Fthierygeo: /* Use Case: Ogham */

2026-07-14T13:17:36Z

Use Case: Ogham

← Older revision		Revision as of 13:17, 14 July 2026
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	= Use Case: Ogham =		= Use Case: Ogham (CIIC 81) =

			A single object — the Ogham stone '''CIIC 81 / UCC Stone Corridor IV''' — is described across '''five Wikibases plus Wikidata'''. We tie them together in one hub item ([[Item:Q5\|Q5]]) on this instance.

			== What we mean by federation here ==

			This is the '''hardest need''' the Task Force names: ''"the ability to have statements in one Wikibase on an entity from another Wikibase."'' The stone's facts do not live in one place:

			* '''Wikidata''' — the generic layer: object type (Ogham stone), script (Ogham), find place, current location, collection.
			* '''FactGrid''' (Q1000294) — the inscription reading and related persons.
			* '''Fuzzy-SL''' (Q74) — the (fuzzy) coordinates.
			* '''Semantic Kompakkt''' (Q1247) — the 3D model.
			* '''SquirrelBase''' (Q48) — the FAIR Digital Object + Zenodo DOI.
			* '''LinkedOgham''' (Y50000081) — the LOD record.

			The hub reuses Wikidata for the shared layer and '''links to''' each specialist record for the domain detail — without copying it.

			== Why a Wikibase ecosystem, not Wikidata alone ==

			* The domain detail (inscription epigraphy, fuzzy spatial models, 3D scans, FDOs) is '''too specialised / not notable enough''' for Wikidata. Each community curates its own Wikibase.
			* Federation ties these into '''one queryable graph''' without duplication or drift — the Task Force's "combined querying" and "prevent splits" goals.
			* Concrete example: the inscription ''C[A]SSITT[A]S MAQI MUCOI CALLITI'' stays authoritative in FactGrid. The hub carries only a '''reference''' to it, and a one-hop federated SPARQL query pulls it live at query time.

			== How it works technically ==

			* Generic values: '''native Wikidata value federation''' (e.g. ''instance of'' → wd:Q2016147).
			* Cross-Wikibase links: '''external-id + formatter URL''' per source (e.g. ''FactGrid ID'' = Q1000294, formatter <code>https://database.factgrid.de/entity/$1</code>). This yields a '''resolvable IRI''' in the RDF → traversable by federated SPARQL. This is exactly the Task Force's "external ID back to the source" pattern.
			* Provenance: materialised values (coordinate, inscription) carry a '''reference''' to the source Wikibase.

			== What to watch out for (things we actually hit) ==

			* '''Identifier collisions.''' Q-numbers repeat across instances (FactGrid Q1000294 ≠ our Q1000294). Always normalise to '''full entity URIs''', never bare Q-numbers — this is the Task Force's identifier-reuse warning in practice.
			* '''url datatype is blocked''' on this instance → we bridge with external-id + formatter (string), which also gives the resolvable IRI.
			* '''Federated Wikidata items render as "(Deleted Item)"''' via the API until registered once via the UI (alpha API gap).
			* '''formatterUrlProperty must be set''' server-side, or external-ids do not resolve to IRIs and are not clickable.
			* Cross-Wikibase '''SPARQL federation''' requires the target endpoint on the query-service allowlist.

			== TODOs ==

			* '''[Flo]''' Register the referenced Wikidata items once via the UI so they resolve.
			* '''[Flo/devs]''' Set <code>formatterUrlProperty</code>; unblock the url datatype.
			* '''[Flo/devs]''' Add FactGrid / Fuzzy-SL / Semantic Kompakkt / SquirrelBase endpoints to the query-service allowlist.
			* '''[Flo]''' Curate remaining values; publish the crosswalk.

			== What would matter most for federation ==

			* '''Native Wikibase-to-Wikibase values''' (not just Wikidata) would replace the external-id bridge — the single most valuable extension for this use case.
			* Stable, '''collision-free identifiers''' across the ecosystem.
			* '''Query-service federation''' across the linked instances.

			''See also: [[UseCases/Software]] — the "reuse Wikidata, extend with your own vocabulary" case.''

Fthierygeo: Created page with "= Use Case: Ogham ="

2026-07-14T13:00:52Z

Created page with "= Use Case: Ogham ="

New page

= Use Case: Ogham =

UseCases/Ogham - Revision history

Fthierygeo: /* Use Case: Ogham */

Fthierygeo: Created page with "= Use Case: Ogham ="