Pharos

Abstract

Pharos is a .sca&zble distributed architecture for locating heterogeneous informatdon sources. !7he system incorporates a hierarcfiical metaduta structure into a multi-level rettieval system. Queries are resolved through an iterative decisionmaking process. The first step retrieves coarse-grain metadata, about all sources, stored on iocal, mastively replicated, high-level servers. Further steps retrieve more detailed matadata, about a greatly reduced set of souwes, stored on remote, sparsety replicated, topic-based mid-level servers. We present results of a simulation which indicate the feasibility of the architecture. We describe the structure, distribution, and retrieval of the metadata in Pharos to enable users to locate desirable information soumes over the Internet.