Using Query Mediators for Distributed Searching in Federated Digital Libraries

TL;DR

This paper proposes a query mediator architecture for distributed searching in federated digital libraries, analyzing its operational characteristics and how it manages search engine selection, query routing, and result aggregation.

Contribution

It introduces the concept of a query mediator service and investigates its operational effectiveness in federated digital library environments.

Findings

Distributed resource discovery has variable availability and response times.

Query mediators differ in their view of indexer performance compared to indexers themselves.

Operational data reveals key characteristics affecting search efficiency.

Abstract

We describe an architecture and investigate the characteristics of distributed searching in federated digital libraries. We 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 distributed digital library that reveals a number of characteristics of distributed resource discovery. These include availability and response time of indexers and the distinction between the query mediator view of these characteristics and the indexer view.