In order to facilitate access to and reuse of data, the protocol should be free of charge and open(-source) so that it can be implemented worldwide. Any user with a computer and an internet connection can at least access the metadata.
Well-documented and machine-readable interfaces enable the automatic indexing, querying, and combining of (meta-)data from various datasets. This significantly enhances accessibility.
Use standardised protocols such as HTTP(S), FTP or SMTP and interfaces such as OAI-PMH, REST, SPARQL Endpoints, ResourceSync, or SWORD. Avoid proprietary or commercial communication solutions.
Convert metadata schemas into common formats such as XML, JSON, or RDF and enable their transmission. Document interfaces thoroughly, maintain a registry for interface endpoints where research data can be accessed, and publish these. Provide examples demonstrating how data can be successfully retrieved from various endpoints and combined into new datasets that can be used for new research.
The Linked Open Data service by Cinema Context with well-documented basic queries.