They really should extend KVS for this - it's going to be very difficult to leverage if the XSS interface is underneath the filesystem (as shown in the diagram)

They really should extend KVS for this - it's going to be very difficult to leverage if the XSS interface is underneath the filesystem (as shown in the diagram) especially for RDBMS where the database is (usually) a single big flat file as far as the filesystem is concerned.