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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: DTDs, W3C Schemas, RELAX NG, Schematron?
 Fundamentally I agree. But this comes down to what do we mean by "system" and "system scope". If we want seamless interoperability of a given system with another given system, value type standards are very sucessful. But the ubiquity of such? I seldom encounter such if ever. In our local systems, we have to support three database backends. For these, we map the value space datatypes in code and in the data dictionary (where the DD is really a document). ODBC layers take care of some of this and careful decoupling in the client does some of this. We choose what we will support based on issues other than standards or authority. Typically, price and performance are the first razors. Oracle is a wonderful performer but SQL Server is an adequate performer at a much better price break. So if a value space standard conflicted with that, we would ignore it. We would have to. It is the hard reality of competitive procurement that having the best system at the highest bid is *usually* a loser. So it comes down to the scope of the interoperating system vs the freedom of choice in implementation of any local system that must interoperate with all of the other "local systems". This is the dilemma that finally forced the W3C to buy into SGML On The Web. It loosened the definition of system and strengthened the power of "locale". It is why I say "there ain't no web; just parts and assemblies". Usually when someone disputes that assertion, the arguments come down to locus of authority to define scope for a system, and typically, they mean "all of the sharable information space as declared in URIs and governed by the W3C". It ain't happening. That definition is screwed for all practical purposes by the requirements on the local implementor. They might want to ramp back to something more workable and less ambitious. Pluggable types with a non-normative primitive set seems to be what is best and moreorless how we do business in other application domains. As John said, the TAO of RNG. Regardless of authority, that gives it an ecosystem survival edge. len From: W. E. Perry [mailto:wperry@f...] IMH (and oft-stated) opinion, we lose the very promise of XML. The number of correspondents and counterparties with whom we might exchange documents and perhaps execute transactions is vastly greater if the only required preconditions are lexical--i.e., the syntax of well formed XML. Granted, because we lack prior agreements in 'value space' on which to understand those interchanges and predicate those transactions, it will be necessary (and often long and painful) for us to build up with lexical tools the minimal one-to-one understandings we need to give each of those interactions its necessary meaning. The point is that it can be done, however distasteful the process for doing it anew with each new correspondent might seem to those who would rather short-circuit the effort by limiting their interactions to those who will accept a priori their definitions of 'value space'. I have spent more than twenty years working with applications built on RDBMs and relational wannabes. They are great and useful tools, but only in an homogenous enterprise network where the processing nodes have intimate (white box) knowledge of each others' processing and base their interoperability on working against identical data structures. Those are precisely not the conditions of the internetwork topology. If we want to extend the possibility of interoperability to every potential internetwork participant, we cannot begin by first constraining to universe of those to whom we will talk to only those who are willing to accept a priori our own peculiar and limited renditions of value space. 
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