DATE: Thursday , January 23, 2003
TIME: Noon - 1 pm
PLACE: Wean Hall 8220

Armando Fox
Assistant Professor, Stanford University

Portability, Extensibility and Robustness in Ubiquitous Computing System

The dynamism and heterogeneity in ubicomp environments on both short and long time scales implies that middleware platforms for these environments need to be designed ground up for portability, extensibility and robustness. We describe how we met these requirements in iROS, a middleware platform for a class of ubicomp environments, through the use of three guiding principles: economy of mechanism, client simplicity and levels of indirection. Apart from design arguments and experimental results, experience through several deployments with a variety of apps, in most cases not done by the original designers of the system, provides some validation in practice that the design decisions have in fact resulted in the intended portability, extensibility and robustness. A retrospective examination of the system leads us to the following lesson: A logically-centralized design and physically-centralized implementation enables the best behavior in
terms of extensibility and portability along with ease of administration, and sufficient behavior in terms of scalability and robustness. We discuss this lesson and its implications for ongoing and future work on iROS.

Armando Fox joined the Stanford faculty as an Assistant Professor in January 1999, after getting his Ph.D. from UC Berkeley as a researcher in the Daedalus wireless and mobile computing project. His primary
research interests are systems approaches to improving dependability (the Recovery-Oriented Computing project) and system software support for ubiquitous computing (the Interactive Workspaces project). In
previous lives, Armando received a BSEE from M.I.T. and an MSEE from the University of Illinois, and worked as a CPU architect at Intel Corp. He is also an ACM member and a founder of ProxiNet, Inc. (now a division of PumaTech), which commercialized thin client mobile computing technology he helped develop at UC Berkeley. He can be reached at

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