The Virtual Union Catalog: A Comparative Study

A Virtual union catalog is a possible alternative to the centralized database of distributed resources found in many library systems. Such a catalog would not be maintained in a single location but would be created in real time by searching each local campus or affiliate library’s catalog through the Z39.50 protocol. This would eliminate the redundancy of record storage as well as the expense of loading and maintaining access to the central catalog. This article describes a test implementation of a virtual union catalog for the University of California system. It describes some of the differences between the virtual catalog and the existing, centralized union catalog (MELVYL). The research described in the paper suggests enhancements that must be made if the virtual union catalog is to become a reasonable service alternative to the MELVYL® catalog. RESUMO Um catálogo de união Virtual é uma alternativa possível para o banco de dados centralizado de recursos distribuídos encontrados em muitos sistemas de bibliotecas. Este catálogo não seria mantido em um único local, mas seria criada em tempo real, pesquisando cada campus local ou catálogo da biblioteca da filial através do protocolo Z39.50. Isto eliminaria a redundância de armazenamento registro, bem como à custa de carga e manter o acesso para o catálogo central. Este artigo descreve uma implementação de teste de um catálogo união virtual para o University of Califórnia sistema. Ela descreve algumas das diferenças entre o catálogo virtual e o existente, catálogo união centralizado (MELVYL). A pesquisa descrita no artigo sugere melhorias que devem ser feitas se o catálogo virtual é a união para se tornar uma alternativa de serviço razoável para o catálogo ® MELVYL. ARTIGOS Tema: Biblioteconomia (Tecnologia de Informação e Comunicação Rev. online Bibl. Prof, Joel Martins v.1., n.2, fev. 2000 THE UNIVERSITY OF CALIFORNIA UNION CATALOG The University of California, with its nine campuses located throughout the state, adopted the goal of "One University, One Library" in 1977. Under this goal, the resources of these geographically distributed libraries would be treated as a single collection available to the entire scholarly community of the University. The first step toward this goal was the development of a union catalog for the libraries. After early attempts at a book catalog and a subsequent microfiche version, in 1982 the union catalog came into being as an online public access system known as MELVYL®. This centralized database is built from catalog records sent by all the cataloging departments of participating libraries to the California Digital Library (CDL) where the MELVYL catalog is housed. Participating libraries include the California State Library, the Center for Research Libraries, and a number of affiliated institute libraries. In all, there are twenty-nine separate (and diverse) input streams that feed into the union catalog on either weekly or monthly update schedules. Parallel to the MELVYL database, which contains records for monographs and non-book format materials, is the state of California's union database of serials. This includes serials records for the University of California, the California State Universities, other public and private research libraries such as Stanford and University of Southern California, as well as the union lists of public libraries, law libraries and medical libraries. For this database there are thirty-seven different input streams representing nearly 600 libraries that are updated anywhere from weekly to yearly. FUNCTIONS OF THE UNION CATALOG First and foremost the MELVYL catalog is a document discovery tool for end-users. At a time when most other catalogs were limiting users to left-anchored exact heading matching, MELVYL had keyword searching on titles and subjects as well as a sophisticated personal name algorithm that can retrieve an AACR heading based on a variety of user input. The catalog also turned out to be an important tool for the libraries themselves and was soon incorporated into inter-library loan, collection development and even cataloging functions. One particular aspect of the catalog that has proven to ARTIGOS Tema: Biblioteconomia (Tecnologia de Informação e Comunicação Rev. online Bibl. Prof, Joel Martins v.1., n.2, fev. 2000 have added value beyond our original intentions relates to the unique way that records from different sources are merged and stored. For each unique title we created a merged record that could contain all the uniquely contributed fields by each cataloging source. This means that our underlying record can have multiple 100 or 245 fields, as well as a variety of other USMARC fields. Naturally, we only show the end-user a single view of this record, but all the variant fields in the record can contribute to record access. This means that if a single library adds a subject heading in their own local catalog, when added to the MELVYL catalog that subject heading provides access to all copies of that title. It also means (and this is the part that we didn't anticipate) that if one campus contributes a full catalog record and another creates only a minimal record, the latter library gains all the functionality of the full cataloging of the former. This became an important side effect of our merged record when libraries were undergoing retrospective conversion, and again when AACR2 necessitated updating large numbers of name headings. While not a substitute for bringing their own local catalogs up to date, at least union catalog users were benefiting from efforts made by any library in the University of California system, and the libraries themselves may have had greater options in terms of where to put their limited resources during those times of change. Today, all campuses have integrated library systems and the quality of the records in those systems and input to the MELVYL catalog is quite high. Still, we keep finding new uses for the union catalog. Recently it became the basis for a patroninitiated request system that allows cross-library lending with minimal staff interaction in the ILL departments. The periodicals file is linked in rather clever ways to both locally-mounted and remote abstracting and indexing databases so that users can go from a retrieved citation to a list of libraries that carry the periodical title. The union catalog is also becoming the university's catalog of Internet-accessible resources. THE VIRTUAL UNION CATALOG CONCEPT The current MELVYL centralized database model was developed nearly 20 years ago, prior to the widespread availability of networks and distributed databases. It was also developed before the participating libraries had OPACs of their own. It runs on a large mainframe computer using locally-developed software, some of which is ARTIGOS Tema: Biblioteconomia (Tecnologia de Informação e Comunicação Rev. online Bibl. Prof, Joel Martins v.1., n.2, fev. 2000 actually over twenty years old. Hardware maintenance costs are high and database update and maintenance functions are labor-intensive. As part of an ongoing process of service evaluation, which includes the evaluation of service efficiency and cost effectiveness, studies were initiated to determine if it is reasonable to seek alternatives to the centrally housed union catalog that could achieve many of the same goals of quality user service, 24x7 availability and excellent response time. One possible alternative to the central database is a virtual union catalog. Such a catalog would not be maintained in a single location but would be created in real time by searching each local campus or affiliate library’s catalog through the Z39.50 protocol. This would eliminate the redundancy of record storage as well as the expense of loading and maintaining access to the central catalog. A distributed catalog makes obvious sense in our current environment where every library has its own database and retrieval interface. The wide-spread use of Z39.50 and its implementation in nearly all modern library systems means that there should not be major technological barriers to a distributed solution. Or, so it seems. DISTRIBUTED CATALOGS We are hardly the first to think of, much less implement, a distributed catalog solution. Even just over the last year this technology has moved from the "gee whiz" to the "of course" stage. The ability to send queries to one or more other library catalogs is a regular feature, although the actual implementation details vary. Consortia similar in characteristics to the University of California are actively using this technology. The Committee on International Cooperation (CIC), for example, has published a report of their experience with their virtual catalog implementation. The CIC report expressed some dissatisfaction with the virtual catalog as a discovery tool and advocated more development on the part of library automation vendors. Some of the problems that they encountered were foreseen, such as inconsistency in results between catalogs that had defined their indexes differently, but there was no way to quantify the dis-ease that the librarians at these institutions experienced. The University of California is unique in that we have a current centralized catalog so we can compare the results between these two catalog technologies. ARTIGOS Tema: Biblioteconomia (Tecnologia de Informação e Comunicação Rev. online Bibl. Prof, Joel Martins v.1., n.2, fev. 2000 TEST GOALS Although some of the advantages and disadvantages of the virtual union catalog approach could be anticipated without a test implementation, there is nothing to compare to actual experience with a new technology. And many of the results presented here would not have been foreseen by study of other systems that have attempted the same design. There are no absolute measures of OPAC effectiveness that we could use to evaluate the virtual union catalog, but because we do have a centralized union catalog, we are able to make comparisons between the MELVYL catalog, with which we are familiar, and a virtual union catalog. We expected there to be many differences, so the goal was not to rate the virtual union catalog against MELVYL but to describe the differences and determine if the virtual union catalog could provide a reasonable service alternative to the MELVYL catalog. TEST METHODOLOGY Participants Campus main libraries were contacted and given the opportunity to volunteer to participate in the comparison. For this test, no attempt was made to cover all campus input sources (affiliated libraries, special libraries) or non-UC sources. The assumption was that the "main" library was the best target for our purposes. Six campus libraries chose to participate. These included three different library systems: Innovative Interfaces (four sites), DRA WebCat, and OCLC SiteSearch (one site each). Catalog Search Capabilities A preliminary analysis of the search capabilities for participating systems was performed. Not only did we have three different "brands" of library system to connect to, it's also the case that Z39.50 search capabilities are not the same as local OPAC search capabilities. Indexes available via Z39.50 for the six participating libraries are listed in Figure 1. Note that differences occur not only between library ARTIGOS Tema: Biblioteconomia (Tecnologia de Informação e Comunicação Rev. online Bibl. Prof, Joel Martins v.1., n.2, fev. 2000 system "brands" but also within different installations of the same vendor system due to configuration choices made by the libraries. Figure 1 – Fields Available Through Z39.50 FIELD SiteS DRA III-1 III-2 III-3 III-4 Author X X X X X X