Thanks for information. The idea of dynamically change WS URL is based on this problem:
my application is an event-processor that receive a stream of events in input (by a jms <service> published via tuscany) and sends intercepted events in output via WebService to an external system. The WSDL of this external service is fixed and defined but the user can configure a different endpoint url by a configuration API of the system. Without using a tuscany reference, I've to create in my system a webservice client in any technology from scratch. My idea is that using Tuscany allow to obtain a webservice client without writing too much code, using a <reference> with a dynamic endpoint. About your comment, probably it is an incorrect interpretation of SCA. By the way, I'm using version 1.5.
