+ # callack for register/update
+ # this allows to capture changes in the relations between objects
+ # the ids below are the ones found in the 'pointer' field
+ # this can get typically called with
+ # 'slice' 'user' 'researcher' slice_id user_ids
+ # 'authority' 'user' 'pi' authority_id user_ids
+ def update_relation (self, subject_type, target_type, relation_name, subject_id, link_ids):
+ pass
+