Designing Mediation for Context Aware Applications

Many context-aware services make the assumption that the context they use is completely accurate. However, in reality, both sensed and interpreted context is often ambiguous. A challenge facing the development of realistic and deployable context-aware services, therefore, is the ability to handle ambiguous context. Although some of this ambiguity may be resolved using automatic techniques, we argue that correct handling of ambiguous context will often need to involve the user. We use the term mediation to refer to the dialogue that ensues between the user and the system. In this paper, we describe an architecture that supports the building of context-aware services that assume context is ambiguous and allows for mediation of ambiguity by mobile users in aware environments. We discuss design guidelines that arise from supporting mediation over space and time, issues not present in the graphical user interface domain, where mediation has typically been used in the past. We illustrate the use of our architecture and the design guidelines and evaluate it through three example context-aware services, a word predictor system, an In/Out Board, and a reminder tool.