I have WSDL which defines an asynchronous message. The port type and wsdl operation do not define any output as in the following extract: <wsdl:portType name="RequestInbound"> <wsdl:operation name="RequestInbound"> <wsdl:input message="p11.PickingRequestIn" /> </wsdl:operation> </wsdl:portType> <wsdl:binding name="RequestInboundBinding" type="p1:RequestInbound" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/"> <soap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" /> <wsdl:operation name="RequestInbound"> <soap:operation soapAction="http://sap.com/xi/WebService/soap1.1" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" /> <wsdl:input> <soap:body use="literal" xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/" /> </wsdl:input> </wsdl:operation> </wsdl:binding> When I use this WSDL to create a SOAP service using cxf wsdl2java it creates a class with a @OneWay annotatation for the method. @SOAPBinding(parameterStyle = SOAPBinding.ParameterStyle.BARE) @Oneway @WebMethod(operationName = "RequestInbound", action = "http://sap.com/xi/WebService/soap1.1") public void requestInbound( @WebParam(partName = "RequestIn", name = "RequestIn", targetNamespace = "urn:pnp:eiss:im") RequestIn requestIn ); I have my service defined as follows: <service name="DeliveryRequestService"> <inbound> <inbound-endpoint address="cxf:http://localhost:8777/esb/DeliveryRequestService" synchronous="true"/> </inbound> <component> <singleton-object class="request.RequestInboundImpl" /> </component> </service> When I call the webservice, the method runs but while writing the reponse back to the client I get the following exception: [10-01 15:36:22] ERROR DefaultExceptionStrategy [connector.http.0.receiver.2]: Caught exception in Exception Strategy: null java.lang.NullPointerException at org.mule.transport.cxf.CxfServiceComponent$1.write(CxfServiceComponent.j ava:272) at org.mule.transport.http.HttpServerConnection.writeResponse(HttpServerCon nection.java:281) at org.mule.transport.http.HttpMessageReceiver$HttpWorker.run(HttpMessageRe ceiver.java:189) at org.mule.work.WorkerContext.run(WorkerContext.java:310) at edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor.runWor ker(ThreadPoolExecutor.java:1061) at edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor$Worker .run(ThreadPoolExecutor.java:575) at java.lang.Thread.run(Unknown Source) Mule sends a result back but the Content Type in the HTTP header is set to text/plain.