CommonBinding binding = (CommonBinding)bindingProvider.getCommonBinding();
EndpointInvocation epInv = new EndpointInvocation(opMetaData);
epInv.initInputParams(new Object[]{"Hello World!", "hi"});
SOAPMessage reqMessage = (SOAPMessage)binding.bindRequestMessage(opMetaData, epInv, null);
ByteArrayOutputStream stream = new ByteArrayOutputStream();
reqMessage.saveChanges();
reqMessage.writeTo(stream);