Improving the performance, availability, and security of data access for opportunistic mobile computing

Abstract

An opportunistic model of mobile computing is presently emerging in which users can fully benefit from their personal computing environment wherever they are without having to carry heavy-weight mobile systems with them. The transition to this model can be seen as part of the pervasive computing vision, being catalyzed by the near ubiquity of powerful smart phones, the increasing availability of local PC hardware, and recent trends in virtualization and cloud computing. The fate of the opportunistic mobile computing model will be essentially decided by the performance, availability, and security of data access relative to alternative solutions. Mobile users require safe and efficient access to their data from whatever PC or device they are currently using, wherever they may be. These requirements expose several new challenges to the performance, availability, and security of user data access under opportunistic mobile computing conditions. In this dissertation, we identify challenges to user data access within the opportunistic mobile computing model, present novel approaches to address them, and demonstrate the effectiveness of these approaches through extensive experimentation. To improve the performance of data access for opportunistic mobile computing, we introduce the concept of safe borrowing of local storage, which we prototyped as the TransPart system. To improve the availability of data access for opportunistic mobile computing, we introduce the concept of a self-cleaning portable cache, which we prototyped as the Horatio system. To improve the security of remote data access for opportunistic mobile computing, we introduce the Working Set-Based Access Control (WSBAC) scheme, which applies the concept of the working set to distributed file system access control. The main conclusion of our research is that opportunistic mobile computing can be realized in a safe and efficient manner for mobile users. Given the ad-hoc nature of opportunistic mobile computing, it is likely that the challenges identified in this dissertation will continue to exist into the foreseeable future. Fortunately, as our research shows, they can be addressed using nascent technologies and applying our concepts without violating the basic tenet of opportunistic mobile computing, namely to minimize the burden of what hardware users must carry.