If you are using Tomcat 7.x and Servlet 3.0, the listener com.sun.xml.ws.transport.http.servlet.WSServletContextListener
is dynamically loaded. Since Java EE 6, a new component was added: javax.servlet.ServletContainerInitializer
Interface which allows a library/runtime to be notified of a web application's startup phase and perform any required programmatic registration of servlets, filters, and listeners in response to it.
The file jaxws-rt.jar contains in \META-INF\services
a simple file text named javax.servlet.ServletContainerInitializer
with one line:
com.sun.xml.ws.transport.http.servlet.WSServletContainerInitializer
This is the fully qualified class name which loads the required listener.