Xerces-J XSD 1.1 update: bug fixes and enhancements

The Xerces-J team did few enhancements to the XSD 1.1 implementation, which solves few important XSD namespace URI issues, which affected Xerces assertions and Conditional Type Alternatives (CTA) implementation. These changes went into the Xerces-J SVN repository today.

Here are the summary of these improvements:
1) There is now an ability with Xerces-J XSD 1.1 implementation, to pass on the XSD language namespace prefix (which is declared on the XSD <schema> element), along with the XSD language URI as a prefix-URI binding pair to PsychoPath XPath 2.0 engine. This enhancement allows, the XSD language prefix declared on the "XSD 1.1 Schema instance" 's <schema> element to be used in the assertions and CTA XPath 2.0 expressions, for example as following:

  <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" ...>
    ...
    <xs:assert test="xs:string(test) eq 'xxx'" />
    ...
  </xs:schema>

OR say,

  <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" ...>
    ...
    <xsd:assert test="xsd:string(test) eq 'xxx'" />
    ...
  </xsd:schema>

The earlier code in Xerces SVN (before the today's commit), hardcoded the XML Schema prefix to string, "xs" while communicating to the PsychoPath XPath 2 engine interface. That didn't allow the XPath 2 expressions in assertions and CTA to evaluate correctly (the Xerces code before this fix, always returned false for assertions, due to the presence of this bug), which used any other XSD prefix, like say "xsd" (even if the prefix "xsd" was bound to the XSD namespace, on the XSD root element, <schema>).

This was a significant Xerces assertions and CTA bug, which got solved today, and the fix for this is now available on the Xerces-J XSD 1.1 development SVN repository.

2) Another enhancement which went into Xerces-J SVN repository today, is the ability to specify the XPath 2.0 F&O namespace declaration on the XSD document root element, <schema>.

This enhancement makes possible something like, the following XSD 1.1 Schema to become valid:

  <xs:schema xmlns:xs="" xmlns:fn="http://www.w3.org/2005/xpath-functions" ...>
    ...
     <xs:assert test="xs:string(test) eq fn:string('xxx')" />
    ...
  </xs:schema>

Here the XML Schema author can, qualify the XPath 2 function calls in assertions XPath expressions, with the XPath 2 F&O namespace prefix, like fn:string('xxx') above. The F&O namespace prefix must be bound to the F&O namespace URI, "http://www.w3.org/2005/xpath-functions" for such a XSD Schema to be valid.

Even the following XSD 1.1 Schema is also valid (this happened to work correctly, earlier also before this Xerces SVN commit):

  <xs:schema xmlns:xs="" ...>
    ...
     <xs:assert test="xs:string(test) eq string('xxx')" />
    ...
  </xs:schema>

Here the XML Schema author, can use XPath 2 functions in Xerces assertions without specifying any prefix, for example like string('xxx') in the above example. The XPath 2 function calls without specifying the XPath 2 F&O prefix, would work correctly for all the XPath 2.0 built in functions, in Xerces assertions XPath 2 expressions.