- From: <noah_mendelsohn@us.ibm.com>
- Date: Mon, 18 May 2009 21:27:11 -0400
- To: ashok.malhotra@oracle.com, Tim Berners-Lee <timbl@w3.org>
- Cc: "T.V Raman" <raman@google.com>, www-tag@w3.org, "David Ezell" <David_E3@VERIFONE.com>, cmsmcq@w3.org, holstege@mathling.com, "Michael Kay" <mike@saxonica.com>, sandygao@ca.ibm.com, ian@w3.org, shh@us.ibm.com
(I'm writing here as a TAG member, not as chair) Ashok Malhotra wrote: > I have some trepidation about this line of reasoning which would > seem to be: XML Schema is widely used, therefore it is good and > should continue! I have some trepidation about what's going on here, but for somewhat different reasons. After XSD 1.0 went to Recommendation, the XML Schema Working group was rechartered (more than once, FWIW). Here are some quotes from the latest charter [1], under which the Candidate Recommendation [2,3] has been published: "The XML Schema working group will maintain and revise the XML Schema specification developed beginning in 1998 and published as a W3C Recommendation on 2 May 2001. " [...] "Goals: to finish publication of version 1.1 of the XML Schema Recommendation, which corrects known errors and makes modest improvements to the language, and do preparatory work for a possible version 1.2. Changes in function or syntax incompatible with XML Schema 1.0 have been / will be made only if the resulting improvements compellingly justify the loss of interoperability with existing systems and documentation. Some substantive changes have been made in the interests of aligning version 1.1 with the needs of the XML Query 1.0, XPath 2.0, and XSLT 2.0 family of specifications and with XML 1.1. Requests for substantive changes may also come from other groups. [plus other goals not quoted]" Now, spurred by Rick Jelliffe's request [4], we're asking a question that boils down to: "shouldn't the W3C cancel this effort to provide incremental improvements to Schema 1.0, and instead start on a new, cleaner language?" I strongly believe that this is a question that should have been settled, and indeed was settled, when the working group was chartered with the above goals. The charter very clearly says: build on the XSD 1.0 base, and to the extent possible, retain syntactic compatibility. (There is a later goal that allows for experimentation with new syntax too, but that's in addition to not instead of enhancing the existing syntax; nowhere is a brand new language core discussed.) The W3C membership has every opportunity to provide guidance on the content of such charters, and the time to consider proposals for a new language would have been when the charters were written. To change the goals of an effort like this now is not only counter to the letter of the W3C process, it's hugely disruptive both in this particular case and as a precedent. There's no way that people like me are going to devote years to working in the W3C, toward agreed goals, if at the end we say: never mind, those weren't the goals. Rick raises some interesting and important technical points about XSD. No doubt it has shortcomings, though I don't necessarily agree with all that he lists. I also think XSD has some strengths, which he tends to de-emphasias, and FWIW the other languages have their own shortcomings, but my point here is not to claim that XSD is better, or that if I were starting from scratch I might not look very hard at just the technical direction that Rick proposes. The fact is that most of these concerns have been understood in general for a long time and Rick among others has raised them for a long time. Most of them were understood when the decision was made to create a charter that would focus on improving the experience of the many users who have adopted the W3C XML Schema Recommendation. We, the W3C, decided to invest in maintaining and enhancing a Recommendation that was being widely adopted. Indeed, evidence is clear that there is very widespread use of XSD, arguably extraordinarily widespread use of XSD, and so lack of adoption is in no way a reason to revisit the charter goals now. That is, IMO, the only reason we are in this thread considering relative rates of adoption of these languages at all. The fact is that XSD 1.0 is very widely used, and XSD 1.1 is designed to make the language more valuable for the many users who have invested in it. XSD 1.0 is also a W3C Recommendation, and while I have no problem with the W3C considering alternative languages on the merits from time to time, the presumption should be that we support and maintain our Recommendations, and that we honor our agreed charters. Noah P.S. The question of which schema languages are how widely used remains an interesting one, and if I turn up any useful facts based on my inquiries in IBM [5] I will pass them on. So far, all the evidence I've seen suggests that XSD is more widely used than the other languages by many measures, and by quite a significant margin, though there are interesting communities that strongly prefer RelaxNG and/or Schematron. There appear to be more .xsd documents accessible on the Web; I believe XSD is used by more widely-deployed tooling; and preliminary investigations suggest that XSD is used normatively by more "vertical" XML standards (some using XSD alone, and some using XSD+Schematron) than the alternatives. Of course, XSD also forms the type system for W3C XML Query, XSLT 2.0, and XPath 2.0. As I say, I'm still trying to check the facts on those adoption claims, and I'll pass on what I can. [1] http://www.w3.org/2006/06/XML/schema-wg.html [2] http://www.w3.org/TR/2009/CR-xmlschema11-1-20090430/ [3] http://www.w3.org/TR/2009/CR-xmlschema11-2-20090430/ [4] http://lists.w3.org/Archives/Public/www-tag/2009May/0021.html [5] http://lists.w3.org/Archives/Public/www-tag/2009May/0046.html -------------------------------------- Noah Mendelsohn IBM Corporation One Rogers Street Cambridge, MA 02142 1-617-693-4036 -------------------------------------- ashok malhotra <ashok.malhotra@oracle.com> Sent by: www-tag-request@w3.org 05/18/2009 07:05 PM Please respond to ashok.malhotra To: "T.V Raman" <raman@google.com> cc: www-tag@w3.org, (bcc: Noah Mendelsohn/Cambridge/IBM) Subject: Re: XML Schema usage statistics (WAS: Draft minutes of 2009-05-12 TAG weekly) I have some trepidation about this line of reasoning which would seem to be: XML Schema is widely used, therefore it is good and should continue! I think we need to ask some more nuanced questions. For example 1. Clearly all the statistics are based on Schema 1.0. Are the additions in 1.1 beneficial, necessary or excess baggage? Should the Schema WG be rechartered to add yet more features. 2. Is there a core subset of features in XML Schema that is heavily used and can be isolated? If so, should we consider a profile? I'm sure you smart folks can think of other good questions! All the best, Ashok T.V Raman wrote: > It would also be enlightening to find out how many of those XSD > files were generated from rng/ files. I know for a fact that many > groups inside W3C routinely produce their obligatory xsd schema > for their specs by first creating rng files. > > Julian Reschke writes: > > Paul Cotton wrote: > > > From the draft May 12 TAG minutes: > > > > > >> raman: XML Schema hasn't worked out very well. I'm skeptical that it > > > really dominates > > > ... > > >> timbl: Skeptical about preponderance of XSD usage, would like to see some > > > figures > > >> noah: Any volunteers? > > >> (silence) > > > > > > Searching Google code for .xsd files ( http://www.google.ca/codesearch?hl=en&lr=&q=file%3A.*%5C.xsd%24) finds 44,800 files. > > > > > > Searching Google code for .rng files ( http://www.google.ca/codesearch?hl=en&lr=&q=file%3A.*%5C.rng%24) finds only 3,000 files. > > > > > > Not necessarily a reliable survey but it certainly indicates that in publicly visible code stores indexed by "Google code" .xsd file occurrence is significantly greater than that of Relax NG files. > > > > > > Personal opinion: I expect that the ratio in enterprise systems whose code stores are not visible to a tool like "Google code" that this ratio would be even more slanted towards XML Schema. > > > > > > /paulc > > > ... > > > > Plus ~1000 in RNC (Compact) format. > > > > It would be interesting to have a comparison of the # of specifications > > that use XSD, RNC, or RNG as part of the spec text. > > > > BR, Julian > >
Received on Tuesday, 19 May 2009 01:25:57 UTC