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At 02:02 PM 4/23/2003 -0400, John Cowan wrote: >Dan Vint scripsit: > > > I swallowed hard on the idea of well-formed documents, but have learned > > to live with that, but now not even being able to have a standard way to > > determine if this XML file is supposed to be compliant with a DTD or > > schema is almost too much to accept. > >It's a different model. An SGML or XML DTD is *logically inside* the >document (even if it's physically outside through the use of entities; >XML puts some restrictions on DTDs when physically inside, but that >doesn't affect the point), and so validation answers the question "Is >this document self-consistent?" I understand the difference in the models for processing, but the fallout of the DTD process was that I identified as the creator of the document how I intended for it to be processed and potentially which version of that DTD that I wanted used. Theoretically, the DTD was always an out side file and it had a unique public identifier that I referenced for this purpose. I was looking for that similar identification. Len talks about the "contract" all the time, to me just having the data without a reference to what I intended it to conform to is not much of a contract. Also what happens with all this legacy stuff and loose files? Ok I have an XML stream, but what good is that too me if I don't know what I was supposed to manage it with? I get and build XML files all the time and NEED to have the reference to something just so I can remember what I was working with. It doesn't take more than a week of inactivity to forget what file Z was used for. I was sort of looking at the targetNamespace as providing some of the benefit of the public identifier if you followed the process of putting a version number in the URL and changed it with each significant change. I was also looking for something that would differentiate a well-formed document (maybe not even built to a DTD or Schema) from one that was built for a schema. In the case of a schema based document I was expecting a targetNames, schemaLocation or nanamespaceSchemaLocation to at least flag or trigger schema based processing. >A WXS or RNG or Schematron schema, like an architectural meta-DTD, is >*logically outside* the document, and validation against it answers the >question "Is this document consistent with this schema?" This entails, >of course, that there might be more than one schema with which the >document is consistent. That being so, there can be no exclusive means >of referring to *the* schema against which a document is to be validated. But how many people are working with more than one schema? Even if they are wouldn't it be good to come up with a method to relate all the schemas together and have a universal identifier assigned that is then tracked in the document? Sort of a hybrid use of a public identifier and a catalog to manage this stuff? Maybe the big difference is that SGML/XML was built for documents and they are intended to live more than the nano-second needed to send it across the wire and it is never stored or referenced in that form again. Where a document is not so transient and is stored in many places on my hard drive and different systems. And I will go back to some of those files over several years (or at least days) time. It would have been nice if some of this functionality was allowed. ..dan >-- >Some people open all the Windows; John Cowan >wise wives welcome the spring jcowan@r... >by moving the Unix. http://www.reutershealth.com > --ad for Unix Book Units (U.K.) http://www.ccil.org/~cowan > (see http://cm.bell-labs.com/cm/cs/who/dmr/unix3image.gif)
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