Story: Create an Inventory Process for online Moabs

[julianmorley]

Work out how to:

• scan a storage root for new Moabs, put that info into the PCC/Object Inventory Store. e.g. WHERE the Moab is, WHAT version it is, WHEN we saw it.
• scan a storage root for updated Moabs, update that info in PCC/Object Inventory Store. e.g: Inventory service: "I see Druid zz123bb124 on sdr-services-12/sdr2objects is version 8." PCC/OIS: "The most recent version of that Druid on that storage root that I know about is version 7." Inventory service: "This is an update, then! Let us update our records in the PCC/OIS and tell the archive service that it has work to do."
• Be told by IngestWF that a new or updated Moab has been placed in storage_root, and inventory it (put that info into the PCC/Object Inventory Store).
• Have a way to run a continuous or periodic inventory scan against a given storage root.

[julianmorley]

At this time, this is ONLY for online Moabs. We will solve the problem of inventorying archive Moabs later, perhaps by extending this or by doing something else.

[tallenaz]

Story time notes:

• scan a storage root to find druids, check their version, and write the druid, where it was, when we found it, and what version into the ois
• the process should be constantly trolling the storage roots for the druids
• the process should listen to the IngestWF for whether to add a new/updated druid
• we should be able to use the inventory service to seed and/or recover the oic database
• if we can know that the inventory service has reached a "steady state", query the db for things that have been touched most recently
• for now, we don't need to consider whether the process is triggered periodically or continuously
• both ingest and inventory services, we currently think, can write to the database

pseudo code to try expressing the inventory service and the methods it will need:

# scan storage root for new moabs
# create new moabs in ois
MoabStorage.all.each do |m|
  if InventoryService.preserved_object_exists?(m)
    InventoryService.create(m) # or POST /catalog/add_preserved_object
  end
end

# scan storage root for updated moabs
# update ois if necessary
MoabStorage.all.each do |m|
  moab_version = m.version
  latest_ois_version = m.latest_ois_version
  if moab_version > latest_ois_version
    InventoryService.update(m) # or PUT /catalog/update_preserved_object
  end
end

# be told by ingestWF of a new/updated moab
# put that moab in ois
if IngestWF.new_moab?
  ingest_moab = InventoryService.fetch_ingest_wf_moab # or GET /moab_storage/show/:id
  InventoryService.create(ingest_moab) # or POST /catalog/add_preserved_object
end