MediateSpace: decentralised contextual mediation using tuple spaces

Abstract

With almost four billion sensor-equipped mobile devices on the planet, the way is open for a variety of new context-based applications and services. However, this new opportunity creates concerns over privacy and access control and necessitates a robust and scalable solution. We propose the MediateSpace middleware which is a decentralised tuple space with contextual mediation capabilities for both data distributors and consumers. Distributors may restrict access by requiring the satisfaction of a contextual condition and consumers may restrict which data enters their computer (tuple conditions). Distributed X-Trees (a development of R-Trees) are used to achieve decentralisation. The system also provides Restricted Context Sharing, Triggers (performing actions upon matching certain conditions or data patterns), Module Handlers (simplifying the processing of received messages), Context Scripting (allowing the dynamic addition, removal or augmentation of structures such as triggers) and State Management (allowing state to be read and stored semi-persistently). MediateSpace could be used to support a myriad of possible applications such as context dependent data collection, collaborative tools for geographically co-located individuals and context-aware file-sharing.