Using Query Mediators for Distributed Searching in Federated Digital Libraries

摘要

Resource discovery in a distributed digital library poses many challenges, one of which is how to choose search engines for query distribution. In this paper, we describe a federated, distributed digital library architecture and introduce the notion of a query mediator as a digital library service responsible for selecting among available search engines, routing queries to those search engines, and aggregating results. We examine operational data from the NCSTRL digital library, focusing on two characteristics of distributed resource discovery: availability (will a search engine respond within a time limit) and response time (how quickly will a search engine respond, given that it does respond) and distinguishing between the query mediatory view of these characteristics and the indexer view. We also examine the accuracy of predictions we made of QM-view availability and response times of search engines.