Presence Service in Mobile Environment
                          Marko Saaresto
          Helsinki Institute for Information Technology
                   marko.saaresto@hiit.fi


Introducing rich presence services in a mobile environment faces many 
challenges. The observation and collection of presence information 
from multiple changing source must be managed, and the information 
processed in to an understandable context. The more pervasive and 
sensitive the observed information is, the more alert and fine-grained 
must be the guarding of a persons privacy. Also, a presence service 
must be both tolerant of and adaptive to different connectivity 
situations. Yet the presence-aware applications should neither be
difficult to implement nor require excessive attention from the 
end-user.

The presence service prototype being implemented is a base for testing 
different techniques for addressing the above issues. Its architecture 
rests on the Fuego Core notification service, taking advantage of the 
network mobility and adaptivity features. The presence service 
provides facilities for data collection, access control and selective 
state change notifications. It can be embedded in collaboration tools 
to enhance group-awareness, or as a way of providing presence 
information for communication tools like instant messengers.

The prototype enables experimentation with proactive context 
recognition, data mining on presence information and dynamic service 
reconfiguration. Different privacy enhancements like data blinding, 
decentralized control and proactive access control can also be 
experimented with. Another field of interest is the use of user 
profiles and presence information in supporting both ad-hoc and 
opportunistic communication.