If you use the builtin JAX-WS implementation and want to see the SOAP requests and responses, you have to turn on the “dump” option in the transport pipe.
The system property to set depends on your Java version.
com.sun.xml.ws.transport.http.client.HttpTransportPipe.dump=true com.sun.xml.internal.ws.transport.http.client.HttpTransportPipe.dump=true com.sun.xml.ws.transport.http.HttpAdapter.dump=true com.sun.xml.internal.ws.transport.http.HttpAdapter.dump=true
The most common option seems to be com.sun.xml.internal.ws.transport.http.client.HttpTransportPipe.dump.
To use it, add the following to yout JVM arguments (e.g. to the command line):
-Dcom.sun.xml.internal.ws.transport.http.client.HttpTransportPipe.dump=true
Java 8 on OS X needs this:
-Dcom.sun.xml.ws.transport.http.client.HttpTransportPipe.dump=true