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Re: Rationale Behind The PSVI

• To: XML DEV <xml-dev@l...>
• Subject: Re: Rationale Behind The PSVI
• From: "W. E. Perry" <wperry@f...>
• Date: Thu, 16 May 2002 08:10:54 -0400
• Organization: Fiduciary Automation
• References: <8BD7226E07DDFF49AF5EF4030ACE0B7E06621C0C@r...> <3CE393FA.98731AC3@r...>

Ronald Bourret wrote:

> > Dare Obasanjo wrote:
>
> > The PSVI on the other hand doesn't strike me as useful in that manner.
> > Like the W3C XML Schema recommendation which spawned it, it conflates
> > many different issues into one entity including as type
> > information,validation information and default information.
>
> Agreed. The worst of it is that the PSVI information is just the
> information that appeared useful in the eyes of the authors of the schema
> spec. Different applications will care about different parts of it and I'm
> sure that reasonably clever people can come up with information that isn't
> included at all.

But that's just the point:  syntax doesn't have a data model; applications
do, inherent in the assumptions hard-coded in their processing. Schema
processing is an application or, as implemented in accord with W3C XML
Schema, several applications, including a sort of validation, a sort of type
decoration, and a sort of default value decoration. Each of these purposes,
implemented as the specialized application that it is, exhibits a processing
model which implies a most suitable data model for that process to operate
against. Until we can see those processing models--and the data models they
imply--as inherently belonging 'on top of' a syntax-processing parser, we
will continue to make the twin mistakes of forcing the particular data
demands of these applications down into the parser and misunderstanding the
stuff on which the parser operates as an 'infoset', delineated by those same
processing demands, rather than as the syntax of XML.

Respectfully,

Walter Perry

• References:
  • Rationale Behind The PSVI
    • From: "Dare Obasanjo" <dareo@m...>
  • Re: Rationale Behind The PSVI
    • From: Ronald Bourret <rpbourret@r...>

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