12:58 p.m.
JBoss: 5.1.0.GA
JDK: 1.5.0_11-b03
OS: WinXP SP3
Hi,
I'm getting the dreaded ClassCastException when deploying my web app due to a conflict
between XercesImpl.jar bundled with JBoss and another one inside my war file:
| 13:00:45,353 INFO [TomcatDeployment] deploy, ctxPath=/nexj-web
| 13:00:45,462 ERROR [JBossContextConfig] XML error parsing: context.xml
| org.jboss.xb.binding.JBossXBRuntimeException: Failed to create a new SAX parser
| at
org.jboss.xb.binding.UnmarshallerFactory$UnmarshallerFactoryImpl.newUnmarshaller(UnmarshallerFactory.java:100)
| at
org.jboss.web.tomcat.service.deployers.JBossContextConfig.processContextConfig(JBossContextConfig.java:549)
| at
org.jboss.web.tomcat.service.deployers.JBossContextConfig.init(JBossContextConfig.java:536)
| at
org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:279)
| at
org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
| at org.apache.catalina.core.StandardContext.init(StandardContext.java:5436)
| at org.apache.catalina.core.StandardContext.start(StandardContext.java:4148)
| at
org.jboss.web.tomcat.service.deployers.TomcatDeployment.performDeployInternal(TomcatDeployment.java:310)
| at
org.jboss.web.tomcat.service.deployers.TomcatDeployment.performDeploy(TomcatDeployment.java:142)
| at
org.jboss.web.deployers.AbstractWarDeployment.start(AbstractWarDeployment.java:461)
| at org.jboss.web.deployers.WebModule.startModule(WebModule.java:118)
| at org.jboss.web.deployers.WebModule.start(WebModule.java:97)
| at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
| at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
| at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
| at java.lang.reflect.Method.invoke(Method.java:585)
| at
org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:157)
| at org.jboss.mx.server.Invocation.dispatch(Invocation.java:96)
| at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
| at
org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
| at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:668)
| at org.jboss.system.microcontainer.ServiceProxy.invoke(ServiceProxy.java:206)
| at $Proxy38.start(Unknown Source)
| at
org.jboss.system.microcontainer.StartStopLifecycleAction.installAction(StartStopLifecycleAction.java:42)
| at
org.jboss.system.microcontainer.StartStopLifecycleAction.installAction(StartStopLifecycleAction.java:37)
| at
org.jboss.dependency.plugins.action.SimpleControllerContextAction.simpleInstallAction(SimpleControllerContextAction.java:62)
| at
org.jboss.dependency.plugins.action.AccessControllerContextAction.install(AccessControllerContextAction.java:71)
| at
org.jboss.dependency.plugins.AbstractControllerContextActions.install(AbstractControllerContextActions.java:51)
| at
org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348)
| at
org.jboss.system.microcontainer.ServiceControllerContext.install(ServiceControllerContext.java:286)
| at
org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1631)
| at
org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:934)
| at
org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1082)
| at
org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:984)
| at
org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:822)
| at
org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:553)
| at org.jboss.system.ServiceController.doChange(ServiceController.java:688)
| at org.jboss.system.ServiceController.start(ServiceController.java:460)
| at org.jboss.system.deployers.ServiceDeployer.start(ServiceDeployer.java:163)
| at org.jboss.system.deployers.ServiceDeployer.deploy(ServiceDeployer.java:99)
| at org.jboss.system.deployers.ServiceDeployer.deploy(ServiceDeployer.java:46)
| at
org.jboss.deployers.spi.deployer.helpers.AbstractSimpleRealDeployer.internalDeploy(AbstractSimpleRealDeployer.java:62)
| at
org.jboss.deployers.spi.deployer.helpers.AbstractRealDeployer.deploy(AbstractRealDeployer.java:50)
| at
org.jboss.deployers.plugins.deployers.DeployerWrapper.deploy(DeployerWrapper.java:171)
| at
org.jboss.deployers.plugins.deployers.DeployersImpl.doDeploy(DeployersImpl.java:1439)
| at
org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:1157)
| at
org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:1178)
| at
org.jboss.deployers.plugins.deployers.DeployersImpl.install(DeployersImpl.java:1098)
| at
org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348)
| at
org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1631)
| at
org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:934)
| at
org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1082)
| at
org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:984)
| at
org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:822)
| at
org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:553)
| at
org.jboss.deployers.plugins.deployers.DeployersImpl.process(DeployersImpl.java:781)
| at
org.jboss.deployers.plugins.main.MainDeployerImpl.process(MainDeployerImpl.java:702)
| at
org.jboss.system.server.profileservice.repository.MainDeployerAdapter.process(MainDeployerAdapter.java:117)
| at
org.jboss.system.server.profileservice.repository.ProfileDeployAction.install(ProfileDeployAction.java:70)
| at
org.jboss.system.server.profileservice.repository.AbstractProfileAction.install(AbstractProfileAction.java:53)
| at
org.jboss.system.server.profileservice.repository.AbstractProfileService.install(AbstractProfileService.java:361)
| at
org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348)
| at
org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1631)
| at
org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:934)
| at
org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1082)
| at
org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:984)
| at
org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:822)
| at
org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:553)
| at
org.jboss.system.server.profileservice.repository.AbstractProfileService.activateProfile(AbstractProfileService.java:306)
| at
org.jboss.system.server.profileservice.ProfileServiceBootstrap.start(ProfileServiceBootstrap.java:271)
| at org.jboss.bootstrap.AbstractServerImpl.start(AbstractServerImpl.java:461)
| at org.jboss.Main.boot(Main.java:221)
| at org.jboss.Main$1.run(Main.java:556)
| at java.lang.Thread.run(Thread.java:595)
| Caused by: org.jboss.xb.binding.JBossXBException: Failed to create a new SAX parser
| at
org.jboss.xb.binding.parser.sax.SaxJBossXBParser.<init>(SaxJBossXBParser.java:97)
| at
org.jboss.xb.binding.UnmarshallerImpl.<init>(UnmarshallerImpl.java:56)
| at
org.jboss.xb.binding.UnmarshallerFactory$UnmarshallerFactoryImpl.newUnmarshaller(UnmarshallerFactory.java:96)
| ... 73 more
| Caused by: java.lang.ClassCastException:
org.apache.xerces.parsers.XIncludeAwareParserConfiguration
| at org.apache.xerces.parsers.SAXParser.<init>(SAXParser.java:99)
| at org.apache.xerces.parsers.SAXParser.<init>(SAXParser.java:84)
| at
org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.<init>(SAXParserImpl.java:364)
| at org.apache.xerces.jaxp.SAXParserImpl.<init>(SAXParserImpl.java:124)
| at
org.apache.xerces.jaxp.SAXParserFactoryImpl.newSAXParser(SAXParserFactoryImpl.java:76)
| at
org.jboss.xb.binding.parser.sax.SaxJBossXBParser.<init>(SaxJBossXBParser.java:92)
| ... 75 more
|
I've traced through the deployer and Xerces code and the Exception is happening for
the following reason:
- the deployer sets the context classloader to be the war classloader
- the deployer tries to create a parser to parse context.xml file, this is delegated to
xerces
- as part of initializing the parser, xerces does the following:
| (XMLParserConfiguration)ObjectFactory.createObject(
| "org.apache.xerces.xni.parser.XMLParserConfiguration",
| "org.apache.xerces.parsers.XIncludeAwareParserConfiguration")
|
- digging into the createObject() call, xerces uses the context classloader to load
XIncludeAwareParserConfiguration
- however, XMLParserConfiguration to which XIncludeAwareParserConfiguration is cast in the
above statement is loaded by the current classloader which is the deployer classloader
(jboss-web, I believe)
- thus the ClassCastException
Now, I can resolve this issue by following the instructions in
http://www.jboss.org/community/wiki/useJBossWebClassLoaderinJBoss5. However, neither of
the approaches there is acceptable since they both boil down to effectively removing the
XercesImpl.jar from my war. Both of those approaches force the war classloader to
delegate to parent first which essentially forces the JBoss bundled XercesImpl.jar to
always be used. In fact, if I follow this approach I get another (application specific)
Exception because my application relies on using the context classloader (i.e. the war
classloader) to load classes from the XercesImpl.jar inside my war. Additionally, I
don't really want to change the Servlet Spec classloading behaviour anyway.
I think the real problem is that the deployer sets the context classloader to the war
classloader before instantiating the parser. IMHO, I think the deployer should either do
this after it instantiates the parser or it should temporarily swap out the context
classloader and swap in the deployer classloader in its place. Incidently, in JBoss
4.0.5, the version from which I'm trying to upgrade to 5.1.0, there is no problem.
I've briefly looked at the 4.0.5 code and I believe that the tomcat deployer used to
deploy the war, indeed uses the deployer classloader to instantiate the parser and not the
war classloader.
Do I have a point or am I way off?
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