In requesting a server (17) to provide a service to a user, a user application (21) provides a service request that includes first information which directs the server to route to the user application a data stream associated with the service. The first information is transformed (123) into second information which directs the server to route the data stream to a proxy (33, 34) which is installed in a communication path (27) from the server to the user application and which is operable for performing a proxy operation on the data stream.