A Common Grammar for Diverse Vocabularies: The Abstract Model for Dublin Core

In its tenth year, the Dublin Core Metadata Initiative has published the “DCMI Abstract Model” (DCAM) as a syntax-independent basis for interoperability of metadata across a diversity of technologies and implementation platforms. Developed since 1997 in parallel with related W3C standards, the DCAM provides a praxis-oriented model for describing resources and for carrying descriptions of multiple resources — i.e., a Dissertation, its Author, and the author’s Institution — in exchangeable records. The model associates properties with resources in a way designed to facilitate the creation of mappings and the merging of metadata from a diversity of sources into cross-domain portals and repositories. By design, the model is also compatible with more complex and expressive ontology languages.

Underlying the DCMI approach are several practical insights: The first is that in our complex, multi-lingual world, it is realistic to limit expectations for shared understanding (“semantic interoperability”) to a pidgin-like core of generic concepts. The second is that metadata based on complex, hierarchical schemas is difficult to re-use outside a specific application context unless it was pre-designed to be mapped to simpler models.

This approach to interoperability — a focus on core semantics on the basis of a modular, generic model — is of more general use than for describing resources with the well-known, fifteen-element “Dublin Core.” The approach is also reflected in standards such as “SKOS Core,” an RDF vocabulary for translating existing thesauri (and other Simple Knowledge Organization Systems) into a form usable for intelligent processing. Sharing a model allows implementers to draw on a diversity of vocabularies — DC, SKOS, and vocabularies more specialized or application-specific — as needed, in creating “application profiles” that reflect requirements and content-level agreements (“cataloging rules”) within particular implementation communities. Sharing a common model also allows different communities to maintain vocabularies which themselves remain small and manageable, yet when combined in application profiles may be highly expressive.

Having achieved a stable model, DCMI is shifting the emphasis of its activities to that reviewing real-world profiles which can be used as good-practice examples by designers of new applications.