I created one simple webservice using Jaxws in eclipse and I am using JBOSS5.0 for deployment. After deploying, wsdl is getting published on server. I could create & run a Java POJO client to access the web service successfully, but whenever I am creating a web client for the webservice, I am getting errors. Below code is my webservice client: XYZService xyzService=new XYZService(); XYZ xyz=xyzService.getXYZPort(); out.println(xyz.sayHello("Welcome")); System.out.println(xyz.sayHello("Welcome")); Webservice: package com.sun.j2ee.blueprints.opc.powebservice; import javax.jws.WebMethod; import javax.jws.WebParam; import javax.jws.WebService; import javax.jws.soap.SOAPBinding; @WebService(name = "XYZ") @SOAPBinding ( style = SOAPBinding.Style.DOCUMENT, use = SOAPBinding.Use.LITERAL, parameterStyle = SOAPBinding.ParameterStyle.WRAPPED ) public class XYZ { @WebMethod public String sayHello(@WebParam(name = "name")String name) { return "Patni"+name; } } Following is the trace on the server console: 16:04:17,572 ERROR [[Sample]] Servlet.service() for servlet Sample threw exception java.lang.LinkageError: loader constraint violation: when resolving method "javax.xml.ws.Service.(Ljava/net/URL;Ljavax/xml/namespace/QName;)V" the class loader (instance of org/jboss/classloader/spi/base/BaseClassLoader) of the current class, com/sun/j2ee/blueprints/opc/powebservice/XYZService, and the class loader (instance of ) for resolved class, javax/xml/ws/Service, have different Class objects for the type javax/xml/namespace/QName used in the signature at com.sun.j2ee.blueprints.opc.powebservice.XYZService.(XYZService.java:41) at com.sun.j2ee.blueprints.opc.powebservice.Sample.service(Sample.java:32) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190) at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92) at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126) at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:828) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:601) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run(Thread.java:619) 16:15:40,784 ERROR [[Sample]] Servlet.service() for servlet Sample threw exception java.lang.LinkageError: loader constraint violation: when resolving method "javax.xml.ws.Service.(Ljava/net/URL;Ljavax/xml/namespace/QName;)V" the class loader (instance of org/jboss/classloader/spi/base/BaseClassLoader) of the current class, com/sun/j2ee/blueprints/opc/powebservice/XYZService, and the class loader (instance of ) for resolved class, javax/xml/ws/Service, have different Class objects for the type javax/xml/namespace/QName used in the signature at com.sun.j2ee.blueprints.opc.powebservice.XYZService.(XYZService.java:41) at com.sun.j2ee.blueprints.opc.powebservice.Sample.service(Sample.java:32) at javax.servlet.http.HttpServlet.service(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190) at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92) at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126) at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:828) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:601) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run(Thread.java:619) Please help me in resolving the error.. 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