Eric Lemar's research while affiliated with University of Washington Seattle and other places

Pervasive computing provides an attractive vision for the future of computing. Computational power will be available everywhere. Mobile and stationary devices will dynamically connect and coordinate to seamlessly help people in accomplishing their tasks. For this vision to become a reality, developers must build applications that constantly adapt to a highly dynamic computing environment. To make the developers' task feasible, we present a system architecture for pervasive computing, called one.world . Our architecture provides an integrated and comprehensive framework for building pervasive applications. It includes services, such as discovery and migration, that help to build applications and directly simplify the task of coping with constant change. We describe our architecture and its programming model and reflect on our own and others' experiences with using it.

Many interesting pervasive applications require the maintenance of state, but few pervasive computing systems provide a compelling system for managing such state. Although conventional storage abstractions can fill some of these needs, the unique character of the pervasive environment suggests slightly di#erent answers. Pervasive applications often have to work with data in forms they were not directly coded to support, need to be able to extend the behavior of existing applications, and must support mobility across a wide range of devices. The one.world storage architecture supports the needs of pervasive computing and overcomes many of these limitations in other systems. This paper examines the design decisions made in the one.world storage architecture and API and provides an initial look at the lessons learned from the implementation of this design.

this paper, we explore how to build applications for pervasive computing environments. Pervasive, or ubiquitous, computing [Weiser 1991] has the potential to radically transform the way people interact with computers. The key idea behind pervasive computing is to deploy a wide variety of computing devices throughout our living and working spaces. These devices coordinate with each other and network services [Dertouzos 1999], with the goal of providing people with universal Authors' addresses: Robert Grimm, Department of Computer Science, New York University, 715 Broadway, Room 711, New York, NY, 10003. Janet Davis, Eric Lemar, Adam MacBeth, Steven Swanson, Tom Anderson, Brian Bershad, Gaetano Borriello, Steven Gribble, David Wetherall, Department of Computer Science and Engineering, University of Washington, Box 352350, Seattle, WA 98195

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 becoming a reality, precious few applications run in this infrastructure. We believe that this lack of applications stems largely from the fact that it is currently too hard to design, build, and deploy applications in the pervasive computing space.

be able to work properly in constantly changing situations. Functions that interact with users and infrastructure must be maintained at tolerable levels even if devices and users are roaming, users switch devices or engage new ones, and the network provides only limited services. In this position paper, we present an approach based on exposing programmers to change while providing them with tools that make dealing with highly dynamic systems much more straightforward. We are developing several applications using our infrastructure and have already released to the research community a version of our system, called one.world . Our next step is to build a user community and to this end we are preparing to offer a workshop to interested colleagues in the fall of 2001 where they will be able to prototype their own applications and leave with working code.

Pervasive computing provides an attractive vision for the future of computing. Computational power will be available everywhere. Mobile and stationary devices will dynamically connect and coordinate to seamlessly help users in accomplishing their tasks. However, for this vision to become a reality, developers must build applications that constantly adapt to a highly dynamic computing environment. To make the developers' task feasible, we introduce a system architecture for pervasive computing, called one.world . Our architecture provides an integrated and comprehensive framework for building pervasive applications. It includes a set of services, such as service discovery, checkpointing, migration, and replication, that help to structure applications and directly simplify the task of coping with constant change. We describe the design and implementation of our architecture and present the results of an evaluation, which includes two case studies.

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 becoming a reality, precious few applications run in this infrastructure. We believe that this lack of applications stems largely from the fact that it is currently too hard to design, build, and deploy applications in the pervasive computing space. In this paper, we argue that existing approaches to distributed computing are flawed along three axes when applied to pervasive computing; we sketch out alternatives that are better suited for this space. First, application data and functionality need to be kept separate, so that they can evolve gracefully, in a global computing infrastructure. Second, applications need to be able to acquire any resource they need at any time, so that they can continuously provide their services in a highly dynamic environment. Third, pervasive computing requires a common system platform, allowing applications to be run across the range of devices and to be automatically distributed and installed.

... be able to work properly in constantly changing situations. Functions that interact with users and infrastructure must be maintained at tolerable levels even if devices and users are roaming, users switch devices or engage new ones, and the network provides only limited services. In this position paper, we present an approach based on exposing programmers to change while providing them with tools that make dealing with highly dynamic systems much more straightforward. We are developing several applications using our infrastructure and have already released to the research community a version of our system, called one.world . Our next step is to build a user community and to this end we are preparing to offer a workshop to interested colleagues in the fall of 2001 where they will be able to prototype their own applications and leave with working code.

This paper explores migration, the ability to move an application between devices, in the context of pervasive, or ubiquitous, computing. Pervasive computing, with its vision of information access anytime and anywhere, introduces a new class of applications that seamlessly follow people as they move through the physical world. As a result, mi-gration becomes an important building block for the development and deployment of pervasive applica-tions. However, the main challenge with migration is to strike a reasonable balance between the com-plexity of implementing migration and the actual utility delivered to applications. In this paper, we introduce a migration service for pervasive applica-tions that marks a new, practical design point in the design space. We explain the trade-offs made in its design, detail its implementation, and reflect on our own and others' experiences with using it.