Legion-a view from 50,000 feet

The coming of giga-bit networks makes possible the realization of a single nationwide virtual computer comprised of a variety of geographically distributed high-performance machines and workstations. To realize the potential that the physical infrastructure provides, software must be developed that is easy to use, supports a large degree of parallelism in the application code, and manages the complexity of the underlying physical system for the user. Legion is a metasystem project at the University of Virginia designed to provide users with a transparent interface 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.