A mobile device stores a service-creation application and presents, via the service-creation application, a user interface to solicit a service definition for client mobile devices. The mobile device stores a service-engine for providing the service and announces availability of the service to the client mobile devices. The mobile device receives, in response to the announcing, a registration request from one of the client mobile devices and validates the registration request. The mobile device then provides, to the one of the client mobile devices, the service via the service engine.