Within a digital library, collections may range from an ad hoc set of objects that serve a temporary purpose to established library collections intended to persist through time. The objects in these collections vary widely, from library and data center holdings to pointers to real‐world objects, such as geographic places, and the various metadata schemas that describe them. The key to integrated use of such a variety of collections in a digital library is collection metadata that represents the inherent and contextual characteristics of a collection. The Alexandria Digital Library (ADL) Project has designed and implemented collection metadata for several purposes: in XML form, the collection metadata “registers” the collection with the user interface client; in HTML form, it is used for user documentation; eventually, it will be used to describe the collection to network search agents; and it is used for internal collection management, including mapping the object metadata attributes to the common search parameters of the system.

The Alexandria Digital Library (ADL) is one of the six digital library projects funded by NSF, DARPA, and NASA. ADL's collection and services focus on information containing georeferences: maps, images, data sets, text, and other information sources with links to geographic locations. During this study period, three different user interfaces were developed and tested by user groups. User feedback was collected through various formal and informal approaches and the results fed back into the design and implementation cycle. This article describes the evolution of the ADL system and the effect of user evaluation on that evolution. ADL is an ongoing project; user feedback and evaluation plans for the remainder of the project are described.

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The Alexandria Digital Library (ADL) is one of the six digital library projects funded by NSF, DARPA, and NASA. ADL's collection and services focus on information containing georeferences: maps, images, data sets, text, and other information sources with links to geographic locations. During this study period, three different user interfaces were developed and tested by user groups. User feedback was collected through various formal and informal approaches and the results fed back into the design and implementation cycle. This article describes the evolution of the ADL system and the effect of user evaluation on that evolution. ADL is an ongoing project; user feedback and evaluation plans for the remainder of the project are described.

Information retrieval o ver the Internet increasingly requires the ltering of thousands of i n f o r mation sources. As the number and variety of sources increases, new ways of automatically summarizing, discovering, and selecting sources relevant t o a u s er's query a re needed. Pharos i s a h i g hly scalable distributed architecture for locating heterogeneous information sources. Its design is hierarchical, thus allowing it to scale well as the numberofinformation sources increases. We demonstrate the feasibility of the Pharos architecture using 2500 Usenet newsgroups as separate collections. Each n e wsgroup is summarized viaautomated Library o f C o ngress classi cation. We s how that using Pharos as an i n termediate retrieval mechanism provides acceptable accuracy of source selection compared to selecting sources using complete classi cation information, while maintaining good scalability. This implies that hierarchical distributed metadata and automated classi cation are potentially useful paradigms to address scalability problems in large-scale distributed information r etrieval applications.