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From Army <qoz...@gmail.com>
Subject Re: svn commit: r543183 - in /db/derby/code/trunk/java: engine/org/apache/derby/impl/sql/compile/UnaryOperatorNode.java testing/org/apache/derbyTesting/functionTests/tests/lang/CollationTest.java
Date Thu, 31 May 2007 21:50:58 GMT
Daniel John Debrunner wrote:
> I thought there were standard apis to the Xpath engine or is that just 
> for the XML parser?

It looks there's a standard API for XPath as of 1.5, encapsulated in the 
javax.xml.xpath.* package.  But that package does not exist for 1.4 (which is 
what the initial XML support was catering to).

As for the XML parser, Yes, the standard API for that exists in 1.4 and Derby 
currently uses it.  That's what the "JAXP" stuff is all about.  So Derby works 
in any environment where it can find a JAXP parser.  Xerces is the Apache parser 
which satisfies the API, and Xerces is embedded within the more recent JVMs. 
But it is not a requirement; a user could, for example, put the Crimson parser 
in his/her classpath and Derby would still run correctly using that.

Xalan, however, is a different story.  There was no Java standard XPath API when 
Derby XML came out (to my knowledge...), so Derby has specific dependencies on 
the Xalan package.  Unlike Xerces, Xalan cannot be swapped out unless the Derby 
code is itself changed.


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