A Peer-to-Peer Approach to Resource Discovery in Grid Environments

Computational grids provide mechanisms for sharing and accessing large and heterogeneous collections of remote resources such as computers, online instruments, storage space, data, and applications. Resources are requested (”discovered”) by specifying a set of desired attributes. Resource attributes have various degrees of dynamism, from mostly static attributes, such as operating system version, to highly dynamic ones, such as available network bandwidth or CPU load. Another dimension of dynamism is introduced by variable and highly diverse sharing policies: resources are made available to the grid community based on locally defined and potentially changing policies. In such a dynamic environment it is often more efficient to forward requests than to disseminate resource information that soon becomes stale. We investigate a set of request forwarding strategies in a peer-to-peer like architecture: each peer acts independently, based on possibly partial or outdated information about the rest of the system and forwards the requests it cannot solve to another peer. We investigate these strategies in environments with different sharing characteristics, different request distributions, and on networks of up to 32768 (215) peers. The results allow to characterize the correlation between resource discovery performance based on request forwarding, resource sharing characteristics, and user request patterns.