This feature is unreleased, and only available by downloading and building Fedora 4 from Github.
Overview
Within fedora 4, snapshots of the current state of an object may be saved into the version history either through explicit user requests or during each update to that object. The properties or content of a node saved in these version checkpoints may be accessed later to serve as a historical record of the object. Future feature development may allow for easy reversion to prior versions, export of the entire history or other useful actions.
Creating versions
When you wish to save a snapshot of the current version of a node to the version history you can use the REST API.
Version creation is a relatively costly operation. With the ability to create versions whenever you wish, you can develop workflows that maximize the utility of the version history.
Possible strategies include:
- For batch operations, only create version checkpoints once nodes have been ingested, verified and tested.
- For high value but small data such as descriptive metadata entered by subject experts, set a versioning policy to store every modification to capture the entirety of the curatorial endeavor.
- Create snapshot versions that correspond to released versions of content (ie, version X of a shared dataset, controlled vocabulary or collection)
If you wish to save a full history of a node by having versions created every time the node is updated, you can set the property "fedora:version-policy" to "auto-version".
If your needs for digital preservation are highest and you're willing to sacrifice a little bit of performance, you can set up repository-wide automatic versioning.
Viewing old Versions
From the HTML view (or by issuing HTTP GET methods in a browser) you can get the version history of a node by appending "/fcr:versions" to it's base URL.
Turn off Node Versioning
The fedora repository can operate with unversionable nodes as well as versionable nodes. By default, the "mix:versionable" mixin is applied to newly created fedora nodes. This enables versioning (though does not necessarily result in the creation of versions) for that node. Version-related operations will not work against unversionable nodes, an the presence of the "versioning-policy" will have no effect.
To disable versioning, remove mix:versionable from the node type definitions for the fedora:resource node type.
Brute force method: edit fcrepo-kernel/src/main/resources/fedora-node-types.cnd and remove the "mix:versionable" property from "fedora:resource", then run "mvn clean install" in fcrepo-kernel.
