: The paper describes a mobile application for traffic telematics, based on the Jini middleware. The application is realized as a set of user-level services, characterized by following properties: The services should be proactive, i.e. they act on behalf of the user based on the user’s preferences. Secondly, context information derived from floating car data is used to improve the quality of the proactive service and thirdly, mechanisms are introduced to cope with the inherent unreliability of the wireless communication channel. The paper also briefly presents some basic measurements on packet transfer rates over a wireless IEEE 802.11 communication link.