From: Russel Winder <russ...@concertant.com> To: Jochen Theodorou <blac...@gmx.org> Cc: Guillaume Laforge <glaf...@g2one.com> Subject: XML class lookup problem in Gant Date: Fri, 25 Apr 2008 08:08:30 +0100

Jochen,

I appreciate you are very busy but I think I need a little help with this one -- my lack of detailed knowledge of Groovy and Java class loader and class lookup is now open for all to see :-(

GANT-34 is an example of a java.lang.LinkageError that I have been looking at for a few days and just can't get my head around.

Code that works fine on Ubuntu 7.10, fails on Mac OS X and Solaris 10 with this error. The Mac OS X error message is not very informative:

java.lang.LinkageError: loader constraints violated when linking org/w3c/dom/Node class

the Solaris 10 error message is a little more informative:

java.lang.LinkageError: loader constraint violation in interface itable initialization: when resolving method "org.apache.xerces.dom.NodeImpl.item(I)Lorg/w3c/dom/Node;" the class loader (instance of org/codehaus/groovy/tools/RootLoader) of the current class, org/apache/xerces/dom/NodeImpl, and the class loader (instance of <bootloader>) for interface org/w3c/dom/NodeList have different Class objects for the type org/w3c/dom/Node used in the signature

So clearly this is a class lookup problem and there are multiple class loaders involved and rt.jar contains a set of the XML processing classes as do a huge number of other jars in and around the Java world, not least of which is xml-apis.jar.

And that is as far as I have got -- apart from thinking this is not a Gant problem but a Groovy problem.

One user reported the workaround of putting an additional version of xml-apis.jar into their classpath before running Gant, but this seems like a hack to me. If I could get a handle on the real problem, I can then release Gant 1.2.0 till then I am hesitant.