Tips when using AWS sdk with JBoss AS + GateIn

While working on a really cool portlet for GateIn that uses Quartz scheduler and AWS sdk which I am going to unveil to the rest of the world in few days ;-), I came across a weird problem. :


Caused by: java.lang.LinkageError: loader constraint violation: when resolving interface method "javax.xml.xpath.XPath.setNamespaceContext(Ljavax/xml/namespace/NamespaceContext;)V" the class loader (instance of org/jboss/classloader/spi/base/BaseClassLoader) of the current class, org/quartz/xml/XMLSchedulingDataProcessor, and the class loader (instance of ) for resolved class, javax/xml/xpath/XPath, have different Class objects for the type javax/xml/namespace/NamespaceContext used in the signature


This kind of error obviously suggests some conflict with classloader and that was the case in this scenario too. I initially thought it must be something with quartz because I am using Quartz's XMLSchedulingDataProcessorPlugin but looks like that dependency comes from AWS sdk. To get it working, I simply removed stax-api-1.0.1.jar from WAR file and portlet deployed fine. The conflict happens because GateIn 3.0.1.GA + JBoss AS 5 combination has stax-api.jar under GateIn-3.1.0-GA/lib/endorsed which means StAX library is a system-wide library.