A Survey of Digital Library Aggregation Services

This report provides an overview of a diverse set of more than thirty digital library aggregation services, organizes them into functional clusters, and then evaluates them more fully from the perspective of an informed user. Most of the services under review rely wholly or partially on the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH), although some of them predate its inception and a few use predominantly Z39.50 protocols. In the opening section of this report, each service is annotated with its organizational affiliation, subject coverage, function, audience, status, and size. Critical issues surrounding each of these elements are presented in order to provide the reader with an appreciation of the nuances inherent in seemingly straightforward factual information, such as audience or size. Each service is then grouped into one of five functional clusters: • open access e-print archives and servers; • cross-archive search services and aggregators; • from digital collections to digital library environments; • from peer-reviewed referratories to portal services; • specialized search engines

Overview of Digital Library Components and Developments

Digital libraries are being built upon a firm foundation of prior work as the high-end information systems of the future. A component architecture approach is becoming popular, with well established support for key components like the repository, especially through the Open Archives Initiative. We consider digital objects, metadata, harvesting, indexing, searching, browsing, rights management, linking, and powerful interfaces. Flexible interaction will be possible through a variety of architectures, using buses, agents, and other technologies. The field as a whole is undergoing rapid growth, supported by advances in storage, processing, networking, algorithms, and interaction. There are many initiatives and developments, including those supporting education, and these will certainly be of benefit in Latin America

Lightweight Federation of Non-Cooperating Digital Libraries

This dissertation studies the challenges and issues faced in federating heterogeneous digital libraries (DLs). The objective of this research is to demonstrate the feasibility of interoperability among non-cooperating DLs by presenting a lightweight, data driven approach, or Data Centered Interoperability (DCI). We build a Lightweight Federated Digital Library (LFDL) system to provide federated search service for existing digital libraries with no prior coordination. We describe the motivation, architecture, design and implementation of the LFDL. We develop, deploy, and evaluate key services of the federation. The major difference to existing DL interoperability approaches is one where we do not insist on cooperation among DLs, that is, they do not have to change anything in their system or processes. The underlying approach is to have a dynamic federation where digital libraries can be added (removed) to the federation in real-time. This is made possible by describing the behavior of participating DLs in an XML-based language that the federation engine understands. The major contributions of this work are: (1) This dissertation addresses the interoperability issues among non-cooperating DLs and presents a practical and efficient approach toward providing federated search service for those DLs. The DL itself remains autonomous and does not need to change its structure, data format, protocol and other internal features when it is added to the federation. (2) The implementation of the LFDL is based on a lightweight, dynamic, data-centered and rule-driven architecture. To add a DL to the federation, all that is needed is observing a DL\u27s interaction with the user and storing the interaction specification in a human-readable and highly maintainable format. The federation engine provides the federated service based on the specification of a DL. A registration service allows dynamic DL registration, removal, or modification. No code needs to be rewritten or recompiled to add or change a DL. These notions are achieved by designing a new specification language in XML format and a powerful processing engine that enforces and implements the rules specified using the language. (3) In this thesis we explore an alternate approach where searches are distributed to participating DLs in real time. We have addressed the performance and reliability problems associated with other distributed search approaches. This is achieved by a locally maintained metadata repository extracted from DLs, as well as an efficient caching system based on the repository

Semantic and pragmatic characterization of learning objects

Tese de doutoramento. Engenharia Informática. Universidade do Porto. Faculdade de Engenharia. 201

Volume 31 - 2000: ELECTRONIC INFORMATION SUMMIT: NEW DEVELOPMENTS AND THEIR IMPACTS - Proceedings of the 35th Meeting of the Geoscience Information Society

Proceedings of the 35th Meeting of the Geoscience Information Society held November 11-15, 2000 in Reno, Nevad

The Theory and Practice of Online Learning

Every chapter in the widely distributed first edition has been updated, and four new chapters on current issues such as connectivism and social software innovations have been added. Essays by practitioners and scholars active in the complex, diverse, and rapidly evolving field of distance education blend scholarship and research; practical attention to the details of teaching and learning; and mindful attention to the economics of the business of education