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Re: Validation API, was: Regarding the vote on XML Schema.
- From: Wayne Steele <email@example.com>
- To: Tony.Coates@reuters.com, firstname.lastname@example.org
- Date: Tue, 24 Apr 2001 12:36:49 -0700
I think this discussion has happened before.
IIRC, the consensus was that more is needed than a 'pluggable validator'
API; each schema technology brings its own infoset contributions.
'Validation' can be seen as a special case of an infoset contribution.
What's needed is a mechanism to plug-n-play infoset annotations into a
document processing stream.
I have this XMLDocument.
I want to validate a fragment of it against this DTD I've got (this also
fills in some default attributes I need).
I want to use an XML Schema to 'paint' data types onto the doc.
I run an XSLT2 transform on the document, keeping the datatype
information intact in the output document.
I want to overwrite _some_ of the datatype information in the new
document, with some specific rules I hacked up.
I want to validate the document using a set of Schematron rules.
I also want to do this without scribbling on the document instance, because
it's on a read-only medium and it's huge.
Maybe that is too hard.
I think people are still trying to narrow down what these 'infoset
contributions' are, and what they look like. Then we can talk about an
architecture for providing them.
>From: Tony Coates <Tony.Coates@reuters.com>
>On 24/04/2001 07:06:48 Rick Jelliffe wrote:
> >Merely saying "XML Schemas bad! RELAX good!" keeps the cart before the
> >horse. If there is no modularity or ability to plug-n-play with
> >kinds of schema, then every little engineering trade-off has to be
> >to exhaustive discussion (as in XML Schemas) with no guarantee that the
> >result will satisfy everyone.
>Agreed. What would help us more is a validation API that allows pluggable
>validators, and that allows (multiple) validation of any part of an XML
>document, not just the whole document. If your Schema wraps a legacy DTD,
>shouldn't the legacy tags be validated using the DTD? If you have
>code in your application (and there is always some, doing the things that
>DTDs/Schemas can't do), separate it out and build your own pluggable
>That will make your application architecture cleaner.
>My major concern in achieving this is that Schemas can be applied to a DOM
>(which is very nice), but I'm not sure what tricks there might be in trying
>do the same with DTDs, which were not designed with that in mind. Of
>you would want not just these two, but also TREX/RELAX, Schematron, and any
>other likely suspects that might come along.
>All of this said, is anyone else interested in being able to do this kind
>thing, or is it all too hard? My impression is that for a lot of the
>DTDs are the now, XML Schemas will do what most people need for the future
>(remembering that most people aren't on the "xml-dev" list ...), and
>else tends to be marginalised as a toy for XML weenies. The existence of a
>API could change that (just as SAX and DOM made XML parsers accessible and
>acceptable by removing the lock-in), but I'm interested to know whether the
>of you see things the same way. All comments gratefully received.
>Anthony B. Coates
>Leader of XML Architecture & Design
>Chief Technology Office
>Reuters Plc, London.
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