Sensing and Making Sense : Designing Middleware for Context Aware Computing

Abstract: Computing devices are becoming wireless, smaller and embedded into other artifacts. Some of them are mobile while others are built into the environment. The novel technologies are also becoming more dependent of communication with other computing devices over different kinds of networks. These interconnected devices constitute locally and globally distributed service environments that will enforce new requirements on the design of software systems. These new type of environments provide both opportunities for new types of applications as well as a number of new problems that will have to be addressed. One approach that have been suggested both in order to provide new functionalities and as a possible solution to some of the problems is to try and collect and incorporate aspects of the /context/ of a person, activity or device as a part of the computer system. This thesis addresses some issues that have to be considered when designing this kind of systems. In particular the thesis examines how to design middleware that can support the creation of context aware applications. As a part of this work several instances of such systems have been implemented and put in use and tested in various applications. Some key problems with respect to the design of context information middleware are also identified and examined. One question that is addressed concerns the clash between the need for internal representations of context information and the goal of middleware to support a broad range of applications. Another problem that has been addressed concerns how to create means for context aware service discovery in ubiquitous computing environments. Various mechanisms that address these problems have been implemented and tested. Finally the work addresses issues related to the role of the users in this kind of systems. Implementations and experiments have been performed where users take more active roles in aspects of system maintenance and adaptation as well as in the interpretation and representation of context information.