Pervasive computing, with its focus on users and their tasks rather than on computing devices and technology, provides an attractive vision for the future of computing. But, while hardware and networking infrastructure to realize this vision are increasingly becoming a reality, precious few applications run in this infrastructure. We believe that this lack of applications can be attributed to three characteristics that are inadequately addressed by existing systems. First, devices are

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... ous, ranging from wearable devices to conventional computers. Second, network connectivity often is limited and intermittent. And, third, interactions typically involve several autonomous administrative domains. In this paper, we introduce a system architecture that directly addresses these challenges. Our architecture is targeted at application developers and administrators, and it supports mobile computations, persistent storage, and resource discovery within a single, comprehensive framework.