[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Personal reply to Edd Dumbill's XML Hack Article wrt W3C XML Schema
Richard Tobin wrote: > Are the simple types sufficiently uncontroversial to form a basis for a > common "typed infoset"? I would argue that their very specification violates the unique nature of XML. In my (apparently unorthodox) view the unique property of XML is that it places the instance before the type. Said differently, XML is intended to be eXtensible through Markup in the instance, not through the extension of a schema, DTD or other data model. The uniquely XML notion of well-formedness as the common baseline of conformance should guarantee this primacy of the instance. By this argument, simple types (and indeed any data schematics) are as derived from the instance document for the execution of particular processing on a given occasion. The 'validity' of the data is a determination that it satisfies the requirements of processing on that unique occasion. From that perspective, the 'typed infoset' elaborated from the instance data is not 'common', in the sense that that it can predictably be elaborated on other occasions from similar data instances. There is however an 'instance' typed infoset which might be elaborated from the specific processing of any XML document on a given occasion and which might usefully be the basis for further processing. A sequence of such instance infosets could be pipelined between processes which might be coupled in unique sequences in order to accomplish data (or document) processing specifically suited to the circumstances in which it is executed. Specifying data typing which depends in this way upon the instantiation of instance XML on a given occasion to meet the expectations of a given process is admittedly a radical departure from the philosophical premises on which the Schema WG (and other WG's whose work is alleged to be too dependent on the Schema WD) operate. It is nevertheless a method for achieving schema specification--and, I would argue, the only method--which does not violate the salient point of well-formedness as the unique baseline of XML conformance. Respectfully, Walter Perry
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