Infrastructure

Note that is applies only to test and development activity, not for operations.

There is an MN.delete() method with a note that we should determine what the semantics of this operation are.
For Metacat, "delete" does not remove any content and only prevents it from:
a) being updated by another revision,
b) having the same identifier reused, and
c) showing the object in search results.
If you know the identifier (cited in a paper, say) you can always retrieve it. In DataONE we would set SystemMetadata.archived=true for these items and the change in SystemMetadata should be replicated up to the CN and propagated to all replicas on other MNs.

Reasons for a more forceful "delete" mechanism:
a) Inappropriate content (illegal, copyrighted, too large)
b) Mistake/testing
Since we NEVER want to reuse identifiers, we should maintain a SystemMetadata record for all deleted objects. I would vote to change the SystemMetadata.archived flag to be an optional "status" indicator with initial possible values of "archived" and "deleted" where, if omitted, it would indicate a normal/active object. The MN should propagate this SystemMetadata change to the CN which would spread the word to the other MNs. I think the MNs could remove all trace of that object and rely on the CN to keep a record of the identifier being used (so that it was not reused in the DataONE system). MNs holding a replica could also completely remove the object. This points to a need for MNs to have two methods:
MN.archive()
MN.delete()