POC: Support SPARQL querying through front-end

[svandenhoek]

Issue

While we offer RDF output, there is no way to currently use that output in Molgenis EMX2 itself. It would be nice to allow for running SPARQL queries without needing external apps. Even better would be if we could allow for including external sources as well.

Solution

Make a proof-of-concept webpage (similar to Graphql API?) that uses https://comunica.dev/ as a base to run queries. Use RDF API as sources.

Things to consider:

• Write full query manually and/or use menu's to select which schemas/tables to query on.
• POC should only support data retrieval/output manipulation. No support for updating actual stored data.
• Consider building custom layout using EMX2 design or wrapper for their web client builder:
  • https://comunica.dev/docs/query/getting_started/query_browser_app/ (download copy and do not depend on external CDN)
  • https://comunica.dev/docs/query/getting_started/setup_web_client/

Alternatives

Implementing a functioning SPARQL endpoint such as Virtuoso.

• These usually require a (specific) triplestore to store the data in, which would create additional complexity (duplicate data + keeping things in-sync).

Additional context

EMX2 generates RDF files based on the given API request (full table, specific rows, etc). A SPARQL querying that harmonizes with such an approach (by directly allowing RDF files as input to query on) is a better fit than needing to load the data into large triplestore-based tools.