at rets.org
> > Subject: RE: [Rets-dev] Comments on RQL, SQL, XPath and Joins
> > Date: Thu, 10 May 2007 17:21:40 -0400
> > CC:
> >
> > Standards, standards :)
> >
> > Why not use RDF/OWL to describe RETS,
> > Use a tool like D2RQ that sits on a MLS database...expose the data via
> > SPARQL(SQL-like web query language).
> >
> > D2RQ
> > http://sites.wiwiss.fu-berlin.de/suhl/bizer/D2RQ/
> >
> > xml schemas , and RDF/OWL
> > http://www.pacificspirit.com/Authoring/Compatibility/OWLRDFExtensibility.htm
> > l
> >
> > SPARQL
> > http://en.wikipedia.org/wiki/SPARQL
> >
> >
> > someone could simply have a repository of SPARQL web-service endpoints to
> > RETS systems across the US...
> >
> > Jeryl Cook
> >
> > "I don't know the key to success, but the key to failure is to try to 
> please
> > everyone."
> > -Bill Cosby
> > -----Original Message-----
> > From: rets-dev-bounces at rets.org [mailto:rets-dev-bounces at rets.org] On 
> Behalf
> > Of Matt Lavallee
> > Sent: Thursday, May 10, 2007 12:35 PM
> > To: 'Paul Stusiak'; 'E-mail Rets-Dev'
> > Subject: RE: [Rets-dev] Comments on RQL, SQL, XPath and Joins
> >
> > Paul, et al.,
> >
> > Thanks for the background information on how RQL came to be chosen. 
> Paul's
> > point at the end does echo my sentiment in the earlier thread, 
> knowing full
> > well
> > that implementing XPath is a sea-change from providing a 
> pseudo-SQL-to-SQL
> > translator, with potentially limited return.
> >
> > However, with all due deference to the MLS Vendors, there is a 
> genuine need
> > for
> > some sort of "glue" operation to deal with the new distribution of 
> data. I
> > sincerely feel it's unreasonable to expect three (or more) queries to get
> > related information strictly because of an inadequate querying 
> interface --
> > particularly when we know that the data store itself supports such
> > operations.
> >
> > Now, whether that glue be a graceful evaluation of the hierarchical 
> data (as
> > in
> > my implicit-relation RQL example) or a classic RDBMS implementation 
> of JOINs
> > doesn't really matter to me... but I think one of the two needs to 
> exist to
> > consider the query feature functional.
> >
> > Also, if Media doesn't have a Resource type of its own, how can one query
> > for
> > Media without using a schema?
> >
> > -Matt
> >
> > > -----Original Message-----
> > > From: rets-dev-bounces at rets.org [mailto:rets-dev-bounces at rets.org] On
> > Behalf
> > > Of Paul Stusiak
> > > Sent: Tuesday, May 08, 2007 12:18 PM
> > > To: E-mail Rets-Dev
> > > Subject: [Rets-dev] Comments on RQL, SQL, XPath and Joins
> > >
> > > There have been some comments on the rets-dev list recently about
> > > querying in RETS2
> > >
> > > Some background may help people understand where we are.
> > >
> > > The original RETS2 documents included DMQL2 and XPath. Some feedback
> > > from surveys indicated that there was a significant group of 
> developers,
> > > those who did not come to the meetings were having conceptual problems
> > > with DMQL. Specifically, they were asking questions like "why isn't it
> > > SQL? we understand SQL..." With some more digging, some of the concerns
> > > boiled down to the use of symbols for logic operations. There had been
> > > an intent to replace DMQL2 with something like DMQL3 - fixing 
> several of
> > > the problems with the BNF of DMQL2 that caused difficulty when using
> > > parser-generators like antlr and others.
> > >
> > > There had been a group, I think Sergio and Steve and Stuart were 
> part of
> > > it, to evaluate the future direction for querying. I don't see the
> > > document on rets.org, so I've asked Sergio if he can find it and 
> post it
> > > to rets-dev and we'll put it up on the website.
> > >
> > > My recollection is that this group looked at DMQL, XPath and SQL and
> > > determined that DMQL was the way to go.
> > >
> > > Given these facts, the work on RETS2 focused on DMQL and had some XPath
> > > included because it is a natural for XML. An alternative was 
> proposed by
> > > Wantao Zhou of FirstAmerican. This was to XML-ify the DMQL. It was well
> > > thought out, but was not considered appropriate by the community.
> > >
> > > As the work on DMQL2+ was going on, it was pointed out that Dave 
> Dribbin
> > > and Keith Garner of CRT had already done some of this work in one of
> > > their products that were open source. Dave reworked some of the BNF to
> > > have only the feature set of DMQL2. This was a properly formed BNF that
> > > resolved some of the issues that made it more difficult to feed to
> > > parser-generators and added some syntactic candy by changing the '|',
> > > etc. with 'OR'. No change of intent, but the syntactic candy should 
> help
> > > those who were thrown off by the different operator representation.
> > >
> > > RQL appears to offer protection of the existing substantial investment
> > > in DMQL that server vendors have while providing response to some 
> of the
> > > impediments to adoption that the different operator representations 
> cause.
> > >
> > > As RETS2 went forward with the inclusion of XPath, there was a lot of
> > > resistance to using it from the existing vendors. To get agreement on
> > > RETS2, it was removed from the Service document. The Service document
> > > does permit additional query languages but mandates only RQL. It is
> > > possible that cutting XPath from RETS2 was incorrect.
> > >
> > > I would also point out that the RETS2 specification is a suite of
> > > documents. There may be additional documents that need to be added.
> > >
> > > While SQL is the language used on the repository for RETS1 - there were
> > > only two vendors who were using other storage techniques than a
> > > relational database that I know of, not all storage solutions use SQL.
> > > The specification has attempted to separate the specification from the
> > > implementation.
> > >
> > > --
> > > Paul Stusiak
> > > Falcon Technologies Corp.
> > >
> > > _______________________________________________
> > > Rets-dev mailing list
> > > Rets-dev at rets.org
> > > http://lists.rets.org/mailman/listinfo/rets-dev
> >
> >
> > _______________________________________________
> > Rets-dev mailing list
> > Rets-dev at rets.org
> > http://lists.rets.org/mailman/listinfo/rets-dev
> >
> > _______________________________________________
> > Rets-dev mailing list
> > Rets-dev at rets.org
> > http://lists.rets.org/mailman/listinfo/rets-dev
>
>
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-- 
Paul Stusiak
Falcon Technologies Corp.