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Versa is a data query language in the Resource Description Framework . It is a compact functional programming language whose syntax resembles Lisp when alternative query languages to RDF use a SQL basis, or special XML dictionaries. The development of Versa was inspired by XPath . As of 2005 , there is only a Versa implementation on the Python PP, in the open-source 4Suite XML framework .
Examples
Get the URI (Uniform Resource Identifier) of all known resources:
all ()
Get the URI of all occurrences of type edu:Subject :
type (edu: Subject)
Get the rdfs:label all edu:Subject that have one or more rdfs:label :
type (edu: Subject) - rdfs: label -> *
Get the URI of all edu:Subject with rdfs:label equal to "Russian language" :
type (edu: Subject) | - rdfs: label -> eq ("Russian language")
Get the URI of all "super- edu:Subject s" (transitively) for edu:Subject identified by " http://en.wikipedia.org/wiki/Russian_language " :
traverse (@ " http://en.wikipedia.org/wiki/Russian_language ", @ " http://example.com/education#subTopicOf (inaccessible link) ", vtrav: forward, vtrav: transitive)
Compare with
- DQL , XML- based queries and results in DAML + OIL
- N3QL , based on Notation 3
- R-DEVICE
- RDFQ , XML based
- RDQ , SQL -based
- RDQL , similar to SQL
- SeRQL , similar to SQL, close to RDQL
- SPARQL , similar to SQL, was created as a W3C standard
Links
- Versa home page
- IBM developerWorks: Thinking XML: Basic XML and RDF techniques for knowledge management, Part 6
- XML.com: Versa: Path-Based RDF Query Language
- irc: //irc.freenode.net/versa ; there exists a Versa "IRC bot" [1] , useful for learning, experimentation, and debugging
- RDF query use cases, including query language samples