Gross, TomOemig, ChristophStary, Christian2017-11-222017-11-2220053-486-57805-7https://dl.gi.de/handle/20.500.12116/6973Instant messaging systems facilitate the coordination of geographically distributed users through support for presence and availability information, and ad-hoc conversations among online users. However, despite their widespread use they seem to be designed and developed from a technology-push, rather than a user-centred design perspective. In fact, concerning the subtleties of human behaviour and human perception of others there is a broad gap between the body of knowledge in sociology, and the functionality of these systems. In this paper we present concepts for the support of advanced and nuanced online states; for the automatic and precise inference of the online states based on data from software sensors and hardware sensors; and the adaptation of the system behaviour to the inferred online state. Furthermore, we describe the implementation of these concepts on top of two open platforms for the rapid and easy development of sensor-based, and instant messaging infrastructures.enText/Conference Paper