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A simple Ruby DSL for creating and working with RDF graphs as regular Ruby objects
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rsinger/RDFObjects
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RDFObjects are intended to simplify working with RDF data by providing a (more) Ruby-like interface to resources (thanks to OpenStruct). There is a Google Group at http://groups.google.com/group/rdfobjects to discuss problems, enhancements, changes, announcements, etc. Installation: The gem is currently hosted at http://gemcutter.org/gems/rdfobjects so you'll either need the gemcutter gem (and run "gem tumble") or add gemcutter.org to your sources manually (gem sources -a http://gemcutter.org). $ sudo gem install rdfobjects Requirements: * Nokogiri (the idea is for more options in the future) * curies * json (or json_pure) Usage: >> require 'rdf_objects' >> include RDFObject >> Curie.add_prefixes! :skos=>"http://www.w3.org/2004/02/skos/core#" >> resource = Resource.new('http://id.loc.gov/authorities/sh2002000569#concept') >> resource.describe >> resource.skos => {"inScheme"=>[#<RDFObject::Resource uri="http://id.loc.gov/authorities#topicalTerms">, #<RDFObject::Resource uri="http://id.loc.gov/authorities#conceptScheme">], "broader"=>[#<RDFObject::Resource skos={"prefLabel"=>"Semantic networks (Information theory)"}, uri="http://id.loc.gov/authorities/sh92004914#concept">, #<RDFObject::Resource skos={"prefLabel"=>"World Wide Web"}, uri="http://id.loc.gov/authorities/sh95000541#concept">, #<RDFObject::Resource skos={"prefLabel"=>"Semantic integration (Computer systems)"}, uri="http://id.loc.gov/authorities/sh2004000479#concept">], "closeMatch"=>#<RDFObject::Resource uri="http://stitch.cs.vu.nl/vocabularies/rameau/ark:/12148/cb14521343b">, "prefLabel"=>"Semantic Web"} >> resource["[skos:prefLabel]"] => "Semantic Web" >> resource.skos["prefLabel"] => "Semantic Web" >> resource["http://www.w3.org/2004/02/skos/core#prefLabel"] => "Semantic Web" (etc.) >> resource.skos["broader"].first.skos["prefLabel"] => "Semantic networks (Information theory)" Unnecessary, but helpful, way to define typed literals >> source = Literal.new("Library of Congress Authorities", {:language=>"en"}) And assert them >> resource.assert("http://purl.org/dc/terms/source", source) => ["Work cat.: 2002070545: The Semantic Web--ISWC 20002, 2002.", "ASTI on FirstSearch, May 6, 2002: in titles (semantic Web)", "Engr. index online, May 6, 2002 (identifier: Semantic Web)", "Library of Congress Authorities"] >> resource["http://purl.org/dc/terms/source"].last.language => "en" To relate a resource to another URI you can use #.relate - it will accept full uri strings, safe curies or other RDFObject::Resource objects >> resource.relate("[skos:closeMatch]", "http://dbpedia.org/resource/Category:Semantic_Web") => [#<RDFObject::Resource uri="http://stitch.cs.vu.nl/vocabularies/rameau/ark:/12148/cb14521343b">, #<RDFObject::Resource uri="http://dbpedia.org/resource/Category:Semantic_Web">] These relationships are actually replaced with RDFObject::ResourceReference objects (to prevent massive recursion errors). To access the actual Resource object, use: >> resource["[skos:closeMatch]"].first.resource => #<RDFObject::Resource uri="http://stitch.cs.vu.nl/vocabularies/rameau/ark:/12148/cb14521343b"> In order to be sure you are always asserting against the same object, use RDFObject::Collection objects to manage your Resources. >> collection = Collection.new => {} >> r1 = collection.find_or_create('http://ex.org/ex/1234') => #<RDFObject::Resource uri="http://ex.org/ex/1234"> >> r1.object_id => 8996290 >> r2 = collection.find_or_create('http://ex.org/ex/1234') => #<RDFObject::Resource uri="http://ex.org/ex/1234"> >> r2.object_id => 8996290 So relationships and assertions are always applied to the same objects. You can delete a single resource: >> collection.remove(r1) >> collection => {} There is also a convenience method on RDFObject::Collection to help find particular resources by predicate: >> resources_with_types = collection.find_by_predicate("http://www.w3.org/1999/02/22-rdf-syntax-ns#type") And to find resources by predicate and object: >> resources_i_want = collection.find_by_predicate_and_object("http://www.w3.org/2004/02/skos/core#closeMatch", "http://stitch.cs.vu.nl/vocabularies/rameau/ark:/12148/cb145537755") Both these return RDFObject::Collection objects with your matches. Changes to resources in these collections also affect the resource in original collection. There are also parsers for ntriples, rdf/xml, RSS 1.0, RDFa, and JSON. Parsers return a RDFObject::Collection with all of the resources discovered in the RDF source. >> resources = Parser.parse(open('lcsh.nt').read) >> resources.values.first => #<RDFObject::Resource n0={"altLabel"=>"Lichen ruber planus", "inScheme"=>[#<RDFObject::Resource uri="http://id.loc.gov/authorities#conceptScheme">, #<RDFObject::Resource uri="http://id.loc.gov/authorities#topicalTerms">], "prefLabel"=>"Lichen planus"}, n1={"sameAs"=>#<RDFObject::Resource uri="info:lc/authorities/sh85076767">}, uri="http://id.loc.gov/authorities/sh85076767#concept", n2={"modified"=>#<DateTime: 211644344801/86400,-1/6,2299161>}, rdf={"type"=>#<RDFObject::Resource uri="http://www.w3.org/2004/02/skos/core#Concept">}> There are serializers for RDF/XML and ntriples. Both resources and collections can be serialized. >> resource.to_xml => "<rdf:RDF xmlns:n0="http://www.w3.org/2004/02/skos/core#" xmlns:n1="http://www.w3.org/2002/07/owl#" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:n2="http://purl.org/dc/terms/"><rdf:Description rdf:about="http://id.loc.gov/authorities/sh85076767#concept"><n0:altLabel>Lichen ruber planus</n0:altLabel><n0:inScheme><rdf:Description rdf:about="http://id.loc.gov/authorities#conceptScheme"></rdf:Description></n0:inScheme><n0:inScheme><rdf:Description rdf:about="http://id.loc.gov/authorities#topicalTerms"></rdf:Description></n0:inScheme><n0:prefLabel>Lichen planus</n0:prefLabel><n1:sameAs><rdf:Description rdf:about="info:lc/authorities/sh85076767"></rdf:Description></n1:sameAs><n2:modified rdf:datatype="http://www.w3.org/2001/XMLSchema#dateTime">1994-08-22T15:46:41-04:00</n2:modified><rdf:type><rdf:Description rdf:about="http://www.w3.org/2004/02/skos/core#Concept"></rdf:Description></rdf:type></rdf:Description></rdf:RDF>" >> collection.to_xml >> resource.to_ntriples => "<http://id.loc.gov/authorities/sh85076767#concept> <http://www.w3.org/2004/02/skos/core#altLabel> "Lichen ruber planus"@en.\n<http://id.loc.gov/authorities/sh85076767#concept> <http://www.w3.org/2004/02/skos/core#inScheme> <http://id.loc.gov/authorities#conceptScheme>.\n<http://id.loc.gov/authorities/sh85076767#concept> <http://www.w3.org/2004/02/skos/core#inScheme> <http://id.loc.gov/authorities#topicalTerms>.\n<http://id.loc.gov/authorities/sh85076767#concept> <http://www.w3.org/2004/02/skos/core#prefLabel> "Lichen planus"@en.\n<http://id.loc.gov/authorities/sh85076767#concept> <http://www.w3.org/2002/07/owl#sameAs> <info:lc/authorities/sh85076767>.\n<http://id.loc.gov/authorities/sh85076767#concept> <http://purl.org/dc/terms/modified> "1994-08-22T15:46:41-04:00"^^<http://www.w3.org/2001/XMLSchema#dateTime>.\n<http://id.loc.gov/authorities/sh85076767#concept> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2004/02/skos/core#Concept>.\n" >> collection.to_ntriples etc.
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A simple Ruby DSL for creating and working with RDF graphs as regular Ruby objects
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