- From: Bradley P. Allen <ballen@siderean.com>
- Date: Tue, 17 Jun 2003 11:01:59 -0700
- To: "'Jim Hendler'" <hendler@cs.umd.edu>, <danny666@virgilio.it>, <www-rdf-logic@w3.org>
- Message-ID: <002101c334fa$8d30f490$6401a8c0@FISHBOWL>
Jim- I have two problems. The first is the effort to absorb yet another Semantic Web dialect in my application, and the second is the effort to explain the reasons for yet another dialect to a user community. The first is a short-term cost I have to bear. I fear the second can hinder adoption of the technology. As to the first: you're right. We shouldn't care, as we do routinely apply stylesheets to transform arbitrary XML into RDF/XML. It is a good thing that the Note contains a draft stylesheet in an appendix. But it's an interoperability issue because it's one more mapping that I will now have to worry about. However minimal that might be in this case, the working assumption was that all OWL in XML that we would encounter would be RDF/XML with OWL vocabulary. I am now disabused of that notion, and having complained, I will deal with it. With respect to the second: I assume, based on what you say, that some in the Webont WG feel that making it easier to write OWL DL correctly is worth abandoning RDF/XML as an authoring language. While I can appreciate their reasons, I think you are discounting the amount of FUD this creates among developers who are just beginning to understand what can be accomplished by authoring RDF/XML as it is today. I think it's worth addressing more explicitly in the Note and elsewhere, as you have in your email. - regards, BPA Bradley P. Allen President Siderean Software LLC 5155 West Rosecrans Avenue, Suite 1078 Los Angeles, CA 90250 USA phone +1 310 491-3424 fax +1 310 379-0231 web www.siderean.com -----Original Message----- From: Jim Hendler [mailto:hendler@cs.umd.edu] Sent: Tuesday, June 17, 2003 7:43 AM To: ballen@siderean.com; danny666@virgilio.it; www-rdf-logic@w3.org Subject: RE: Presentation Syntax - why? At 7:24 AM -0700 6/17/03, Bradley P. Allen wrote: Jim- Danny's main point, and I would agree with him, is that creating yet another syntax doesn't help those of us who are trying to build tools and field applications on top of either RDF or OWL. Seeing the Presentation Syntax document made my heart sink, because now I have yet another interoperability issue to address. The more interoperability burdens we have to clear, the slower we will be able to build applications to further adoption. There's a big difference between supporting yourself with tools to move from N3 to RDF, and having to support a user community that already has too many ways to express themselves in RDF. Throwing a stylesheet over the wall just doesn't cut it. I would agree with you that the process has been a visible one, but frankly, I feel a bit blindsided myself. - regards, BPA Bradley P. Allen President Siderean Software LLC 5155 West Rosecrans Avenue, Suite 1078 Los Angeles, CA 90250 USA phone +1 310 491-3424 fax +1 310 379-0231 web www.siderean.com Brad - this is what I don't understand. Why is the presentation syntax "another interoperability issue to address"?? Anyone using it will have to run the stylesheet and turn it into rdf/xml if they want any tools to do anything useful with it -- the reasoners, etc. will all use the RDF. So any tools you build will simply be enhanced by having more ontologies around in RDF/XML (or someone will build a crawler to find the XML ones and map to RDF or etc.) -- the implementor of an OWL or RDF tool shouldn't be effected by this at all. The reason some in the Webont WG like this, is because any document that validates against this XML schema will map to a legal OWL DL graph -- those are hard to check, and thus this will increase the number of people creating legal OWL DL ontologies. Those of us working in RDF will use OWL Full in most cases, which means we don't need to worry about the well-formedness conditions of the DL profile, but all OWL DL graphs are OWL Full graphs, so we'll be able to use our tools on them as well - win, win. so frankly, I see anything that causes more RDF to exist to be beneficial, and don't understand why "throwing a stylesheet over the wall just doesn't cut it", this is the WEB damn it, we win if more documents in more formats become interoperable -- not by saying everyone must do things in one particular way I know there are some good documents about "loose coupling" that have been chumped in the rdfig chat -- I'm a firm devotee of the loose coupling philosophy (and designed the entire DARPA DAML initiative to promote it) - and thus I don't see where the problem comes in -- what do you care what tool I use to create my graphs as longs as you can process them?? -JH -----Original Message----- From: www-rdf-logic-request@w3.org [mailto:www-rdf-logic-request@w3.org] On Behalf Of Jim Hendler Sent: Tuesday, June 17, 2003 6:00 AM To: danny666@virgilio.it; www-rdf-logic@w3.org Subject: Re: Presentation Syntax - why? [Please note, this message is in reply to one from Danny Ayers that was posted to public-webont-comments -- his message is included below -- I have moved it here to avoid confusion with Last Call comment replies on the public-comments list] At 11:47 AM +0200 6/17/03, Danny Ayers wrote: >At times it seems that the real activity of the WG can only be seen like the >structure of DNA was through X-Rays. A strange crystal that has just >appeared on a plate is the OWL Web Ontology Language XML Presentation Syntax >Note [1]. There doesn't appear to be any documentation of the role of >languages like this, and it's hard to place it in context. > >Reading the documentation for OWL it is clear that the intention was for it >to be a layer directly on top of RDF and RDFS, yet what the AS&S describes >needs a significant translation from OWL->RDF [2] and is currently only >mappable in the RDF->OWL direction through quite a convoluted procedure [3]. > >The impression this gives is that AS&S has in large part been constructed as >an entirely new language, with the RDF(S) considerations being retrofitted >late in the day. How much truth there is in this isn't really important, >what is important is that the roadmap has become smudged. > >I believe significant clarification is required around certain issues, in >particular those that lead to the Presentation Syntax. It appears that this >is a concrete representation of the AS&S, but for what purpose? If the >underlying model used by the AS&S is compatible with the RDF graph/triples >model, then why not use RDF/XML? Or is there such an air gap between the RDF >and OWL layers, that the OWL can fly free with it's own model, syntax and >serialization? > >On a practical level, the question is simple if a developer wishes to build >a Semantic Web application, where do they start? If they start with RDF now, >will they need a rework to be able to include OWL features without the >struggle of [3]? Or if they start with OWL AS&S will they lose the >compatibility with existing RDF data without building tools to carry out the >transformations of [2]? > >I realise this is relatively early days for OWL, it just seems from what's >being delivered that sometimes there are triples being asserted that are >dark for anyone outside of the WG. > >Cheers, >Danny. > >[1] http://www.w3.org/TR/2003/NOTE-owl-xmlsyntax-20030611/ > >[2] http://www.w3.org/TR/2003/WD-owl-semantics-20030331/mapping.html#4.1 > >[3] http://wonderweb.semanticweb.org/owl/parsing.shtml > >---- > >http://dannyayers.com Danny - since this document isn't a Last Call document (and isn't currently on the path to becoming one), I will take the liberty of interacting without a Working Group mandate. So these comments can be considered my own opinion, not those of the group. Frankly, I don't understand your point of view as raised in this message. Most of the work I do in RDF is done using N3, because I find it easier to use. My tools translate that N3 to RDF/XML, which is then used directly or turned into triples by some other tool. WOuld you argue against use of N3 or RDF/XML or Ntriples because they are all variants on using "pure" RDF triples (as are stored into the underlying RDF DB). OWL (Full) is a vocabulary extension to RDF (c.f [1] - my slides from the W3C track at WWW). It can be written directly in RDF/XML, it can be written in N3, and now, thanks to the document you are complaining about, there is an XML presentation that more directly corresponds to the abstract syntax we use in proving the semantic properties of OWL (and particularly the OWL DL profile of OWL). This presentation syntax comes with an XSLT that maps it into RDF/XML [2], and this is how we would expect it to interact with other OWL (and RDF Core and RDFS) tools. Thus,this syntax is just another way to produce OWL documents for people who have a different tool set. XML and RDF have different models, but many XML schemas can be mapped into perfectly reasonable RDF/XML, and this is one of them. It guarantees that documents that validate against this schema, and go through this XSLT, end up as legal RDF documents consistent with the OWL DL profile. This is why we stress its role as a presentation syntax - like N3 or Ntriples it is another way to look at RDF documents Other people are working on UML presentation syntax for OWL (the OMG has released a call to produce a two-way mapping between UML-2 and OWL), a graphical presentation syntax, a prolog front-end. All of these things lead to further adoption of OWL (and thus RDF) and I do not understand why you think they could be bad things. I also must state that I am personally upset at your charge that the activity of this working group is in any way mysterious. Guus and Ihave worked very hard as chairs, spurred on by Dan Connolly as team contact, to make sure that everything the WG did was in public, and that every decision we made was open to anyone who wanted to track it. The issue about whether to have an XML presentation has been in our publicly available issues list since Oct 2002 [4]. The WG decided to have this document as an "appendix" in Dec 02, but later decided a separate note made more sense. Further, our entire mail archive is open to the public, and if you search on "XML presentation syntax" you will find close to 150 messages dating back to May 2002 -- so you've had over a year to "study the chrystalline structure of our DNA -- we've made it damned easy to do! -Jim Hendler p.s. I might also suggest you read the article Bijan Parsia and I wrote in XML Journal [5], perhaps it can help clarify my position on why there is no contradiction to having an XML presentation syntax for an RDF vocabulary. [1] http://www.w3.org/2003/Talks/0522-webont-hendler/ [2] http://www.w3.org/TR/2003/NOTE-owl-xmlsyntax-20030611/owlxml2rdf.xsl [3] http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.17-XML-presentati on-syntax [4] http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.17-XML-presentati on-syntax [5] http://www.mindswap.org/papers/XML-J-Oct2002.pdf -- Professor James Hendler hendler@cs.umd.edu Director, Semantic Web and Agent Technologies 301-405-2696 Maryland Information and Network Dynamics Lab. 301-405-6707 (Fax) Univ of Maryland, College Park, MD 20742 *** 240-277-3388 (Cell) http://www.cs.umd.edu/users/hendler *** NOTE CHANGED CELL NUMBER *** -- Professor James Hendler hendler@cs.umd.edu Director, Semantic Web and Agent Technologies 301-405-2696 Maryland Information and Network Dynamics Lab. 301-405-6707 (Fax) Univ of Maryland, College Park, MD 20742 *** 240-277-3388 (Cell) http://www.cs.umd.edu/users/hendler *** NOTE CHANGED CELL NUMBER ***
Received on Tuesday, 17 June 2003 14:02:32 UTC