Is it possible to query multiple endpoints at once (for example, Wikidata, Europeana and our own pages) and then represent the returned properties in a map or data table, as it is possible to do with a single endpoint? I wanted to be able to show common properties between these endpoints and each of their entries.
Topic on Extension talk:LinkedWiki
In theory yes... LinkedWiki sends the federated query at one endpoint to execute the the query. After this endpoint communicates with other endpoints to resolve the query. Generally, before, you need to enable "federated query processing" in the database (example with Virtuoso).
Thank you for your answer. Sadly my database is not with Virtuoso but with MySQL. I have not found out yet a way that lets me enable federated query processing without isql.
If I try to do a federated query (simply using "SERVICE<http://sparql.europeana.eu/>{}" I also get the following error:
"Sorry, the sparql server sent an error.
Virtuoso 42000 Error SQ070:SECURITY: Must have select privileges on view DB.DBA.SPARQL_SINV_2 SPARQL query"
I am still quite unexperienced with SPARQL, but my idea was to query properties from both endpoints, such as coordinates, and place them on a leaflet map. I can do this only with one endpoint so far.