BagIt is a specification for packaging/storing content for preservation and transfer. For Chronopolis, we use the bagit specification as a base, only updating certain files to be required.

Structure

Bag Structure
<Collection-Name>/
         |   bagit.txt
         |   manifest-sha256.txt
         |   bag-info.txt
         |   tagmanifest-sha256.txt
         \--- data/
               |   [payload files]

Currently we require sha256 for Chronopolis, so all manifests are appended with "-sha256"

Data Files

The data files (or, the payload of a bag) in the BagIt spec  are all the files found under the data directory. If there are orphaned files (those not found in the manifest, but exist in the data directory), a bag is deemed to be invalid.

Tag Files

Tag files are all those in that exist outside of the data directory. The bagit.txt and bag-info.txt files are standard and we follow the same requirements as in the bagit specification for them.

manifest-sha256.txt

• Required as part of the bagit spec
• Contains the digest of a file with the relative path from the bags root directory
• Uses the same output as the md5sum/sha256sum command line utilities

tagmanifest-sha256.txt

• We require the existence of a tagmanifest, which contains the digest of each tag file and the manifest.
• This lets us validate not only the tag files but also the manifest we were given.
• When doing bagging ourselves, we create this only if each file in the manifest has been validated

bag-info.txt

• Required for UCSD deposits.

• Information listed should come from the UCSD depositor SLA.

  Source Organization: SIO Geological Collections Organization Address: 2310 Downwind Way Contact Name: Alexandra Hangsterfer Contact Phone: 858-822-4837 Contact Email: ahangsterfer@ucsd.edu

  
  

• bag command will add 

  Payload-Oxum: 163450283.76 Bagging-Date: 2017-10-05 Bag-Size: 155.9 MB

  
  

Optional Tag Files

Duraspace:

• manifest-md5.txt
• content-properties.json
• .collection-snapshot.properties

DPN:

• dpn-tags/dpn-info.txt
• Possible other node related tag files

Each file is digested and added to the tagmanifest. DPN has its own constraints on the dpn-info.txt file which we conform to.

Unaccepted Tag Files

• fetch.txt files are not accepted into Chronopolis (although legacy examples may exist)