Design of An Open and Secure Ubiquitous Computing System

Many difficulties such as scalability and security problems are addressed in this paper, and some concluded principles are given to guide the design and implementation of a large-scale open and secure ubiquitous computing system.A service toolkit (aCAST) consisting of a set of software components and detector services have been developed, and a Context Aware Call Forwarding system has also been developed as a proof-of-concept test bed using aCAST. The off-the-shelf devices, such as Bluetooth mobile phones and PDAs, is used as user devices and the Session Initiation Protocol (SIP) is adopted as an open communication protocol.