http://docs.openlinksw.com/virtuoso/rdfandsparql.html RDF Data Access and Data Management OpenLink Virtuoso Universal Server: Documentation virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com 2012-04-25T15:27:44Z OpenLink Software Documentation Team http://docs.openlinksw.com/virtuoso/../images/misc/logo.jpg http://docs.openlinksw.com/virtuoso/rdfdatarepresentation.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com Data Representation 2012-04-25T15:27:44Z Data Representation This section covers how Virtuoso stores RDF triples. The IRI_ID built-in data type is introduced, along with the default table structures used for triple persistency. These details are mostly hidden from users of RDF, thus this section is not necessary reading for typical use of Virtuoso with RDF. http://docs.openlinksw.com/virtuoso/rdfsparql.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com SPARQL 2012-04-25T15:27:44Z SPARQL http://docs.openlinksw.com/virtuoso/sparqlextensions.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com Extensions 2012-04-25T15:27:44Z Extensions http://docs.openlinksw.com/virtuoso/rdfgraphsecurity.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com RDF Graphs Security 2012-04-25T15:27:44Z RDF Graphs Security http://docs.openlinksw.com/virtuoso/rdfviewsrdbms.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com Linked Data Views over RDBMS Data Source 2012-04-25T15:27:44Z Linked Data Views over RDBMS Data Source Linked Data Views map relational data into RDF and allow customizing RDF representation of locally stored RDF data. To let SPARQL clients access relational data as well as physical RDF graphs in a single query, we introduce a declarative Meta Schema Language for mapping SQL Data to RDF Ontologies. As a result, all types of clients can efficiently access all data stored on the server. The mapping functionality dynamically generates RDF Data Sets for popular ontologies such as SIOC, SKOS, FOAF, and ATOM/OWL without disruption to the existing database infrastructure of Web 1.0 or Web 2.0 solutions. Linked Data Views are also suitable for declaring custom representation for RDF triples, e.g. property tables, where one row holds many single-valued properties. http://docs.openlinksw.com/virtuoso/rdfrdfviewgnr.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com Automated Generation of Linked Data Views over Relational Data Sources 2012-04-25T15:27:44Z Automated Generation of Linked Data Views over Relational Data Sources http://docs.openlinksw.com/virtuoso/r2rml.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com Virtuoso R2RML Support 2012-04-25T15:27:44Z Virtuoso R2RML Support http://docs.openlinksw.com/virtuoso/rdfviewsenterpr.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com Examples of Linked Data Views 2012-04-25T15:27:44Z Examples of Linked Data Views http://docs.openlinksw.com/virtuoso/rdfinsertmethods.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com RDF Insert Methods in Virtuoso 2012-04-25T15:27:44Z RDF Insert Methods in Virtuoso http://docs.openlinksw.com/virtuoso/virtuososponger.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com RDFizer Middleware (Sponger) 2012-04-25T15:27:44Z RDFizer Middleware (Sponger) http://docs.openlinksw.com/virtuoso/virtuosospongerfacetinstall.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com Virtuoso Faceted Browser Installation and configuration 2012-04-25T15:27:44Z Virtuoso Faceted Browser Installation and configuration http://docs.openlinksw.com/virtuoso/virtuosospongerfacent.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com Virtuoso Faceted Web Service 2012-04-25T15:27:44Z Virtuoso Faceted Web Service The Virtuoso Faceted web service is a general purpose RDF query facility for facet based browsing. It takes an XML description of the view desired and generates the reply as an XML tree containing the requested data. The user agent or a local web page can use XSLT for rendering this for the end user. The selection of facets and values is represented as an XML tree. The rationale for this is the fact that such a representation is easier to process in an application than the SPARQL source text or a parse tree of SPARQL and more compactly captures the specific subset of SPARQL needed for faceted browsing. The web service returns the SPARQL source text also, thus this can serve as a basis for and-crafted queries. The top element of the tree is <query>, it must be in namespace "http://openlinksw.com/services/facets/1.0/". This has the following attributes: http://docs.openlinksw.com/virtuoso/rdfiridereferencing.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com Linked Data 2012-04-25T15:27:44Z Linked Data There are many cases when RDF data should be retrieved from remote sources only when really needed. E.g., a scheduling application may read personal calendars from personal sites of its users. Calendar data expire quickly, so there's no reason to frequently re-load them in hope that they are queried before expired. Virtuoso extends SPARQL so it is possible to download RDF resource from a given IRI, parse them and store the resulting triples in a graph, all three operations will be performed during the SPARQL query execution. The IRI of graph to store triples is usually equal to the IRI where the resource is download from, so the feature is named "IRI dereferencing" There are two different use cases for this feature. In simple case, a SPARQL query contains from clauses that enumerate graphs to process, but there are no triples in DB.DBA.RDF_QUAD that correspond to some of these graphs. The query execution starts with dereferencing of these graphs and the rest runs as usual. In more sophisticated case, the query is executed many times in a loop. Every execution produces a partial result. SPARQL processor checks for IRIs in the result such that resources with that IRIs may contain relevant data but not yet loaded into the DB.DBA.RDF_QUAD. After some iteration, the partial result is identical to the result of the previous iteration, because there's no more data to retrieve. As the last step, SPARQL processor builds the final result set. http://docs.openlinksw.com/virtuoso/rdfsparqlrule.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com Inference Rules & Reasoning 2012-04-25T15:27:44Z Inference Rules & Reasoning http://docs.openlinksw.com/virtuoso/rdfsparqlgeospat.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com RDF and Geometry 2012-04-25T15:27:44Z RDF and Geometry A geometry may occur as an object of an RDF quad. The SQL MM functions can then be used for geospatial queries. For geometry functions, see the SQL Geometry support section. A geometry may occur as an object value in an RDF quad. In such a case, the bare geometry object is not used but instead a special RDF typed literal is made with the type virtrdf:Geometry. Such a literal is automatically indexed in an R tree index containing all distinct geometries occurring in any quad of any graph under any predicate. Normally, WGS84, SRID 4326 is the SRID of any such geometry. http://docs.openlinksw.com/virtuoso/rdfperformancetuning.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com RDF Performance Tuning 2012-04-25T15:27:44Z RDF Performance Tuning For RDF query performance, we have the following possible questions: http://docs.openlinksw.com/virtuoso/rdfnativestorageproviders.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com RDF Data Access Providers (Drivers) 2012-04-25T15:27:44Z RDF Data Access Providers (Drivers) http://docs.openlinksw.com/virtuoso/rdfgraphreplication.html virtuoso.docs@openlinksw.com virtuoso.docs@openlinksw.com RDF Graph Replication 2012-04-25T15:27:44Z RDF Graph Replication The following section demonstrates how to replicate graphs from one Virtuoso instance to (an)other Virtuoso instance(s), using the RDF Replication Feature. Terms used in this section: The basic outline: