[jboss-jira] [JBoss JIRA] Reopened: (JBAS-8417) Issue with loading JAXB library in JBOSS 4.3.0 with JDK6

Issue with loading JAXB library in JBOSS 4.3.0 with JDK6 -------------------------------------------------------- Key: JBAS-8417 URL: https://issues.jboss.org/browse/JBAS-8417 Project: Legacy JBoss Application Server 6 Issue Type: Bug Security Level: Public(Everyone can see) Components: ClassLoading Affects Versions: JBossAS-4.2.1.GA Environment: I am currently running JBoss 4.3.0 CP06 which I understand is essentially 4.2.1. Reporter: Pek Lee Seow Assignee: Scott Stark Priority: Critical Fix For: No Release I am having ClassCastException when instantiating JAXBContext within my web application. javax.xml.bind.JAXBException: ClassCastException: attempting to cast jar:file:/C:/Documentum/jboss4.3.0/server/DctmServer_MethodServer/deploy/dfs.ear/APP-INF/lib/jaxb-api.jar!/javax/xml/bind/JAXBContext.class to jar:file:/C:/Documentum/jboss4.3.0/jdk/jre/lib/rt.jar!/javax/xml/bind/JAXBContext.class. Please make sure that you are specifying the proper ClassLoader. javax.xml.bind.ContextFinder.handleClassCastException(ContextFinder.java:96) javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:205) javax.xml.bind.ContextFinder.find(ContextFinder.java:363) javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:574) javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:522) HelloWorldServlet.marshallCode(HelloWorldServlet.java:62) HelloWorldServlet.doGet(HelloWorldServlet.java:43) javax.servlet.http.HttpServlet.service(HttpServlet.java:617) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) Here is the line of code where the problem occurs: JAXBContext dataContext = JAXBContext.newInstance(MySimpleSouceData.class); Basically my web application (WAR) is deployed as part of an .EAR file with jaxb-api.jar and jaxb-impl.jar included in the .ear's APP-INF/lib. The web application does not have any of the JAXB libraries included in the .war file. The jboss-app.xml has been set to as follows: <?xml version="1.0" encoding="UTF-8"?> <jboss-app> <loader-repository> com.emc.documentum.fs:loader=emc-dfs.ear <loader-repository-config> java2ParentDelegation=false </loader-repository-config> </loader-repository> <library-directory> APP-INF/lib </library-directory> </jboss-app> I do not understand why the JAXBContext class instance from rt.jar (loaded by bootstrap/system classloader) is reference here when the configuration explicitly state to use the web application instance first (i.e. java2ParentDelegation=false). When I remove the jboss-app.xml file, the ClassCastException goes away. It seems the JAXBContext class is loaded by: org.jboss.mx.loading.UnifiedClassLoader3@2a2cc{ url=file:/C:/Documentum/jboss4.3.0/server/DctmServer_MethodServer/deploy/jbossws.sar/ ,addedOrder=12} Is this a JBoss classloading bug? What actually happens when jboss-app.xml is not provided? What is the default behaviour? And how is it that ClassCastException does not happen here??