Wikibase/Federation/ja
What is federation? What role does it play in the Wikibase Ecosystem?
We say that autonomous systems are federated when they’re connected in a way that lets them share or reference each other’s entities without duplicating data. Any Wikibase instance, including Wikidata, represents a fine example of such an autonomous system. We have two types of federation:
- Ontology Federation
- Query Federation
Ontology Federation
In ontology federation, individual systems (Wikibase instances) share data across the ecosystem in different ways. Sharing data obviates the need for duplicating the data locally that sits on a remote instance; it also reduces management effort. Ontology federation comes in two forms: federated statements and entity matching.
Federated Statements
With federated statements, the local instance refers to data on a remote instance. Here, the local Wikibase regards the remote Wikibase to be authoritative on the data it contains. Each instance has no local data in common with the other. So, we can use a remote property in a statement and use a remote item as a value in a statement. In this context, we define “remote” as a property or item from another Wikibase instance (like Wikidata).
Entity matching
In entity matching, a local instance matches its entities with those of a remote, related instance for easier interoperation. The instances share metadata, but the data itself is not duplicated across instances.
This feature is already in use for Wikidata and Wikibases with external identifier or URL as property data type. Using this feature, a local entity is referenced to another entity on a different instance to connect them, since both entities mean the same thing. It can also be used to reference entities on other knowledge graphs or data stores not part of the Wikibase ecosystem (such as ISBN catalogs, the IMDB, library data stores, etc.)
Query federation
Simply put, federated queries are queries that span multiple instances. Each instance referenced has its own prefix that makes it unique inside the SPARQL query.
In brief, federation means sharing information between Wikibase instances (very much including Wikidata) in order to broaden the base of available data and to prevent the creation of duplicates and the siloization of data.
Expanding federation and interconnection between Wikibases is part of Wikimedia Deutschland's 2021 & 2025 Linked Open Data strategy.