Standards: Oxford Common File Layout

Oxford Common File Layout (OCFL) is a specification for laying out digital collections on file or object storage. It is designed with long-term preservation principles in mind; does not rely on specialised software and avoids the problem of locking data collections into monolithic repositories behind APIs.

• An OCFL Repository is a system of directories laid out on a filesystem using a prescribed layout. Each repository contains one or more OCFL Objects. An object contains an inventory and a set of versioned content directories.
• The metadata describing an OCFL object’s inventory and versions is stored as simple JSON files which are both human- and machine-readable, and can be processed with lightweight scripts.
• The structure inside the content directories is not specified, so any existing collection of files can be deposited into an OCFL repository and later re-exported with its structure preserved.
• OCFL places no restrictions on the file formats of object contents.

OCFL provides

• Robustness against file errors and data corruption
• Efficient versioning and de-duplication
• Immutable data storage

Links

• OCFL website
• OCFL Specification v1.0

Example

Here is a simplified view of an OCFL repository containing two objects, one of which has two versions and one with three:

-   OCFL repository
    -   Object A
        -   inventory
        -   v1
            -   inventory
            -   content
        -   v2
            -   inventory
            -   content
    -   Object B
        -   v1
            -   inventory
            -   content
        -   v2
            -   inventory
            -   content
        -   v3
            -   inventory
            -   content