The goal of the Alexandria Digital Library (ADL) is to provide online access to distributed collections of geographically-referenced information. The ADL will comprise a set of Internet nodes implementing various combinations of collections, catalogs, interfaces, and ingest facilities (the four primary components of the ADL architecture.) ADL development efforts to date have concentrated on the catalog and user interface components. The first ADL development cycle yielded a stand-alone rapid prototype (RP) system, based on commercial database management (DBMS) and geographic information system (GIS) technology. The second (current) development cycle is assembling a ``Web prototype'' (WP) spatial data library accessible from the World Wide Web (WWW). In addition to the metadata issues associated with the catalog, and the functionality issues associated with a complex WWW interface, the WP includes preliminary applications of image processing and parallel computing technologies.
The Alexandria Digital Library (ADL) is an online information system that is based on a traditional map library housed in the Map and Imagery Laboratory (MIL) in the Davidson Library at UCSB. The ADL is being implemented as part of the [Alexandria] Project's testbed environment. This remainder of this paper describes the ADL Testbed at a variety of levels. We begin with a brief description of the physical components of the Testbed, followed by a description of the logical system architectures that the Testbed is intended to support, followed by a detailed discussion of the physical architecture of the two digital library systems the Testbed has supported to date.