title: WebSphere 8: el-api.jar (in app) conflicts with javax.j2ee.el.jar (in WS)
body: <p>In short: is there a way to tell WebSphere to use classes from the application's own el-api.jar instead of from (the built-in) javax.j2ee.el.jar?</p>
  
  <p>Story:
  I know there are discussions on the internet about this problem during migrating applications from WAS 6.1 to WAS 8, but neither of them mentions explicitly this point:</p>
  
  <p>The whole thing gets stuck when WAS 8 tries to load javax.el.ExpressionFactory from el-api.jar (included in the EAR). At this point, however, it has already loaded it from javax.j2ee.el.jar. (Which didn't exist in WAS 6.1.) If you switch on verbose class loading:</p>
  
  <p>class load: javax.el.ExpressionFactory from: file:/C:/Program Files/IBM/WebSphere/AppServer/plugins/javax.j2ee.el.jar
  (BEFORE you would even install the application!)</p>
  
  <p>It seems, since this latter jar is already loaded before one would install the EAR of the application containing el-api.jar, WAS 8 stumbles upon a class loading conflict, regardless of whether you've specified for it to use the PARENT_LAST class loading strategy or not.</p>
  
  <p>I can compile and install the application by using javax.j2ee.el.jar instead of el-api.jar in it, but on the one hand I'm not aware of what long-term consequences this might have (I haven't been able to get it running either way so far), on the other hand the ultimate goal would be to be able to install the original EAR (containing its own JSF libraries etc.) on the WAS 8 server with as few modifications as possible.</p>
  
  <p>Is there a way to tell the WAS 8 server to reload the possibly conflicting classes in the application from el-api.jar or even not to load javax.j2ee.el.jar in the first place? (Like I mentioned, specifying PARENT_CLASS doesn't have any effect on this.)</p>
  
  <p>Thanks.</p>
  
  <p>The exception by the way that is thrown when WAS 8 tries to load javax.el.ExpressionFactory from el-api.jar (when starting the installed application):</p>
  
  <p>(Sorry that it's in German, some googling identifies the Eglish version of this error message as:</p>
  
  <pre><code>'java.lang.LinkageError: loading constraint violation: loader "com/ibm/ws/classloader/CompoundClassLoader@1ef123a" previously initiated loading for a different type with name "javax/el/ExpressionFactory" defined by loader org/eclipse/osgi/internal/baseadaptor/DefaultClassLoader@1f75d64"')
  
  java.lang.LinkageError: Übertretung der Ladeeinschränkung: Ladeprogramm "com/ibm/ws/classloader/CompoundClassLoader@1ef123a" hat zuvor das Laden für einen anderen Typ mit dem Namen "javax/el/ExpressionFactory", der durch Ladeprogramm "org/eclipse/osgi/internal/baseadaptor/DefaultClassLoader@1f75d64" definiert ist, eingeleitet.
  at java.lang.ClassLoader.defineClassImpl(Native Method)
  at java.lang.ClassLoader.defineClass(ClassLoader.java:262)
  at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:69)
  at com.ibm.ws.classloader.CompoundClassLoader._defineClass(CompoundClassLoader.java:829)
  at com.ibm.ws.classloader.CompoundClassLoader.localFindClass(CompoundClassLoader.java:744)
  at com.ibm.ws.classloader.CompoundClassLoader.loadClass(CompoundClassLoader.java:585)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:627)
  at java.lang.Class.getDeclaredFieldsImpl(Native Method)
  at java.lang.Class.getDeclaredFields(Class.java:546)
  at com.ibm.ffdc.util.formatting.Introspector$1.run(Introspector.java:138)
  at com.ibm.ffdc.util.formatting.Introspector$1.run(Introspector.java:136)
  at java.security.AccessController.doPrivileged(AccessController.java:254)
  at com.ibm.ffdc.util.formatting.Introspector.getDeclaredFields(Introspector.java:135)
  at com.ibm.ffdc.util.formatting.Introspector.formatTo(Introspector.java:94)
  at com.ibm.ffdc.util.provider.IncidentStream$2.writeTo(IncidentStream.java:194)
  at com.ibm.ffdc.util.provider.IncidentStream.write(IncidentStream.java:198)
  at com.ibm.ffdc.util.provider.IncidentStream.write(IncidentStream.java:129)
  at com.ibm.ffdc.util.formatting.JavaUtilFormatter.formatTo(JavaUtilFormatter.java:56)
  at com.ibm.ffdc.util.formatting.JavaUtilFormatter.formatTo(JavaUtilFormatter.java:42)
  at com.ibm.ffdc.util.provider.IncidentStream$2.writeTo(IncidentStream.java:194)
  at com.ibm.ffdc.util.provider.IncidentStream.write(IncidentStream.java:198)
  at com.ibm.ffdc.util.provider.IncidentStream.write(IncidentStream.java:129)
  at com.ibm.ffdc.util.formatting.Introspector.formatTo(Introspector.java:109)
  at com.ibm.ffdc.util.provider.IncidentStream$2.writeTo(IncidentStream.java:194)
  at com.ibm.ffdc.util.provider.IncidentStream.write(IncidentStream.java:198)
  at com.ibm.ffdc.util.provider.IncidentStream.write(IncidentStream.java:129)
  at com.ibm.ws.ffdc.impl.DMAdapter.formatTo(DMAdapter.java:88)
  at com.ibm.ffdc.util.provider.IncidentLogger.writeIncidentTo(IncidentLogger.java:63)
  at com.ibm.ws.ffdc.impl.FfdcProvider.logIncident(FfdcProvider.java:205)
  at com.ibm.ws.ffdc.impl.FfdcProvider.logIncident(FfdcProvider.java:136)
  at com.ibm.ffdc.util.provider.FfdcProvider.log(FfdcProvider.java:251)
  at com.ibm.ws.ffdc.impl.FfdcProvider.log(FfdcProvider.java:149)
  at com.ibm.ffdc.util.provider.IncidentEntry.log(IncidentEntry.java:105)
  at com.ibm.ffdc.util.provider.Ffdc.log(Ffdc.java:94)
  at com.ibm.ws.ffdc.FFDCFilter.processException(FFDCFilter.java:114)
  at com.ibm.wsspi.webcontainer.util.FFDCWrapper.processException(FFDCWrapper.java:6)
  at com.ibm.ws.webcontainer.webapp.WebApp.notifyServletContextCreated(WebApp.java:1653)
  at com.ibm.ws.webcontainer.webapp.WebAppImpl.initialize(WebAppImpl.java:410)
  at com.ibm.ws.webcontainer.webapp.WebGroupImpl.addWebApplication(WebGroupImpl.java:88)
  at com.ibm.ws.webcontainer.VirtualHostImpl.addWebApplication(VirtualHostImpl.java:169)
  at com.ibm.ws.webcontainer.WSWebContainer.addWebApp(WSWebContainer.java:746)
  at com.ibm.ws.webcontainer.WSWebContainer.addWebApplication(WSWebContainer.java:634)
  at com.ibm.ws.webcontainer.component.WebContainerImpl.install(WebContainerImpl.java:422)
  at com.ibm.ws.webcontainer.component.WebContainerImpl.start(WebContainerImpl.java:714)
  at com.ibm.ws.runtime.component.ApplicationMgrImpl.start(ApplicationMgrImpl.java:1160)
  at com.ibm.ws.runtime.component.DeployedApplicationImpl.fireDeployedObjectStart(DeployedApplicationImpl.java:1369)
  at com.ibm.ws.runtime.component.DeployedModuleImpl.start(DeployedModuleImpl.java:638)
  at com.ibm.ws.runtime.component.DeployedApplicationImpl.start(DeployedApplicationImpl.java:967)
  at com.ibm.ws.runtime.component.ApplicationMgrImpl.startApplication(ApplicationMgrImpl.java:766)
  at com.ibm.ws.runtime.component.ApplicationMgrImpl.startApplicationDynamically(ApplicationMgrImpl.java:1354)
  at com.ibm.ws.runtime.component.ApplicationMgrImpl.start(ApplicationMgrImpl.java:2150)
  at com.ibm.ws.runtime.component.CompositionUnitMgrImpl.start(CompositionUnitMgrImpl.java:445)
  at com.ibm.ws.runtime.component.CompositionUnitImpl.start(CompositionUnitImpl.java:123)
  at com.ibm.ws.runtime.component.CompositionUnitMgrImpl.start(CompositionUnitMgrImpl.java:388)
  at com.ibm.ws.runtime.component.CompositionUnitMgrImpl.access$500(CompositionUnitMgrImpl.java:116)
  at com.ibm.ws.runtime.component.CompositionUnitMgrImpl$1.run(CompositionUnitMgrImpl.java:663)
  at com.ibm.ws.security.auth.ContextManagerImpl.runAs(ContextManagerImpl.java:5413)
  at com.ibm.ws.security.auth.ContextManagerImpl.runAsSystem(ContextManagerImpl.java:5539)
  at com.ibm.ws.security.core.SecurityContext.runAsSystem(SecurityContext.java:255)
  at com.ibm.ws.runtime.component.CompositionUnitMgrImpl.startCompositionUnit(CompositionUnitMgrImpl.java:677)
  at com.ibm.ws.runtime.component.CompositionUnitMgrImpl.startCompositionUnit(CompositionUnitMgrImpl.java:621)
  at com.ibm.ws.runtime.component.ApplicationMgrImpl.startApplication(ApplicationMgrImpl.java:1246)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:60)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
  at java.lang.reflect.Method.invoke(Method.java:611)
  at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:49)
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:60)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
  at java.lang.reflect.Method.invoke(Method.java:611)
  at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:256)
  at javax.management.modelmbean.RequiredModelMBean.invokeMethod(RequiredModelMBean.java:1085)
  at javax.management.modelmbean.RequiredModelMBean.invoke(RequiredModelMBean.java:966)
  at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:848)
  at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:773)
  at com.ibm.ws.management.AdminServiceImpl$1.run(AdminServiceImpl.java:1335)
  at com.ibm.ws.security.util.AccessController.doPrivileged(AccessController.java:118)
  at com.ibm.ws.management.AdminServiceImpl.invoke(AdminServiceImpl.java:1228)
  at com.ibm.ws.management.commands.AdminServiceCommands$InvokeCmd.execute(AdminServiceCommands.java:251)
  at com.ibm.ws.console.core.mbean.MBeanHelper.invoke(MBeanHelper.java:241)
  at com.ibm.ws.console.appdeployment.ApplicationDeploymentCollectionAction.execute(ApplicationDeploymentCollectionAction.java:564)
  at org.apache.struts.action.RequestProcessor.processActionPerform(Unknown Source)
  at org.apache.struts.action.RequestProcessor.process(Unknown Source)
  at org.apache.struts.action.ActionServlet.process(Unknown Source)
  at org.apache.struts.action.ActionServlet.doPost(Unknown Source)
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:595)
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:668)
  at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1214)
  at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:774)
  at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:456)
  at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:178)
  at com.ibm.ws.webcontainer.filter.WebAppFilterChain.invokeTarget(WebAppFilterChain.java:125)
  at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:77)
  at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:926)
  at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:1023)
  at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.dispatch(WebAppRequestDispatcher.java:1384)
  at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.forward(WebAppRequestDispatcher.java:193)
  at org.apache.struts.action.RequestProcessor.doForward(Unknown Source)
  at org.apache.struts.tiles.TilesRequestProcessor.doForward(Unknown Source)
  at org.apache.struts.action.RequestProcessor.processForwardConfig(Unknown Source)
  at org.apache.struts.tiles.TilesRequestProcessor.processForwardConfig(Unknown Source)
  at org.apache.struts.action.RequestProcessor.process(Unknown Source)
  at org.apache.struts.action.ActionServlet.process(Unknown Source)
  at org.apache.struts.action.ActionServlet.doPost(Unknown Source)
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:595)
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:668)
  at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1214)
  at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:774)
  at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:456)
  at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:178)
  at com.ibm.ws.webcontainer.filter.WebAppFilterChain.invokeTarget(WebAppFilterChain.java:125)
  at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:92)
  at com.ibm.ws.console.core.servlet.WSCUrlFilter.setUpCommandAssistance(WSCUrlFilter.java:950)
  at com.ibm.ws.console.core.servlet.WSCUrlFilter.continueStoringTaskState(WSCUrlFilter.java:499)
  at com.ibm.ws.console.core.servlet.WSCUrlFilter.doFilter(WSCUrlFilter.java:320)
  at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:192)
  at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:89)
  at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:926)
  at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:1023)
  at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:87)
  at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:895)
  at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1662)
  at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:195)
  at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:452)
  at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewRequest(HttpInboundLink.java:511)
  at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.processRequest(HttpInboundLink.java:305)
  at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:83)
  at com.ibm.ws.ssl.channel.impl.SSLReadServiceContext$SSLReadCompletedCallback.complete(SSLReadServiceContext.java:1784)
  at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
  at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
  at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
  at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:138)
  at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:204)
  at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:775)
  at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:905)
  at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1659)
  </code></pre>