- From: <noah_mendelsohn@us.ibm.com>
- Date: Fri, 29 May 2009 10:14:48 -0400
- To: Robin Berjon <robin@berjon.com>
- Cc: "Henry S. Thompson" <ht@inf.ed.ac.uk>, www-tag@w3.org
Thank you, Robin. I agree with many of your points. One clarification: Robin Berjon wrote: > Or more precisely, that a lot of languages are defined using > XML Schema — the distinction being that in a fair number of > cases that I've seen the schema may be in the specification > but then no one ever uses it as part of the production chain. Do you mean XSD is not used in production for validation or also that it's not used by tooling. If you mean in production for validation, then I think that's mostly true, except insofar as some databining tools do some sorts of input checking that are indirectly driven from schemas used to create the bindings. Also, it's my impression that XSD validation is often used for testing prior to production deployment, or perhaps for problem diagnosis. A certainly don't have quantitative information to back that up. If you mean that XSD isn't quite commonly used in production in conjunction with tooling that creates databindings, or that helps with the preperation of instance documents, I'm surprised. Not that such use is universal, but I would have thought it was common, and one of the reasons that many vertical standards do use XSD for their normative schames. Isn't this the typical way that schemas in WSDL are used, for example, e.g. with Visual Studio, its Eclipse-based Java competitors, etc.? Thank you. Noah -------------------------------------- Noah Mendelsohn IBM Corporation One Rogers Street Cambridge, MA 02142 1-617-693-4036 -------------------------------------- Robin Berjon <robin@berjon.com> Sent by: www-tag-request@w3.org 05/29/2009 09:46 AM To: "Henry S. Thompson" <ht@inf.ed.ac.uk> cc: www-tag@w3.org, (bcc: Noah Mendelsohn/Cambridge/IBM) Subject: Re: What would count as an unbiased survey? On May 29, 2009, at 14:41 , Henry S. Thompson wrote: > All of which raises the question: What _would_ constitute reliable > evidence of frequency of usage of the four major schema languages > (DTD, XSD, Relax NG, Schematron)? > > Note once again in closing that this is _not_ a "my language is better > than your language because more people are using it" discussion, but > rather an attempt to support the proposition that maintaining and > improving W3C XML Schema is important for W3C because it has a > substantial user community on (and off) the Web. If a survey is made, a good model could perhaps be the State of the Web 2008 survey: http://www.webdirections.org/the-state-of-the-web-2008/ That being said, sorry if I'm a little thick but I decreasingly understand what we would be trying to achieve with such a survey? As passionately as I may dislike XML Schema, there is little doubt that it is used a lot out there. Or more precisely, that a lot of languages are defined using XML Schema — the distinction being that in a fair number of cases that I've seen the schema may be in the specification but then no one ever uses it as part of the production chain. Which brings me to my primary point: more than reflecting on what schema language should get what resources in times of constraint, shouldn't we take a step back, look at how XML is used today, and figure out how we would like to help and shape it over the next decade? I'm willing to bet that any serious take on this will shake out precisely what needs be done around the schema issue — and will be more generally useful. In my experience, an awful lot of users out there pick XML Schema either because they don't know about the alternatives, or because "it's the W3C thing". Since as often as not they don't actually put the schema to use — in fact it's not rare that their schemata would be seriously broken, even though betters tools are reducing that issue — they don't really have an opinion on whether XML Schema or anything else is what they need. It's just there. This is strongly tied to the misperception that when defining a language one absolutely needs to have a schema, and the joint misperception that having defined a schema, processing rules for user- agent and versioning strategies are naturally solved issues. What I'm getting at here is that I believe that what we most need is some form of guidance — possibly in the form of best practices — for the usage of XML in various situations. Whether W3C is the best place to define these (given that they wouldn't produce a standard) is an exercise I'm happy to leave to another day — though an IG could perhaps work. There's a lot of experience in defining XML languages from various groups, notably inside W3C. It would be great at the very least to document that. It seems to me that whenever I stumble into a new standardisation effort both inside W3C and outside (e.g. OMTP, OMA, 3GPP, TV Anytime, MPEG...) I have to restate the very same things about picking the schema language that best fits based on genuine use cases and requirements rather than "just because", on the fact that a schema is rarely enough for validation, on versioning strategies, on user-agent error-handling, on processing models... and my throat feels rather raw from all that typing, especially since it usually takes a few rounds of discussion before people start to understand the problem. I'd love to have something to point at instead. I took a first semi-serious stab at it for the latest XML Prague (PDF: http://www.xmlprague.cz/2009/presentations/XMLPrague_2009_proceedings.pdf , slides + video: http://river-valley.tv/designing-xmlweb-languages-a-review-of-common-mistakes/ ) and it was well received — in fact I'm still getting questions about it even from people who weren't there. I have neither the time, the resources, nor the experience to elaborate on that in a solid, serious manner that will cover enough of the XML-using community — but I think that identifying problematic usage patterns will get us closer to something widely useful than figuring out which schema language is used most. The broader view on XML usage ought to shake out what really needs resources. -- Robin Berjon - http://berjon.com/ Feel like hiring me? Go to http://robineko.com/
Received on Friday, 29 May 2009 14:13:34 UTC