April 2008


SWRL (http://www.w3.org/Submission/SWRL/#2.1) is proposal for a semantic web rules-language, combining sublanguage of the OWL Web Ontology Language (OWL DL and Lite) with those of rule markup language (RuleML). The Rule Markup Language (RuleML) is a markup language developed to express both forward (bottom-up) and backward (top-down) rules in XML for deduction, rewriting, and further inferential-transformational tasks.

 

SQWRL (Semantic Query-Enhanced Web Rule Language; pronounced squirrel) is a SWRL-based query language that can be used to query OWL ontologies. SQWRL provides SQL-like operations to format knowledge retrieved from an OWL ontology. SQWRL does not alter SWRL’s semantics and uses the standard SWRL presentation syntax supported by the SWRLTab.

 

Below is the example of SWRL syntax to infer visitor’s location. (more…)

While the command-line sparql tool is useful for running standalone queries, Java applications can call on Jena’s SPARQL capabilities directly. SPARQL queries are created and executed with Jena via classes in the com.hp.hpl.jena.query package. Using QueryFactory is the simplest approach. QueryFactory has various create() methods to read a textual query from a file or from a String. These create() methods return a Query object, which encapsulates a parsed query. (more…)