I have had good success using Spring WS for the client end of a web service app - see http://static.springsource.org/spring-ws/sites/1.5/reference/html/client.html
My project uses a combination of:
XMLBeans (generated from a simple Maven job using the xmlbeans-maven-plugin)
Spring WS - using marshalSendAndReceive() reduces the code down to one line for sending and receiving
some Dozer - mapping the complex XMLBeans to simple beans for the client GUI