Carl Lagoze

The open archives initiative: building a low-barrier interoperability framework

The Open Archives Initiative (OAI) develops and promotes interoperabil ity solutions that aim to facilitate the efficient dissemination of content. The roots of the OAI lie in the E-Print community. Over the last year its focus has been extended to include all content providers. This paper describes the recent history of the OAI - its origins in promoting E-Prints, the broadening of its focus, the details of its technical standard for metadata harvesting, the applications of this standard, and future plans.

Fedora: an architecture for complex objects and their relationships

The Fedora architecture is an extensible framework for the storage, management, and dissemination of complex objects and the relationships among them. Fedora accommodates the aggregation of local and distributed content into digital objects and the association of services with objects. This allows an object to have several accessible representations, some of them dynamically produced. The architecture includes a generic Resource Description Framework (RDF)-based relationship model that represents relationships among objects and their components. Queries against these relationships are supported by an RDF triple store. The architecture is implemented as a web service, with all aspects of the complex object architecture and related management functions exposed through REST and SOAP interfaces. The implementation is available as open-source software, providing the foundation for a variety of end-user applications for digital libraries, archives, institutional repositories, and learning object systems.

Flexible and Extensible Digital Object and Repository Architecture (FEDORA)

We describe a digital object and respository architecture for storing and disseminating digital library content. The key features of the architecture are: (1) support for heterogeneous data types; (2) accommodation of new types as they emerge; (3) aggregation of mixed, possibly distributed, data into complex objects; (4) the ability to specify multiple content disseminations of these objects; and (5) the ability to associate rights management schemes with these disseminations. This architecture is being implemented in the context of a broader research project to develop next-generation service modules for a layered digital library architecture.

Dienst: an architecture for distributed document libraries

As one of the five universities participating in the ARPA-sponsored Computer Science Technical Report project, we at Cornell have developed a digital library architecture called Dienst. Dienst is a protocol and implementation that provides Internet access to a distributed, decentralized multi-format document collection. The collection is managed by a set of interoperating Dienst servers distributed over the Internet. These servers provide three digital library services: repositories of multi-format documents; indexes into the document collection and search engines for these indexes; and user interfaces for browsing, searching, and accessing the collection.

NCSTRL: design and deployment of a globally distributed digital library

The World Wide Web provides unprecedented access to globally distributed content. The extent and uniform accessibility of the Web has proven beneficial for research, education, commerce, entertainment, and numerous other uses. Ironically, the fact that the Web is an information space without boundaries has also proven its biggest flaw. Key aspects of libraries, such as selectivity of content, customization of tools and services relative to collection and patron characteristics, and management of content and services are noticeably absent. Over the past four years, we researched the technology and deployment of a digital library architecture that makes it possible to create managed information spaces, digital libraries, within the World Wide Web. Our work has taken place in the context of NCSTRL,1a digital library of computer science research reports. The technical foundation of NCSTRL is Dienst, a protocol and architecture for distributed digital libraries that we developed as part of the DARPA‐funded Computer Science Technical Reports Project. At the time of the writing of this paper, the NCSTRL collection consisted of papers from more than 100 research institutions residing in servers distributed across the United States, Europe, and Asia. In addition, the Dienst protocol and implementation has been successfully adopted by a number of other distributed collections. In this paper, we review our experiences with NCSTRL and Dienst, describe some of the lessons we have learned from the deployment experience, and define some directions for the future.

A New Approach to Analyzing Patterns of Collaboration in Co-authorship Networks - Mesoscopic Analysis and Interpretation

This paper focuses on methods to study patterns of collaboration in co-authorship networks at the mesoscopic level. We combine qualitative methods (participant interviews) with quantitative methods (network analysis) and demonstrate the application and value of our approach in a case study comparing three research fields in chemistry. A mesoscopic level of analysis means that in addition to the basic analytic unit of the individual researcher as node in a co-author network, we base our analysis on the observed modular structure of co-author networks. We interpret the clustering of authors into groups as bibliometric footprints of the basic collective units of knowledge production in a research specialty. We find two types of coauthor-linking patterns between author clusters that we interpret as representing two different forms of cooperative behavior, transfer-type connections due to career migrations or one-off services rendered, and stronger, dedicated inter-group collaboration. Hence the generic coauthor network of a research specialty can be understood as the overlay of two distinct types of cooperative networks between groups of authors publishing in a research specialty. We show how our analytic approach exposes field specific differences in the social organization of research.

Core services in the architecture of the national science digital library (NSDL)

We describe the core components of the architecture for the National Science Digital Library (NSDL). Over time the NSDL will include heterogeneous users, content, and services. To accommodate this, a design for a technical and organization infrastructure has been formulated based on the notion of a spectrum of interoperability. This paper describes the first phase of the interoperability infrastructure including the metadata repository, search and discovery services, rights management services, and user interface portal facilities.

The Making of the Open Archives Initiative Protocol for Metadata Harvesting.

The authors, who jointly serve as the Open Archives Initiative (OAI) executive, reflect on the three‐year history of the OAI. Three years of technical work recently culminated in the release of a stable production version 2 of the OAI Protocol for Metadata Harvesting (OAI‐PMH). This technical product, the work that led up to it, and the process that made it possible have attracted some favor from the digital library and information community. The paper explores a number of factors in the history of the OAI that the authors believe have contributed to this positive response. The factors include focus on a defined problem statement, an operational model in which strong leadership is balanced with solicited participation, a healthy dose of community building and support, and sensible technical decisions.

Developing services for open eprint archives: globalisation, integration and the impact of links

The rapid growth of scholarly information resources available in electronic form and their organisation by digital libraries is proving fertile ground for the development of sophisticated new services, of which citation linking will be one indispensable example. Many new projects, partnerships and commercial agreements have been announced to build citation linking applications. This paper describes the Open Citation (OpCit) project, which will focus on linking papers held in freely accessible eprint archives such as the Los Alamos physics archives and other distributed archives, and which will build on the work of the Open Archives initiative to make the data held in such archives available to compliant services. The paper emphasises the work of the project in the context of emerging digital library information environments, explores how a range of new linking tools might be combined and identifies ways in which different linking applications might converge. Some early results of linked pages from the OpCit project are reported.

Detecting research topics via the correlation between graphs and texts

In this paper we address the problem of detecting topics in large-scale linked document collections. Recently, topic detection has become a very active area of research due to its utility for information navigation, trend analysis, and high-level description of data. We present a unique approach that uses the correlation between the distribution of a term that represents a topic and the link distribution in the citation graph where the nodes are limited to the documents containing the term. This tight coupling between term and graph analysis is distinguished from other approaches such as those that focus on language models. We develop a topic score measure for each term, using the likelihood ratio of binary hypotheses based on a probabilistic description of graph connectivity. Our approach is based on the intuition that if a term is relevant to a topic, the documents containing the term have denser connectivity than a random selection of documents. We extend our algorithm to detect a topic represented by a set of terms, using the intuition that if the co-occurrence of terms represents a new topic, the citation pattern should exhibit the synergistic effect. We test our algorithm on two electronic research literature collections,arXiv and Citeseer.Our evaluation shows that the approach is effective and reveals some novel aspects of topic detection.