Resource Description Framework: Achieving interoperable metadata on the Internet

The evolution of the Internet as a global agora for electronic communication and information requires common, standard architectural components. The World Wide Web Consortium (W3C) is the standards organization designed to provide the necessary components to enable continued evolution of the Web. Formal involvement of the OCLC Office of Research in W3C standards work began in 1996 with informal ties to earlier Web standards activities.

In 1996, the W3C was working on an early metadata architecture in their Platform for Content Selection Initiative (PICS). PICS provided mechanisms for communicating simple labels associated with Web pages from a server to clients. These labels generally were designed to contain simple information about the content of Web pages, for example, whether a particular page contains a peer-reviewed research article, or was authored by an accredited researcher, or contains sex, nudity, violence, foul language, etc.

Instead of being a fixed set of criteria, PICS introduced a general mechanism for creating labeling systems. Different organizations could rate content based on their own objectives and values, and users--for example, parents worried about their children’s Web usage--could set their browsers to filter out any Web pages not matching their own criteria. Development of PICS was motivated by the anticipation of restrictions on Internet content.

Through a series of meetings with the digital library community, limitations in the PICS specifications were identified, and functional requirements were outlined to address the more general problem of associating descriptive information with Internet resources based on the PICS architecture. As a result of these discussions, the W3C formed a new working group, PICS Next Generation (PICS-NG), to address the more general issues of resource description. W3C invited OCLC to formally participate in these activities and in 1996, OCLC became a formal W3C member.

Shortly after the PICS-NG working group was chartered, it became clear from many people involved that the infrastructure designed in the early document specifications was applicable in several additional, more general descriptive applications. As a result, the W3C consolidated these working groups focusing on these specific applications into the W3C Resource Description Framework working group whose charter included a more general solution for a metadata architecture for the Web.

The W3C Resource Description Framework plays an important role in enabling a wide range of new metadata applications including sitemaps, stream channel definitions, search engine data collection (Web crawling), digital library collections and distributed authoring. RDF is the result of a number of metadata communities bringing together their needs to provide a robust and flexible architecture for supporting metadata on the Web.

The effort of this working group over the next two years led to the release on Feb. 22, 1999, of the W3C’s final recommendation for a new standard, the Resource Description Framework (RDF). With this event, the goal of interoperable metadata on the Internet is more likely to be reached in the near term. Important Internet-based businesses, representing a variety of user communities including OCLC and its membership, will be implementing the RDF model in their systems, helping to make it real.

For OCLC, the publication of the final recommendation for RDF affords the opportunity to implement its use in several metadata applications including Dublin Core and CORC. The adoption of RDF in CORC makes solid its position as a standard syntax for metadata transfer within the library community, and which in turn should enhance the standing of RDF in the Internet community as a whole.

When OCLC began work on the W3C PICS working group, the CORC project was still two years in the future for OCLC. Yet the resulting recommendation for interoperable metadata that members of the RDF working group created will have a large impact on the eventual usability of the CORC system across the Internet community.

With a sound understanding of what is important to the library community combined with some reasonable amount of monitoring current trends, making the decision to travel a path such as the production of standards for metadata transfers on the Internet is not hard. No one could predict the exact shape of the world of 1999 sitting in late 1996. But it was possible to know that having interoperable metadata technology in place in the next two or three years would help OCLC to support its members with state-of-the-art technology.--Eric Miller is research scientist, OCLC Office of Research.