Enhancing interoperability of SPARQL endpoints: RESTful and OAI-PMH API for the DH-ATLAS project

Digital repositories leveraging RDF and Linked Data for Cultural Heritage metadata face a critical challenge: their native SPARQL endpoints often create silos because major aggregators rely on the OAI-PMH protocol for harvesting, and developers prefer RESTful APIs. This divergence undermines the visibility and FAIRness (Findable, Accessible, Interoperable, Reusable) of scholarly resources. This paper details the unified access strategy implemented for the DH-ATLAS project, which generated an Ontology and Knowledge Graph focused on Italian Digital Cultural Heritage research. To ensure broad dissemination and resource reuse without duplicating data, DH-ATLAS developed two configurable and modular software components to implement compatibility with the OpenAIRE guidelines and REST clients. Together, these components establish a cohesive and reusable solution for integrating semantic repositories with diverse metadata consumers, promoting the long-term sustainability and broader accessibility of the DH-ATLAS Knowledge Graph and serving as a model for other RDF infrastructures.