Abstract-- In the proxy approach to Service Oriented Computing, a service advertises a proxy, which is searched for, retrieved and used by interested clients as a local handle to the service process that runs on a remote host. Due to software evolution, it becomes necessary at times to upgrade the service. Some of these upgrades may require an upgrade of the proxy software, in addition to the server itself. This paper addresses the issue of upgrading both the server and its proxy in a manner transparent to the client, and ensures only momentary interruption during the switching process. The model we propose is designed for ad hoc wireless networks, but can be used in other settings as well. We also describe a Java implementation of our model.