In order to consider Fedora's REST API functionally complete, we need to have built-in support for adding, modifying, and removing RDF relationships.

Notes from 11/3 Committer Meeting

HTTP PUT/POST to RELS-EXT/INT.
SPARQL Update
URL Parameter, "kind of update" (possibly could be trigger)
....could be alternative to mime type (some clients can't control headers well)
Validation would happen.
Have it use fedora-system:sdef...accept a POST.
Doesn't require that we do it in the general case.
PUT should be idempotent (to replace the entire datastream)
POST has no such requirement (so to add/delete specific relationships)
Important: Make sense of it for users