“…"Networked virtual supercomputers, or metacomputers, are execution environments in which high-speed networks are used to connect supercomputers, databases, scientific instruments, and advanced display devices, perhaps located at geographically distributed sites" [8] 2,3 * "The National Computational Science Alliance calls its prototype infrastructure the National Technology Grid, a name derived from the notion of the electrical power grid that transformed the U.S., and indeed the world, during the past century" [22] "Computational grids are large-scale high-performance distributed computing environments that provide dependable, consistent, and pervasive access to high-end computational resources" [9] 1,8,9,10 "A computational grid is a hardware and software infrastructure that provides dependable, consistent, pervasive, and inexpensive access to high-end computational capabilities" [6] 8,9,10 "The real and specific problem that underlies the Grid concept is coordinated resource sharing and problem solving in dynamic, multiinstitutional virtual organizations" [11] 4,6,10 "A distributed network computing (NC) system is a virtual computer formed by a networked set of heterogeneous machines that agree to share their local resources with each other. A Grid is a very large scale, generalized distributed NC system that can scale to Internet-size environments with machines distributed across multiple organizations and administrative domains" [18] 1,2 * ,3,4,5,7 * "Grid technologies and infrastructure support the sharing and coordinated use of diverse resources in dynamic, distributed virtual organizations -that is, the creation, from geographically distributed components operated by distinct organizations with differing policies, of virtual computing systems that are sufficiently integrated to deliver the desired QoS" [12] 2,3,4,5,6,7 * ,8,10…”