XML Processing (was RE: Internationalization and naming)

Simon St.Laurent simonstl at simonstl.com
Mon Jan 4 21:43:25 GMT 1999

At 04:22 PM 1/4/99 -0500, david at megginson.com wrote:
>Andrew Layman writes:
> > I don't follow your point about a schema killing lightweight
> > processing.  Any sort of mapping--such as might be indicated in a
> > schema--would require obtaining the mapping rules and running a
> > processor.  And I also see that it would be useful to be able to
> > process a document without doing any mapping.  But would this not
> > be equally true of of any mapping scheme, whether AFs, mappings
> > packaged with schema, XSL-based or other?
>Absolutely correct -- what I mean by "light-weight" processing is
>processing a document without reference to an external schema.
>Namespaces do allow this, even though namespace processing itself is
>non-trivial; I'd suggest that any name-mapping scheme should do the
>same.  Simon's suggestion, as I recall, was to do the schema
>processing upstream (perhaps on the server side).

This discussion is setting off a lot of alarm bells for me, most of which
go off periodically anyway.

I really wish that the XML spec had cleanly separated validation from
well-formedness checking, thereby encouraging a clean separation of parsing
a document (into events or a tree) from validating its structure.  This
would have made it a lot easier to accomodate both light-weight processing
(without a schema) and the use of schemas/validation at any point in the
processing of an XML document (before or after transformations of some kind).

I like David's suggestion of architectural forms for this application very
much; unfortunately, it's difficult in the current environment to perform
such a transformation and then perform validation/schema checking on the
results.  That transformation would have to allow translation before
validation if validation were important.  XML-Data's approach, of putting
the translation table into the schema, at least allows validation to
operate on the translated version.

If we don't separate the basic work of parsing from the more sophisticated
work of checking document structures, it's very difficult to do anything to
a document before feeding it into the structure check.  In most
circumstances, perhaps, this doesn't matter, but in others it's a pain in
the neck.

I'd love to see a validator that works on a DOM tree or SAX events separate
from the parser itself.  If only I had the time to write one...

Simon St.Laurent
XML: A Primer / Cookies
Sharing Bandwidth 
Building XML Applications (February)

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