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Re: ANN: SAX Filters for Namespace Processing

• From: Peter Piatko <piatko@r...>
• To: xml-dev@l...
• Date: Tue, 31 Jul 2001 18:14:44 -0400

Hi,

I browsed through the doc and had a quick question.  Consider your example
doc:

<p:person xmlns:p="http://simonstl.com/person">
  <givenName>Chip</givenName>
  <familyName>Skillet</familyName>
  <address>
    <city>Ithaca</city>
  </address>
</p:person>

Suppose the definition of this doc was written in XML Schema.  Since XML
Schema can import namespaces, couldn't a correctly qualified version of the
doc look like this:

<p:person xmlns:p="http://simonstl.com/person"
                xmlns:a="http://simonstl.com/address">
  <p:givenName>Chip</p:givenName>
  <p:familyName>Skillet</p:familyName>
  <p:address>
    <a:city>Ithaca</a:city>
  </p:address>
</p:person>

(note that city is a different namespace).  The idea here is that the
address element is of a type that was imported from another namespace.  I'd
include the example schemas, but I am on my way home and don't have the
time. (Now I am beginning to hope that this message makes some sense ... :)

Regardless, some of the subelements might actually be from different
namespaces.  Do you have rules for dealing with this?  Are you going to tell
me to read the documentation more carefully? :-)

Thanks,

Peter Piatko

----- Original Message -----
From: "Simon St.Laurent" <simonstl@s...>
To: <xml-dev@l...>
Sent: Monday, July 30, 2001 8:35 PM
Subject: ANN: SAX Filters for Namespace Processing


> Last week at XTech (part of the O'Reilly Open Source Conference), Aaron
> Skonnard gave an excellent presentation on Namespaces.  He brought up a
> couple of issues which continue to bother me, but which have pretty much
> no single (imposable) solution.
>
> The first problem was the case of unqualified elements inside of
> namespace-qualified elements:
> <p:person xmlns:p="http://simonstl.com/person">
> <givenName>Chip</givenName>
> <familyName>Skillet</familyName>
> </p:person>
>
> I'd really prefer to see things like this written as:
> <p:person xmlns:p="http://simonstl.com/person">
> <p:givenName>Chip</p:givenName>
> <p:familyName>Skillet</p:familyName>
> </p:person>
>
> So, I wondered, why not write a filter that would convert from the first
> form to the second form?
>
> The other case involves unqualified attributes.  It's clear that the
> default namespace does not apply to attributes, but unqualified
> attributes remain somewhat anomalous themselves, not part of the element
> containing them but not necessarily a participant in the namespace.
> Things like:
>
> <p:person givenName="Chip" familyName="Skillet" />
>
> While I'm not as troubled by this as by the element issue, there are
> times (notably in RDF) where it's clearer to say:
> <p:person p:givenName="Chip" p:familyName="Skillet" />
>
> So again, why not write a filter?  (Thanks to Leigh Dodds for a push on
> this.)
>
> The two problems are very similar, and the code for the two filters is
> only slightly different.  They share a simple pair of classes for
> storing rules, and the code for the two is only slightly different.
>
> More details, and version 0.01 of the filters, is available at:
> http://simonstl.com/projects/namespace/docs
>
> This is a version 0.01, but the code is simple enough that the odds are
> good it's a solid foundation.  (Yes, I need to work on more unit
> testing.)  Version 0.02 will include RDDL documents at all the
> namespaces used.
>
> Also, I'm developing these filters and the Regular Fragmentations
> filters as rule-based tools running from XML vocabularies.  I'm hoping
> to modify the rule-loaders to be SAX filters, which would permit the
> combination of multiple rule sets into single documents read at a single
> parse.
>
> Simon St.Laurent
> Associate Editor
> O'Reilly & Associates
>
>
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