Share data to a SPARQL endpoint

[ffsinger]

There should be a "share" button that uploads the RDF data of the user to a file on the SPARQL endpoint. This can be done with an INSERT query.

[ffsinger]

Current progress (f9da969):

• The endpoint can be run on the command line like this: npx comunica-sparql-file-http --update -p 3001 file.ttl
• There is a module (utils/endpoint.js) for sending queries and updates (SELECT, INSERT DATA, INSERT WHERE) to the endpoint
• A share button is available on the interface, the user can use it to send the generated RDF data.

Faced issues:

• Inserts do not work correctly

Experimentations:

• SELECT/CONSTRUCT queries work correctly, either via the app, the command line, or curl
• INSERT queries made via the app raise an error in the library fetch-sparql-endpoint. There may be a bug in the library itself. The error is raised before even sending the request to the endpoint.
• INSERT queries made via the command command line (e.g. by running npx comunica-sparql https://fragments.dbpedia.org/2016-04/en --to http://localhost:3001/sparql "INSERT { ?s ?p ?o. } WHERE { SELECT * WHERE { ?s ?p ?o } LIMIT 10 }") hit the endpoint but raises Actor [...] could not detect a destination with 'application/sparql-update' as 'Accept-Patch' header
• INSERT queries made via curl (curl -X POST -d 'update=INSERT%20DATA%20%7B%20%3Chttp%3A%2F%2Fschema.org%2FOrganization%2F%2540Apple%3E%20%3Chttp%3A%2F%2Fschema.org%2Fname%3E%20%22Apple%22%20.%20%7D' http://localhost:3001/sparql) hit the endpoint with a "400 Bad request" and raises Actor [...] received an invalid rdfjsStore.

[ffsinger]

As mentioned in comunica/comunica#796 :

At the moment, only in-memory updates are supported (to RDF/JS stores).
Other types (LDP, SPARQL GSP, local file, ...) can easily be added in the future by hooking on to the rdf-update-quads bus.

In other words, what we want to do (updating local files) is not supported yet. We will probably have to find a different implementation for the endpoint.

[ffsinger]

Due to a bug in a dependency of a dependency of Comunica, sending update requests to the endpoint does not work when we are in browser mode. The problem is not the endpoint, it's the Comunica client.

The issue is known (mysticatea/abort-controller#32) but it seems that the maintainers are dead.

[pdehaye]

My understanding of the above is that there are thus two problems with Comunica (or a dependency) relating to INSERTs. Both to receive and to send INSERTs. The problems thus have nothing to do it seems with the deployment mode (in browser, server, etc).

[ffsinger]

Progress is on branch https://github.com/hestiaAI/hestialabs-experiences/tree/revised-sharing, closing for inactivity