Discover: A Resource Discovery System Based on Content Routing

We have built an HTTP based resource discovery system called Discover that provides a single point of access to over 500 WAIS servers. Discover provides two key services: query re nement and query routing. Query re nement helps a user improve a query fragment to describe the user's interests more precisely. Once a query has been re ned and describes a manageable result set, query routing automatically forwards the query to the WAIS servers that contain relevant documents. Abbreviated descriptions of WAIS sites called content labels are used by the query re nement and query routing algorithms. Our experimental results suggest that query re nement in conjunction with the query routing provides an e ective way to discover resources in a large universe of documents. Our experience with query re nement has convinced us that the expansion of query fragments is essential for using a large, dynamically changing, heterogenous distributed information system.