Properly delete graphs when resources are deleted from Fedora

[Conal-Tuohy]

Currently when a binary resource is created, the handler script is notified, and it creates or updates one or more corresponding resources in the graph store.

• If the Fedora resource was RDF, it is retrieved and stored in the graph store with the same URI.
• If the Fedora resource was a binary resource, then its metadata resource (whose URI is the same as the URI of the resource, with '/fcr:metadata' appended) is retrieved and stored in the graph store which the same URI (i.e. ending in '/fcr:metadata`).
  • If the binary resource is CSV then the graph store is queried to find a linked CSV Metadata resource, then RDF is generated using that CSVM resource and the result is stored in the graph store under the CSVM resource's URI.
  • If the binary resource is CSV Metadata then RDF is generated using that CSVM resource and the result is stored in the graph store under the CSVM resource's URI.
  • Other binary resources (JPG, PDF, etc) don't currently produce an RDF graph in the graph store.

Currently, when the handler script receives notification from Fedora that a resource has been deleted, it always asks Fuseki to delete the Named Graph whose name is the URI of the deleted resource. However,

• there may not be a corresponding graph to delete (e.g. for a PDF file)
• the fcr:metadata resources are not deleted