Computational Scientists often cannot easily access the large amounts of resources their applications require. Legion is a collection of software services that facilitate the secure and easy use of local and non-local resources by providing
the illusion of a single virtual machine from heterogeneous, geographically-distributed resources. This paper describes the
newest additions to Legion that enable high-performance (capacity) computing as well as secure, fault-tolerant and collaborative
(capability) computing.
This work was supported in part by the National Science Foundation grant EIA- 9974968, DoD/Logicon contract 979103 (DAHC94-96-C-0008),
and by the NASA Information Power Grid program.