What was Wikibase “Federated Properties”
The “Federated Properties” feature allows / allowed a local Wikibase instance to access and utilise properties directly from a remote Wikibase, primarily Wikidata. Its primary purpose is to enable partial federation between a local Wikibase and Wikidata, broadening the base of available data without needing to create a property set from scratch.
I’m split between using the present and past tense here, as all of this code still exists within the Wikibase extension, however no one has used it since 2022, and it certainly doesn’t seem to be on the short or medium term (or maybe even long term) roadmaps.
This overview comes from the Wikibase – Federated Properties Phabricator project, which I’ll quote the whole of here for prosperity.
Federated Properties v2 (2021)
An initiative to give users the ability to access remote properties from their local Wikibase and use them in combination with custom local properties. The primary use case is enabling partial federation between a Wikibase and Wikidata. This version of the feature will allow you to:
- Opt-in to use Wikidata’s properties in addition to your own custom local properties
- Create and view statements about local entities that contain both local and federated properties
- Query your Wikibase using both local and federated properties
Federated Properties v1 (2020-2021)
An initiative to give users the ability to access remote properties from their local Wikibase (no local properties were possible in this MVP). This version was launched in the Wikibase Spring Release in May 2021.
As far as I remember, the project died with v2, and I don’t even recall if v2 really saw the light of day outside WMDE internal testing and or hidden testing on wikibase.cloud.
A rough timeline of the feature development and testing would be something like this:
- Early 2020: Development began on Federated Properties for Wikibase
- Later 2020: The first version (v1) of Federated Properties was launched as part of the Wikibase Spring Release, compatible with MediaWiki 1.35. This initial version allowed a newly created Wikibase instance to use existing properties from Wikidata or another Wikibase, but it came with a significant limitation: local properties could not be used once federation mode was enabled
- May 2021: The Federated Properties functionality (v1) became available on WBStack / wikibase.cloud. However, the setting was accompanied by a warning, highlighting its limitation of not supporting custom local properties alongside the federated ones
- 2021 Roadmap: A next iteration, Federated Properties v2, was planned for 2021. This version aimed to allow users to opt-in to use Wikidata’s properties in addition to their own custom local properties.
- Throughout 2021, development on v2 was continued.
- August 2022: The Wikibase.Cloud platform removed the “unusable greyed-out Federated Properties configuration section” from its UI, indicating a lack of full or usable support for the feature on this specific cloud offering
I looked through a bunch of old Phabricator tickets, and managed to find a few pictures of the feature being tested out during development, which I have now uploaded to Commons so they can be more easily found in the future.
EDIT 08/08/2025: Turns out I managed to enable the feature on cloud and take some more pictures.
The feature was meant to provide an easy, user-friendly built in way to make connections between wikibases, without needing to think about it too hard as a user. However it seems that these days the majority of the ecosystem is now opting for creating local statement that map to properties on another wikibase via something such as sameAs.
This was already a known pattern during the initial development of this “federated properties” feature, however its hard to redirect a heavily planned organizational roadmap when the train has already left the station.
Likely, most of what is above should be thrown away, and instead user features developed to make linking between wikibases using mappings much easier:
- Bring the idea of doing this up as a first level concept
- Make discovering wiki bases to link to easier
- Integrate this idea throughout other systems, such as the query service to facilitate querying
This was indeed a very weird project 😅
It sure was a fun prototype in the end, and to be honest, it’s rather sad that still to date the ecosystem hasn’t played around with it (through no fault of its own).
However, even prior to day 1 of writing any code for it, it was already clear that doing mappings was likely the way forward, as too much time has passed between initial inception and implementation, and the ecosystem had thus already come up with some patterns that worked well enough, and those would not work with the idea of the “federated properties” feature.
My sense was that this was bound to fall on deaf ears in the community for its two possible use cases:
v1 was only interesting for people who wanted to integrate with Wikidata and do that in some kind of sandbox setting. Re-using Wikidata’s datamodel for anything not Wikidata makes little sense, since it is not an ontology, but the result of community deliberation. But piloting your data in a separate Wikibase is only meaningful when you need to make a lot of manual edits beforehand, and even then, getting the data out of Wikibase and into Wikidata would have been an extra burden.
When you run your own Wikibase and want to federate, you’re probably in the game for Linked Open Data rather than Wikibase. LOD already has established ways of property mapping, but that’s not how this extension was designed to work. Using that extension would instead prevent you from federating with multiple remote resources in a unified manner.
The mis-analysis in my opinion was that people with new Wikibases suffered from empty page anxiety: they had to come up with their own data model for their use case. People deeply embedded in the Wikidata community wanted to help out by offering Wikidata properties as a starting point. I guess what would have helped would have been data model templates for ontologies users asked for, like CDOC-CRM (still kind of impossible to express on top of Wikiase), or a way to separate data model from data so that it could be separately exported an imported.
When I run some wiki as my hobby, I wished this feature until I changed my mind to use a third party extension, UnlinkedWikibase. Thank you for posting this, I have seen what happened a little.
Did this project really start in 2020? Wasn’t it already some years in the making when I left WMDE in 2019?
I certainly think it was some years in the thinking, but implementation didn’t start until 2020 from what I can remember / lookup.
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