c# - 获取 Virtuoso 中的本体列表及其属性和类

Question

是否有任何地方（例如对象VDS.RDF.Ontology）保存集成在 OpenLink Virtuoso 实例中的本体列表（及其属性和类）？

我在C#（我使用dotNetRDF）中编程并且我犹豫是否使用查询来获取此信息。

有什么建议么？

Answer 1

In the RDF universe, an ontology is just another graph; each graph should be self-describing; and each ontology graph should therefore include a statement that basically says "I'm an ontology."

Presuming such best practices have been followed, you can use a query like this to get a list of ontology named graphs that are described behind a given endpoint --

PREFIX  owl:  <http://www.w3.org/2002/07/owl#> 
PREFIX  rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 

SELECT DISTINCT ?ontology
WHERE { ?ontology  rdf:type  owl:Ontology }
ORDER BY ?ontology

Note however that it is not necessary for an Ontology graph to be loaded into Virtuoso (or other quad/triple/RDF store) in order for that ontology's terms to be used in other graphs loaded into that store, so I wonder at the purpose of your question...

ETA: Given that you have a list of named graphs for the ontologies in a given instance, you can get their content with queries like this --

SELECT * 
FROM <http://purl.org/vocab/relationship/>
WHERE { ?s ?p ?o }

-- which you can execute through an ADO.NET connection from C#, through the Virtuoso ADO.NET Provider, by turning it into SPARQL-in-SQL a/k/a SPASQL with the simple prepending of the SPARQL keyword and appending of a semicolon --

SPARQL
SELECT * 
FROM <http://purl.org/vocab/relationship/>
WHERE { ?s ?p ?o } ;

It may now go without saying, but to be clear -- you can also issue the initially described query as SPASQL via ADO.NET --

SPARQL
PREFIX  owl:  <http://www.w3.org/2002/07/owl#> 
PREFIX  rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 

SELECT DISTINCT ?ontology
WHERE { ?ontology  rdf:type  owl:Ontology }
ORDER BY ?ontology ;

(ObDisclaimer: I work for OpenLink Software, producer of Virtuoso.)