If you mean that you need something extra to convert the XML message (SOAP message) to Java object and viceversa, you don't.
JAX-WS converts the incoming SOAP message (actually a XML request) to Java object. And transforms the Java objects to XML response for send to the web service client.
(source: anyframejava.org)
The conversion in both directions is performed by JAXB.
See more in Developing Web Services Applications.