The use of input devices adopted from desktop computing is not feasible for interacting with complex services surrounding the user in highly computerised environments. Powerful mobile computers and high speed wireless networking enable enhanced interaction in a world of ambient services, e.g. by employing a mobile phone, using gestures, or observing body movements. The arising heterogeneity of hardware, software and communication technology combined with an open set of interaction styles narrow the compatibility of the user interface and the service to control. A common understanding of a...