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[Bug 2825] RQ-154 Versioning support (versioning)

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Date: Thu, 02 Aug 2007 00:25:51 +0000
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To: www-xml-schema-comments@w3.org
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http://www.w3.org/Bugs/Public/show_bug.cgi?id=2825


cmsmcq@w3.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |ASSIGNED
           Keywords|needsAgreement              |needsDrafting




------- Comment #3 from cmsmcq@w3.org  2007-08-02 00:25 -------
At the WG's face to face meeting in June 2007 we discussed this issue
(RQ-154 Versioning support, in particular forward processing of XSDL)
and agreed to continue working on it.  On the telcon of 13 July
(http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2007Jul/att-0010/2007-07-13telcon.html)
[member-only link], the WG reached substantive ('phase-1') agreement on
a forward-processing proposal relying not on an xsd:fallback element
but on minVersion and maxVersion attributes.

The basic idea is that when schema documents are read, they are first
pre-processed by being examined for attributes named xvc:minVersion
and xvc:maxVersion (the names, especially the namespace, is subject to
change).  Each is treated as if declared with type xsd:decimal, and 
the value is compared to a decimal value representing the XSDL version
of the schema processor, which I'll represent as "$version".  If
$version < @xvc:minVersion or $version > @xvc:maxVersion, then the
attribute's parent element is suppressed.  For example:

  <xsd:complexType xvc:minVersion="1.1">
   <!--* definition suitable for 1.1 and later processors *-->
   ...
  </xsd:complexType> 
  <xsd:complexType xvc:maxVersion="1.0">
   <!--* definition suitable for 1.0 processors *-->
   ...
  </xsd:complexType> 

In this example, two versions of a complex type definition are
supplied, one for 1.0 processors and one for 1.1 and later
processors.

It may be noted that 1.0 processors can be retrofitted with this 
mechanism, and that in some cases users of 1.0 processors which have
not been retrofitted will be able to perform the preprocessing
manually, or to arrange for the environment (e.g. a caching proxy)
to perform it.

The conformance rules governing schema documents are intended to
apply to the schema document AFTER this preprocessing, not before
it.

A wording proposal is being prepared; I am changing the status keyword
accordingly.
Received on Thursday, 2 August 2007 00:26:03 UTC

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