The actual standards for service authoring, composition and development are not easy to port and to apply for next generation mobile applications. This paper describes some tools that we?re developing in the context of the IST-Simple Mobile Service project, whose aim is to ease the authoring and the use of services for mobile devices. We propose a service composition approach using an UML profile very close to the actual standards for Web Services definition and authoring, like WSDL and BPEL. We take a glance at SMILE, the run-time support we provide for service execution. Finally we hint at an efficient serialization mechanism based on JSON, a human readable data exchange format less verbose and, in our opinion, more suitable for mobile terminals than XML.