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Tienari H (2002)
Modular and intelligent architecture for context-aware telephony services.
M.Sc. thesis, Department of Electrical Engineering, University of Oulu, Finland (in Finnish).

Context-aware services perceive everyday circumstances of users, for example their location. Context can be utilised among other things in interpersonal communications in the form of smart context-aware communication services. For example if a cellular phone rings during a symphony concert or in an important meeting, it is generally considered as improper behaviour in our culture. If a communication device automatically notices its user's context, it can adapt accordingly and an awkward situation can be avoided. Communications become more effective as the number of unsuccessful contact attempts decreases. In addition to location information, the utilised context can be for example knowledge of a user's current social situation or his/her physiological state. In practice context information is gathered by different sensors that may reside in the user's terminal or in the environment. Typically the components that perceive the physical world are not part of a certain service application and thus not under its control. The system by its basic nature is distributed to the network. Often components are independently mobile, behind slow wireless connections, and sometimes some of them are unavailable due to network breakdowns or other failures. This all places certain technical distribution challenges to the system. There is no sense in that every service in use would require its own sensors and context delivery mechanism. To optimise the use of a sensor and information delivery resources, and to ease the development of services, it is a necessity that services share common context sensing and delivery infrastructure. In this thesis, some existing architectural solutions are evaluated, and then a new experimental system is developed as an environment in which we try to enhance their weaknesses. Especially we try to ease the development of new services by moving responsibility of context handling from services to the context server, by offering context handling user interfaces for the service applications as a mobile code, and generally aiming at as modular an architecture as possible. The architecture and the platform are tested in practice by building a simple context-aware message interchange service. The gained findings are very encouraging.