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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 (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: 
    Organization Address: 
    Contact Name: 
    Contact Phone: 
    Contact Email: 
  • bag command will add 

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

Optional Tag Files

Duracloud Bridge:

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

Each optional file is digested and added to the tagmanifest. Validation on optional files is not currently supported.

Unaccepted Tag Files

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



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