Federated Vocabulary Hubs as a Foundation for Semantic Layers in Data Spaces

This paper proposes a layered architecture for federating vocabulary hubs, the component within a single data space responsible for shared agreement on semantics. Until now, each data space has their own vocabulary hub as prescribed by the IDS-RAM. The proposed design addresses the vocabulary hub federation problem. Moreover, it enables a semantic layer that provides semantic services over these federated data spaces. The European Commission's recent standardization request for a European Trusted Data Framework underlines the relevance of this work. This paper discusses relevance, requirements, like scalability and data sovereignty, and a layered architecture that integrates IDS and Semantic Web standards. Existing tool implementations are discussed that implement parts of the architecture and that can form a basis for future implementation of the full architecture for this semantic layer over data spaces.