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

[Pek Lee Seow (JIRA)]

Issue with loading JAXB library in JBOSS 4.3.0 with JDK6
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                 Key: JBAS-8417
                 URL: https://jira.jboss.org/browse/JBAS-8417
             Project: JBoss Application Server
          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 M Stark
            Priority: Critical


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 at 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??

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