i set up a web service for the existing code which access the oracle9i database, and the web service is running, because when i can get the xml schema which is enclosed with the issue, when i test the web service, i found it doesn't work for any function in the web service, when i invoke the findall function(the read way from db), the error info is the below: Exception in thread "main" org.codehaus.xfire.XFireRuntimeException: Could not invoke service.. Nested exception is org.codehaus.xfire.fault.XFireFault: Fault: java.lang.NullPointerException org.codehaus.xfire.fault.XFireFault: Fault: java.lang.NullPointerException at org.codehaus.xfire.fault.Soap11FaultSerializer.readMessage(Soap11FaultSerializer.java:31) at org.codehaus.xfire.fault.SoapFaultSerializer.readMessage(SoapFaultSerializer.java:28) at org.codehaus.xfire.soap.handler.ReadHeadersHandler.checkForFault(ReadHeadersHandler.java:111) at org.codehaus.xfire.soap.handler.ReadHeadersHandler.invoke(ReadHeadersHandler.java:67) at org.codehaus.xfire.handler.HandlerPipeline.invoke(HandlerPipeline.java:131) at org.codehaus.xfire.client.Client.onReceive(Client.java:382) at org.codehaus.xfire.transport.http.HttpChannel.sendViaClient(HttpChannel.java:139) at org.codehaus.xfire.transport.http.HttpChannel.send(HttpChannel.java:48) at org.codehaus.xfire.handler.OutMessageSender.invoke(OutMessageSender.java:26) at org.codehaus.xfire.handler.HandlerPipeline.invoke(HandlerPipeline.java:131) at org.codehaus.xfire.client.Invocation.invoke(Invocation.java:75) at org.codehaus.xfire.client.Client.invoke(Client.java:335) at org.codehaus.xfire.client.XFireProxy.handleRequest(XFireProxy.java:77) at org.codehaus.xfire.client.XFireProxy.invoke(XFireProxy.java:57) at $Proxy0.findall(Unknown Source) at core.web.callWstst.coreCallWsTst.main(coreCallWsTst.java:37) and when i test the create function(it write the db), the error info shows : Exception in thread "main" org.codehaus.xfire.XFireRuntimeException: Could not invoke service.. Nested exception is org.codehaus.xfire.fault.XFireFault: No write method for property {http://data.api.core.celadon.com}corTransaction in class com.celadon.core.api.data.TransactionData org.codehaus.xfire.fault.XFireFault: No write method for property {http://data.api.core.celadon.com}corTransaction in class com.celadon.core.api.data.TransactionData at org.codehaus.xfire.fault.Soap11FaultSerializer.readMessage(Soap11FaultSerializer.java:31) at org.codehaus.xfire.fault.SoapFaultSerializer.readMessage(SoapFaultSerializer.java:28) at org.codehaus.xfire.soap.handler.ReadHeadersHandler.checkForFault(ReadHeadersHandler.java:111) at org.codehaus.xfire.soap.handler.ReadHeadersHandler.invoke(ReadHeadersHandler.java:67) at org.codehaus.xfire.handler.HandlerPipeline.invoke(HandlerPipeline.java:131) at org.codehaus.xfire.client.Client.onReceive(Client.java:382) at org.codehaus.xfire.transport.http.HttpChannel.sendViaClient(HttpChannel.java:139) at org.codehaus.xfire.transport.http.HttpChannel.send(HttpChannel.java:48) at org.codehaus.xfire.handler.OutMessageSender.invoke(OutMessageSender.java:26) at org.codehaus.xfire.handler.HandlerPipeline.invoke(HandlerPipeline.java:131) at org.codehaus.xfire.client.Invocation.invoke(Invocation.java:75) at org.codehaus.xfire.client.Client.invoke(Client.java:335) at org.codehaus.xfire.client.XFireProxy.handleRequest(XFireProxy.java:77) at org.codehaus.xfire.client.XFireProxy.invoke(XFireProxy.java:57) at $Proxy0.create(Unknown Source) at serverCoreTst.main(serverCoreTst.java:39) would you please give me some reasonable explanation, any suggestion will be appreciated