Reference Linking in a Hybrid Library Environment

This is the third part of our papers about reference linking in a hybrid library environment. The first part described the state-of-the-art of reference linking and contrasted various approaches to the problem. It identified static and dynamic linking solutions, open and closed linking frameworks as well as just-in-case and just-in-time linking. The second part introduced SFX, a dynamic, just-in-time linking solution we built for our own purposes. However, we suggested that the underlying concepts were sufficiently generic to be applied in a wide range of digital libraries. In this third part we show how this has been demonstrated conclusively in the "SFX@Ghent & SFX@LANL" experiment. In this experiment, local as well as remote distributed information resources of the digital library collections of the Research Library of the Los Alamos National Laboratory and the University of Ghent Library have been used as starting points for SFX-links into other parts of the collections. The SFX-framework has further been generalized in order to achieve a technology that can easily be transferred from one digital library environment to another and that minimizes the overhead in making the distributed information services that make up those libraries interoperable with SFX. This third part starts with a presentation of the SFX problem statement in light of the recent discussions on reference linking. Next, it introduces the notion of global and local relevance of extended services as well as an architectural categorization of open linking frameworks, also referred to as frameworks that are supportive of selective resolution. Then, an in-depth description of the generalized SFX solution is given. Rephrasing the SFX problem statement The problem statement It is relevant to rephrase the SFX problem statement in the context of the meetings and the subsequent reports and publications on reference linking organized by the Digital Library Federation (DLF), the National Information Standards Organization (NISO), the National Federation of Abstracting and Indexing Services (NFAIS), and the Society for Scholarly Publishing (SSP) (Caplan 1999a; Caplan 1999b; Caplan & Arms 1999; Needleman 1999). The generic statement of the reference linking problem, as defined by the working group on reference linking was (Caplan 1999a; Caplan & Arms 1999): Given the information in a standard citation, how does one get to the thing to which it refers? However, the working group concentrated on a specific variation on this: Given the information in a citation to a journal article, how does a user get from the citation to an appropriate copy of the article? The SFX research also addresses these problems, but only as an instance of a more general problem that can be formulated as: Given bibliographic metadata, how does one present relevant extended services for it? Bibliographic metadata as a starting point Clearly, the SFX research is not only concerned about information in a standard citation. Its starting point is bibliographic metadata in general. As such, information entities originating from typical scholarly resources such as records from abstracting & indexing databases, OPAC systems and preprint archives can be used as a starting point in the SFX problem statement. This is also the case for citations to both journal articles and books found in journal articles or books. But even fractional bibliographic metadata such as an author name taken from an e-mail message is a valid starting point in the SFX problem statement. Extended services as a goal A similar generalization holds for the target of the problem statement since the SFX research is not only concerned about linking to the full-text that corresponds to a citation in a journal article. It aims at the presentation of a variety of extended services for whichever metadata is used as a starting point. Extended services are services that present an information entity in a digital library -defined as the link-source -in the context of the entire information environment (Van de Sompel & Hochstenbach 1999a). For instance, for a given link-source record from an abstracting & indexing database, extended services can -amongst others -be the presentation of: the full-text of the paper that is abstracted in the link-source; a record abstracting the same publication taken from another abstracting &