Cataloging Horizons

Navigating the bibliographic space with linked data

February 12, 2010

Library catalogs have evolved over time as technology has changed. The last 150 years have seen a progression from book catalogs to cards, and eventually, to online catalogs. Each of these changes has provided new capabilities that can be adopted for improved user services. The next step in this evolution is on the horizon, and it will make possible some new and powerful capabilities for information seekers. Like the hypertextuality of the web, technology is being developed today that can help library catalogs become a rich web of data.

This new data organization will permit users to navigate the bibliographic space by following connections between resources and individual elements in resource descriptions, such as authors, publishers, and dates. Curious as to what else was issued by the publisher that year? Want to see how Romeo and Juliet has been adapted through the years? The catalog based on linked data technology will be able to lead users to answers. It will also allow library data to interact with the larger web of information. This means that web pages and information resources such as Wikipedia can have direct links to library data, and users will be able to move easily between the web and library resources.

The technology that will make this possible is being developed under the aegis of the Semantic Web movement, led by the World Wide Web Consortium but with participation of a wide range of information communities. The goal of the Semantic Web is to create a “web of data” that makes use of the information that is currently hidden in documents on the web. The Semantic Web community has developed a basic pattern for representing information as metadata that mimics a simple sentence with a subject, verb, and object.

What makes this simple structure especially powerful for information seekers is that the link between subjects and objects, that is, the “verb,” is meaningful in a way that hyperlinks between documents on the web are not. Instead of a single type of link that expresses only “this links to that,” in the Semantic Web links have meaning. A link can express a relationship such as “is the author of” in a simple statement like “Herman Melville is the author of Moby Dick.” A link can be used for thesaurus relationships like “broader” and “narrower.” It can even express complex social relationships like “Sally would like to meet Harry.”

Making Metadata Interact

Metadata on the web needs to be able to interact well in that highly diverse information landscape. For this reason, clear identification of data elements and of metadata content is encouraged, and the communities that will make their data available need to be able to share their metadata and their metadata definitions in both human-readable and machine-actionable formats. The Semantic Web community is developing standards that will help metadata creators, including libraries, prepare their data for wide use and reuse.

Of course this won’t happen without effort, and perhaps even a little pain. While the outward appearance of library catalogs has changed greatly, the elements that make up the catalog entry for a library resource today are remarkably similar to the ones that were used for catalogs in the early 19th century. Some changes will be needed to prepare library data for this new environment. Fortunately, the groundwork has been laid with the entity-relation analysis of the Functional Requirements for Bibliographic Records (FRBR), and with the use of that model in the work that has gone into the development of the Resource Description and Access (RDA).
This article is adapted from the Jan./Feb. and March issues of Library Technology Reports.

Karen Coyle is a librarian with over thirty years of experience with library technology. She now consults in a variety of areas relating to digital libraries.