Legion -- a view from 50,000 feet

The coming of giga-bit networks makes possible the realization of a single nationwide virtual computer com-prised of a variety of geographically distributed high-pe6ormance machines and workstations. To realize the potential that the physical infrastructure provides, soft-ware must be developed that is easy to use, supports large degrees of parallelism in applications code, and manages the complexity of the underlying physical sys-tem for the usel: Legion is a metasystem project at the University of Virginia designed to provide users with a transparent intelface to the available resources, both at the programming interface level as well as at the user level. Legion addresses issues such as parallelism, fault-tolerance, security, autonomy, heterogeneity, resource management, and access transparency in a multi-language environment. In this paper we present a high-level overview of Legion, its vision, objectives, a brief sketch of how some of those objectives will be met, and the current status of the project.2 1 The Opportunity The dramatic increase in ubiquitously available net-work bandwidth will qualitatively change how the world computes, communicates, and collaborates. The rapid expansion of the world-wide web, and the changes that it has wrought are just the beginning. As high band-width connections become available they “shrink ” dis-tance and change our modes of computation, storage and interaction. Inevitably, users will operate in a wide-area environment that transparently consists of worksta-tions, personal computers, graphics rendering engines, supercomputers, and non-traditional devices: e.g., TVs