Collaboration of these three OCFL Extensions¶

This document gives an example of a way to combine the three OCFL extensions to achieve a way to prescribe the properties to be recorded and how to record them for each OCFL object version.

Repository layout¶

In this example, the OCFL repository is structured as follows:

[storage_root]
  ├── 0=ocfl_1.0
  ├── ocfl_1.0.txt
  ├── ocfl_layout.json
  ├── object-version-properties.md
  ├── packaging-format-registry.md
  ├── property-registry.md
  ├── extensions
  |   ├── property-registry/
  |   |   └── config.json  
  │   └── packaging-format-registry/
  │       ├── config.json
  |       ├── packaging_format_inventory.json
  |       ├── packaging_format_inventory.json.sha512
  │       └── packaging_formats
  │           ├── 05b408a38e341de9bb4316aa812115ee 
  │           │    └── ... files describing the packaging_format BagIt/v1.0 ...
  │           ├── 76f773808534f2969d7a405b99e78b11 
  │           │    └── ... files describing the packaging_format BagIt/v0.97 ...
  │           └── 15e5e7397258f296a04219bce1defdff
  │                └── ... files describing the packaging_format DANS BagPack Profile/v1.0.0 
  ├── 0de
  |   └── 45c
  |       └── f24
  |           └── item1
  │               └── 0=ocfl_object_1.0
  │                   ├── inventory.json
  │                   ├── inventory.json.sha512
  |                   └── extensions
  │                       └── object-version-properties/
  │                           ├── object_version_properties.json
  │                           └── object_version_properties.json.sha512
  ├────────────────── v1/
  │                   ├── inventory.json
  │                   ├── inventory.json.sha512
  │                   └── content/
  │                        └── ... files ...
  │
  ├────────────────── v2/
  │                   ├── inventory.json
  │                   ├── inventory.json.sha512
  │                   └── content/
  │                        └── ... files ...

Content of the extensions¶

Property registry¶

The config.json file in the property-registry extension declares the properties that can be used in the object_version_properties.json file of an OCFL object version.

{
  "extensionName": "property-registry",
  "propertyRegistry": {
    "retentionEndDate": {
      "description": "the date until which this object version may be retained in this repository",
      "type": "string",
      "constraint": "a date in ISO 8601 format, e.g. 2030-10-01",
      "required": false
    },
    "deaccessioned": {
      "description": "If present, this version of the object has been deaccessioned and should not be disseminated",
      "type": "object",
      "required": false,
      "properties": [
        {
          "name": "datetime",
          "description": "The date on which this object version has been deaccessioned",
          "type": "string",
          "constraint": "a datetime in ISO 8601 YYYY-MM-DDTHH-mm-ss format",
          "required": true
        },
        {
          "name": "reason",
          "description": "The reason why this object version has been deaccessioned.",
          "type": "string",
          "required": true
        }
      ]
    }
  },
  "packagingFormat": {
    "description": "The packaging format of the current object version, as defined in the packaging-format-registry",
    "type": "string",
    "required": true
  }
}

Packaging format registry¶

The config.json file in the packaging-format-registry extension defines how to document the available OCFL Object Packaging Formats.

{
  "extensionName": "packaging-format-registry",
  "digestAlgorithm": "sha512",
  "packagingFormatDigestAlgorithm": "md5"
}

The packaging_format_inventory.json file in the packaging-format-registry extension contains the manifest with the available OCFL Object Packaging Formats for this OCFL Repository.

{
  "manifest": {
    "76f773808534f2969d7a405b99e78b11": {
      "name": "BagIt",
      "version": "v0.97",
      "summary": "a hierarchical file packaging format for storage and transfer of arbitrary digital content."
    },
    "05b408a38e341de9bb4316aa812115ee": {
      "name": "BagIt",
      "version": "v1.0",
      "summary": "https://datatracker.ietf.org/doc/html/rfc8493"
    },
    "15e5e7397258f296a04219bce1defdff": {
      "name": "DANS BagPack Profile",
      "version": "v1.0.0",
      "summary": "A DANS specific profile for the BagPack packaging format."
    }
  }
}

The names of the manifest entries are the digests of name + / + version of the packaging format, using the digestAlgorithm defined in the config.json, e.g.,

echo -n "BagIt/v1.0" | md5sum # Output: 05b408a38e341de9bb4316aa812115ee

The files documenting the packaging formats are stored in the subdirectories with the same names.

Object version properties¶

If the object in the example repository had two versions the object_version_properties.json file might look like this:

{
  "v2": {
    "retentionEndDate": "2071-03-18",
    "packaging-format": "DANS BagPack Profile/v1.0.0"
  },
  "v1": {
    "retentionEndDate": "2071-03-18",
    "packaging-format": "DANS BagPack Profile/v1.0.0",
    "deaccessioned": {
      "datetime": "2025-12-31T13:55:00",
      "reason": "Deaccessioned because confidential data was removed"
    }
  }
}

Both versions have a retentionEndDate of 2071-03-18, which is the date until which this object version may be retained in this repository. Both are packaged using the DANS BagPack Profile/v1.0.0 packaging format, which is defined in the packaging-format-registry extension. The first version was deaccessioned on 2025-12-31T13:55:00 because confidential data was removed, and should not be disseminated.