OCFL Standard in Practice

Abstract

As part of a “Live-Lab,” the creation of OCFL objects with the tool gocfl will be discussed, practically carried out, and tested. This includes a deep dive into the OCFL format (e.g., integrity, naming, versioning, and extensions) as well as typical versioning actions such as deleting, replacing, and renaming content. A focus is placed on OCFL extensions relevant for long-term digital preservation, such as extraction of technical and filesystem metadata, more sustainable filenames, and internal object format migration (including approaches like METS/PREMIS and Trusted Timestamps). The workshop is suitable for spectators but is primarily aimed at participants who want to follow the processes on their own computers; work is done in the terminal, either in a provided container or in your own environment with appropriate prerequisites.

What is OCFL?

The Oxford Common File Layout (OCFL) is an open standard for structuring digital objects in a filesystem or object store. It was developed to ensure the long-term preservation of digital content by providing a robust, complete, and versioned storage method that is independent of specific software infrastructure.

Core Features of OCFL:

Self-Contained: An OCFL object contains all the information necessary for its reconstruction.
Integrity: Every file in the object is protected by checksums (hashes).
Versioning: Changes to objects are efficiently tracked across versions.
Self-Describing: By including the specification and documentation of the used extensions directly in the storage path, the archive remains understandable even without external resources.
Extensibility: The standard allows for specific extensions for additional metadata or functions.

OCFL is often seen as an “intelligent successor” to BagIt. It extends BagIt with versioning, deduplication, and the ability to rename paths and filenames. Within versioning, deletions and renames are supported just as well as adding files.

Structure of OCFL

The standard distinguishes between two basic core elements:

Storage Root: The top level in the filesystem where OCFL objects are stored. It contains administrative information about the OCFL version and the layout used.
Object: A digital object within the storage root consisting of one or more versions of files and metadata.

The Tool gocfl

In this workshop, the tool gocfl is used. It is a tool written in the Go programming language that supports the following functions:

Creation of OCFL objects.
Update of existing objects through new versions.
Validation of objects and storage roots against the specification.
Extraction of content from OCFL objects.
Creation and Management of storage roots.

An overview of the planned workshop course can be found in the Table of Contents (TOC).

Further Information

Further details on the standard and specification can be found on the official website:

je4.github.io