diff options
Diffstat (limited to 'lib/4store.rb')
-rw-r--r-- | lib/4store.rb | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/lib/4store.rb b/lib/4store.rb new file mode 100644 index 0000000..3ed081d --- /dev/null +++ b/lib/4store.rb @@ -0,0 +1,122 @@ +module OpenTox + module Backend + class FourStore + + @@accept_formats = [ "application/rdf+xml", "text/turtle", "text/plain", "text/uri-list", "text/html", 'application/sparql-results+xml' ] + @@content_type_formats = [ "application/rdf+xml", "text/turtle", "text/plain" ] + + def self.list mime_type + mime_type = "text/html" if mime_type.match(%r{\*/\*}) + bad_request_error "'#{mime_type}' is not a supported mime type. Please specify one of #{@@accept_formats.join(", ")} in the Accept Header." unless @@accept_formats.include? mime_type + if mime_type =~ /uri-list/ + sparql = "SELECT DISTINCT ?g WHERE {GRAPH ?g {?s <#{RDF.type}> <#{klass}>; ?p ?o. } }" + else + sparql = "CONSTRUCT {?s ?p ?o.} WHERE {?s <#{RDF.type}> <#{klass}>; ?p ?o. }" + end + query sparql, mime_type + end + + def self.get uri, mime_type + mime_type = "text/html" if mime_type.match(%r{\*/\*}) + bad_request_error "'#{mime_type}' is not a supported mime type. Please specify one of #{@@accept_formats.join(", ")} in the Accept Header." unless @@accept_formats.include? mime_type + sparql = "CONSTRUCT {?s ?p ?o.} FROM <#{uri}> WHERE { ?s ?p ?o. }" + rdf = query sparql, mime_type + resource_not_found_error "#{uri} not found." if rdf.empty? + rdf + end + + def self.post uri, rdf, mime_type + bad_request_error "'#{mime_type}' is not a supported content type. Please use one of #{@@content_type_formats.join(", ")}." unless @@content_type_formats.include? mime_type or mime_type == "multipart/form-data" + bad_request_error "Reqest body empty." unless rdf + mime_type = "application/x-turtle" if mime_type == "text/plain" # ntriples is turtle in 4store + begin + RestClient.post File.join(four_store_uri,"data")+"/", :data => rdf, :graph => uri, "mime-type" => mime_type + rescue + bad_request_error $!.message, File.join(four_store_uri,"data")+"/" + end + end + + def self.put uri, rdf, mime_type + bad_request_error "'#{mime_type}' is not a supported content type. Please use one of #{@@content_type_formats.join(", ")}." unless @@content_type_formats.include? mime_type + bad_request_error "Reqest body empty." unless rdf + mime_type = "application/x-turtle" if mime_type == "text/plain" + #begin + RestClientWrapper.put File.join(four_store_uri,"data",uri), rdf, :content_type => mime_type + #rescue + #bad_request_error $!.message, File.join(four_store_uri,"data",uri) + #end + end + + def self.delete uri + RestClientWrapper.delete data_uri(uri) + end + + def self.update sparql + RestClient.post(update_uri, :update => sparql ) + end + + def self.query sparql, mime_type + if sparql =~ /SELECT/i +# return list unless mime_type + case mime_type + when 'application/sparql-results+xml' + RestClient.get(sparql_uri, :params => { :query => sparql }, :accept => mime_type).body + when "text/uri-list" + RestClient.get(sparql_uri, :params => { :query => sparql }, :accept => "text/plain").body.gsub(/"|<|>/,'').split("\n").drop(1).join("\n") + else + bad_request_error "#{mime_type} is not a supported mime type for SELECT statements." + end + elsif sparql =~ /CONSTRUCT/i + case mime_type + when "text/plain", "application/rdf+xml" + RestClient.get(sparql_uri, :params => { :query => sparql }, :accept => mime_type).body + when /html|turtle/ + # TODO: fix and improve + nt = RestClient.get(sparql_uri, :params => { :query => sparql }, :accept => "text/plain").body # 4store returns ntriples for turtle + + rdf = RDF::Graph.new + RDF::Reader.for(:ntriples).new(nt) do |reader| + reader.each_statement { |statement| rdf << statement } + end + prefixes = {:rdf => "http://www.w3.org/1999/02/22-rdf-syntax-ns#type"} + ['OT', 'DC', 'XSD', 'OLO'].each{|p| prefixes[p.downcase.to_sym] = eval("RDF::#{p}.to_s") } + # TODO: fails for large datasets?? multi_cell_call + turtle = RDF::N3::Writer.for(:turtle).buffer(:prefixes => prefixes) do |writer| + rdf.each{|statement| writer << statement} + end + regex = Regexp.new '(https?:\/\/[\S]+)([>"])' + turtle = "<html><body>" + turtle.gsub( regex, '<a href="\1">\1</a>\2' ).gsub(/\n/,'<br/>') + "</body></html>" if mime_type =~ /html/ and !turtle.empty? + turtle + end + else + # TODO: check if this prevents SPARQL injections + bad_request_error "Only SELECT and CONSTRUCT are accepted SPARQL statements." + end + rescue + bad_request_error $!.message, sparql_uri + end + + def self.klass + RDF::OT[SERVICE.capitalize] + end + + def self.four_store_uri + # credentials are removed from uri in error.rb + $four_store[:uri].sub(%r{//},"//#{$four_store[:user]}:#{$four_store[:password]}@") + end + + def self.sparql_uri + File.join(four_store_uri, "sparql") + '/' + end + + def self.update_uri + File.join(four_store_uri, "update") + '/' + end + + def self.data_uri uri + File.join(four_store_uri, "data","?graph=#{uri}") + end + + end + end +end |