Open Linking in the Scholarly Information Environment Using the OpenURL Framework

This paper provides insights into the concepts underlying the OpenURL framework for open reference linking in the web-based scholarly information environment. The discussion starts by briefly reiterating the problems with reference linking that were initially described and later addressed as part of the SFX research. Some notions crucial to the understanding of the issues at stake are briefly described: extended service-links, closed and non-context-sensitive linking, open and context-sensitive linking. Then, the paper details the OpenURL framework and reports on its current deployment in the scholarly information environment. As an illustration of the penetration of the OpenURL framework, special attention is accorded to a prototype in which the OpenURL framework is integrated with the DOI/CrossRef linking solution. Introduction This paper provides insights into the concepts underlying the OpenURL framework for open reference linking in the web-based scholarly information environment. The OpenURL framework has its roots in the SFX-research conducted by Herbert Van de Sompel and his colleagues at Ghent University, Belgium, from 1998 to 2000. This discussion starts by briefly reiterating the problems with reference linking initially described and later addressed as part of the SFX research. Notions at the core of the SFX research are described: extended service-links, closed and non-context-sensitive linking, and open and context-sensitive linking. Next, the paper details the OpenURL framework for open linking and reports on its current deployment in the scholarly information environment. A key component in the OpenURL framework is the OpenURL. The OpenURL provides a standardized format for transporting bibliographic metadata about objects between information services. As an illustration of the ongoing interest in the OpenURL framework, special attention is accorded to a prototype in which the OpenURL framework is integrated with the DOI/CrossRef linking solution. This paper focuses on concrete solutions, leaving International Spring School on the Digital Library and E-publishing for Science and Technology CERN, Geneva, Switzerland, 3 – 8 March 2002 16.2  2001 H. Van de Sompel and Oren Beit-Arie is integrated with the DOI/CrossRef linking solution. This paper focuses on concrete solutions, leaving more abstract dimensions of the context-sensitive resolution mechanisms for a forthcoming paper. Extended service-links The term extended service-link was introduced (Van de Sompel and Hochstenbach 1999a) to refer to a link in scholarly information resources that goes beyond the classic notion of a reference link, which is typically understood to be a link from metadata to the full-content described by the metadata. The notion of extended services was introduced to refer to a bundle of such extended service-links, thereby stressing that: • Many services that go well beyond the classical reference link can be delivered for a given metadata description; • Delivery of such services becomes increasingly important to adequately navigate the web-based scholarly information environment. Extended service links that are commonly encountered when exploring scholarly digital libraries lead: • From a record in an abstracting and indexing database (A&I) to the full-text described by the record; • From a record describing a book in a library catalogue to a description of the same book in an Internet book shop; • From a reference in a journal article to a record matching that reference in an A&I database. More creative extended services can be imagined, and have already been introduced in operational environments that use the SFX server software. Such service links lead: • From a citation in a journal article to a record in a library catalogue that shows the library holdings of the cited journal; • From a journal title to impact factor information in ISI's Journal Citation Reports; • From a stock ticker symbol found in a record from the ABI/Inform database to on-line stock information; • From title words or subject headings of a scholarly article to related information in Internet search engines. Closed and non-context-sensitive linking frameworks It has been argued (Van de Sompel and Hochstenbach 1999a) that the way in which the information industry provides such extended service-links is not satisfactory because the manner in which this is done is: • Non-context -sensitive: the established linking frameworks provide service-links that fail to take into account the context of the user who follows a link; • Limited in scope: the established linking frameworks are narrowly focused, both regarding the types of extended services that are being provided as well as regarding the action radius of those links, which is often limited by the scope of business agreements between information providers; • Closed: the established linking frameworks do not allow third parties -such as the user's library -to compensate for these problems by enabling the delivery of self-defined context -sensitive extended service-links. Therefore, such linking frameworks have been referred to as closed and non-context-sensitive linking frameworks. Although these terms have quite different meanings, they have frequently been used as synonyms to refer to the combination of the problems described above. International Spring School on the Digital Library and E-publishing for Science and Technology CERN, Geneva, Switzerland, 3 – 8 March 2002  2001 H. Van de Sompel and Oren Beit-Arie 16.3 A specific instance of the problems introduced by non-context-sensitive linking frameworks is known as the appropriate copy problem for links to full-text (Caplan and Arms 1999). This problem refers to the fact that such linking frameworks fail to provide links that lead from a citation of a journal article to the appropriate full-text copy of that article. A full-text link typically leads to a publisher-defined default copy of the article, which usually resides in the publisher's repository. However, access to the copy of the article that is appropriate in the context of a certain user may very well require the provision of an alternative link: • The user's library may hold a subscription to the electronic journal in which the article was published via an intermediary service. In this case, resolving the reference link to the publisher's default copy may result in a denial of access, because the publisher may not be directly aware of each individual entitled to have access to the desired article. Still, via the library's subscription, the user has legitimate access to the content of the article. In this example, the alternative resolution must take into account the fact that this particular user is allowed to access the article via an intermediary, not directly via the publisher. Hence, the resolution of the reference link must lead to the intermediary's services, where an alternative copy of the article may reside, or where access to the publisher's copy may be cleared. • The user's library may store a copy of the article in a local repository. Again, resolving the reference link to the publisher's default copy may result in a denial of access. Even if access to the publisher's copy would be granted, such resolution is not the preferred one, because it bypasses the library's motivations to actually store content locally. Hence, the preferred resolution should lead to the appropriate copy of the article in the library's repository. • The user's library may not have licensed access to an electronic copy of the article. However, the library may have other means to provide the required content to the user: it may hold a paper subscription to the journal; it may be able to handle a document delivery request; etc. It has been shown that the appropriate copy problem for links to journal articles is in fact only an instance of a more general problem (Van de Sompel and Hochstenbach 1999a) that -by analogy -could be named the appropriate extended-services problem. This problem refers to the fact that established linking frameworks, in general, fail to take into account the context of the user in the provision of extended service-links. A simple illustration of this lack of context in the provision of extended services can be seen in the information industries' widespread use of the PubMed fullfeatured Entrez link-to mechanism. Publishers take advantage of the Entrez system to include links that lead from references in their articles into the PubMed database. These service-links -leading into the default PubMed implementation of the Medline database -are definitely attractive to the user. However, users may find it more attractive if these links would lead into the appropriate Medline implementation provided by their library to which the users are accustomed. And users may find it even more attractive if additional service links would allow them to look up the reference in their local OPAC system, etc. Many more examples have been given (Van de Sompel and Hochstenbach 1999a, Van de Sompel and Hochstenbach 1999c) that illustrate the common lack of context-sensitivity in operational linking solutions. These problems extend well beyond the appropriate copy problem. The SFX research In response to the dissatisfaction with closed and non-context-sensitive linking frameworks, research has been conducted to design a proper architecture that will address the problems described in the above. In this research, which went by the working title SFX (for Special Effects), the term open and context-sensitive linking framework has conveniently been used to refer to a proposed architecture that could make the difference. In the SFX research on context-sensitive linking, the notion of context has been related directly to a user's institutional affiliation. It encompasses contextual elements such as: • The content that is accessible to the user via the institutional digital library: International Spring School