Digital library interoperability at high level of abstraction

•Foundational models for digital libraries.•Interoperability among digital library systems and possible approaches.•Unifying semantic model and ontology for high-level interoperability among digital library systems.•In depth analysis of the user, content, functionality and quality domains in digital libraries.•Concrete use case on annotation of illuminated manuscripts to illustrate how to apply the proposed methodology.

Digital Library (DL) are the main conduits for accessing our cultural heritage and they have to address the requirements and needs of very diverse memory institutions, namely Libraries, Archives and Museums (LAM). Therefore, the interoperability among the Digital Library System (DLS) which manage the digital resources of these institutions is a key concern in the field.DLS are rooted in two foundational models of what a digital library is and how it should work, namely the DELOS Reference Model and the Streams, Structures, Spaces, Scenarios, Societies (5S) model. Unfortunately these two models are not exploited enough to improve interoperability among systems.To this end, we express these foundational models by means of ontologies which exploit the methods and technologies of Semantic Web and Linked Data. Moreover, we link the proposed ontologies for the foundational models to those currently used for publishing cultural heritage data in order to maximize interoperability.We design an ontology which allows us to model and map the high level concepts of both the 5S model and the DELOS Reference Model. We provide detailed ontologies for all the domains of such models, namely the user, content, functionality, quality, policy and architectural component domains in order to make available a working tool for making DLS interoperate together at a high level of abstraction. Finally, we provide a concrete use case about digital annotation of illuminated manuscripts to show how to apply the proposed ontologies and illustrate the achieved interoperability between the 5S and DELOS Reference models.