This paper presents a model for building context-based systems in pervasive computing environments from high level specifications. A pervasive computing environment is viewed as a collaboration space consisting of mobile users, system services, and sensors and resources embedded in the physical environment. The approach presented here is developed for building collaborative activities in which users and environment services cooperate towards some shared objectives and tasks. The specification model allows expression of policies related to context-based discovery and secure access of resources, and role-based interactions among users and environmental services. Using several examples we illustrate the capabilities of our specification model for expressing various kinds of context-based requirements for resource access and user interactions.
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We have presented here an approach for constructing collaborative activities in pervasive computing environments using high level specifications. This work extends our previous work on a specification model for distributed collaboration systems  and development of a middleware to realize such systems  . The primary contribution of this paper is a specification model for collaborative activities that are immersed in pervasive computing environments. The model is developed to express context-based requirements for resource discovery, dynamic policies for secure resource access, and coordination among users and services in the environment. Using a set of examples, we have shown here the expressiveness of this model for specifying various kinds of context-based resource requirements and security policies. Anand Tripathi received his M.S. and Ph.D. degrees in electrical engineering from the University of Texas at Austin, in 1978 and 1980, and B.Tech in electrical engineering from the Indian Institute of Technology, Bombay, in 1972. His research interests are in distributed systems, middleware architectures, collaboration systems, pervasive computing, system security, and fault-tolerant computing. He is a professor of computer science at the University of Minnesota, Minneapolis. He worked as a Scientific Officer at Bhabha Atomic Research Center, India, during 1973–1975. During 1981–1984 he worked as a Senior Principal Research Scientist at Honeywell Computer Science Center, Minneapolis. He joined the University of Minnesota in 1984. During 1995–1997, he served as a Program Director in the Division of Computer and Communications Research at the National Science Foundation, Arlington, Virginia. Prof. Tripathi is a member of IEEE Computer Society and ACM. Currently, he is serving as an at-large member of the IEEE Computer Society Publications Board (2001–2005), and member of the editorial boards of IEEE Transactions on Computers, IEEE Pervasive Computing, and IEEE Distributed Systems Online. He served as a Program Vice Chair for International Conference on Distributed Computing Systems (in 1997). He was the Program Chair for the IEEE Symposium on Reliable Distributed Systems in 2001. He served as the Program Chair for the Second IEEE International Conference on Pervasive Computing and Communications (PerCom) 2004, and a Vice Chair for this conference in 2003. He served as the Program Chair for the IEEE Workshop on Mobile Distributed Computing (MDC) held in June 2003. He was one of the organizers of two ECOOP (European Conference on Object Oriented Programming) Workshops on exception handling (2000 and 2003), and co-editor for a Springer LNCS volume on exception handling, published in 2002. Devdatta Kulkarni is a Ph.D. student in the Department of Computer Science & Engineering at the University of Minnesota, Twin Cities. He received M.S. in Computer Science from the University of Minnesota, Duluth, in 2002. His research interests are in distributed systems, pervasive computing, and sensor networks. Tanvir Ahmed received Ph.D. degree in computer science from the University of Minnesota, Twin Cities in 2004. His dissertation addresses the research area of security in CSCW systems. He has worked and published papers on research areas, such as, policy specification and verification, middleware for collaboration systems, mobile agents, network monitoring, autonomic computing, and security in pervasive computing. He has received the M.S. degree in computer science from the University of Minnesota in 1999, and the B.S. degree in computer science from the University of Mississippi in 1995.