The environment is WAS 6.1 on Linux, deploying a webapp that uses classes from xercesImpl.jar.
Due to company policy restrictions, the app must be deployed with settings:
Class Loader Order
Classes loaded with parent class loader first
-> Classes loaded with application class loader first
WAR class loader policy
Class loader for each WAR file in application
-> Single class loader for application
The WAR file contains a copy of xercesImpl.jar, the same one that was in the classpath when the app was compiled.
When launching the webapp, when Spring tries to parse its configs, it throws:
java.lang.VerifyError: class loading constraint violated
(class: org/apache/xerces/jaxp/DocumentBuilderImpl
method: parse(Lorg/xml/sax/InputSource;)Lorg/w3c/dom/Document;)
ANALYSIS SO FAR
It appears that WAS provides an implementation of
org.apache.xerces.jaxp.DocumentBuilderImpl, because we can remove
xercesImpl.jar from the WAR file and still get the same error (not
ClassNotFoundException). Thus WAS seems to be resolving the references
using its own copy that is incompatible with the references in our
compiled class files. However, the only other instance of 'xercesImpl.jar'
I can find (other than the copy deployed with our app) is in directory
deploytool, which seems to be outside the app server.
I scanned all the jars in WAS (all 1300 of them) with
for i in `find . -name \*.jar`; do jar tvf $i|grep -qi xerces && echo $i ; done
and found that ./java/jre/lib/xml.jar contains all the classes in org.apache.xerces.*,
so this is likely where the classloader is resolving the reference.
HERE'S THE WEIRD PART:
If we change to "parent class loader first" we do not see the exception. This goes counter to the expected behavior. We would expect that with "application cl