sparql-client

SPARQL Client for RDF.rb

This is a Ruby implementation of a SPARQL client for RDF.rb.

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Features

Examples

Querying a remote SPARQL endpoint

require 'sparql/client'
sparql = SPARQL::Client.new("http://dbpedia.org/sparql")

Querying a remote SPARQL endpoint with a custom User-Agent

By default, SPARQL::Client adds a User-Agent field to requests, but applications may choose to provide their own, using the headers option:

require 'sparql/client'
sparql = SPARQL::Client.new("http://dbpedia.org/sparql", headers: {'User-Agent' => 'MyBotName'})

Querying a remote SPARQL endpoint with a specified default graph

require 'sparql/client'
sparql = SPARQL::Client.new("http://dbpedia.org/sparql", { graph: "http://dbpedia.org" })

Querying a RDF::Repository instance

require 'rdf/trig'
repository = RDF::Repository.load("http://example/dataset.trig")
sparql = SPARQL::Client.new(repository)

Executing a boolean query and outputting the result

# ASK WHERE { ?s ?p ?o }
result = sparql.ask.whether([:s, :p, :o]).true?
puts result.inspect   #=> true or false

Executing a tuple query and iterating over the returned solutions

# SELECT * WHERE { ?s ?p ?o } OFFSET 100 LIMIT 10
query = sparql.select.where([:s, :p, :o]).offset(100).limit(10)

query.each_solution do |solution|
  puts solution.inspect
end

Executing a graph query and iterating over the returned statements

# CONSTRUCT { ?s ?p ?o } WHERE { ?s ?p ?o } LIMIT 10
query = sparql.construct([:s, :p, :o]).where([:s, :p, :o]).limit(10)

query.each_statement do |statement|
  puts statement.inspect
end

Executing an arbitrary textual SPARQL query string

result = sparql.query("ASK WHERE { ?s ?p ?o }")

puts result.inspect   #=> true or false

Inserting data into a graph

# INSERT DATA { <http://example.org/jhacker> <http://xmlns.com/foaf/0.1/name> "J. Random Hacker" .}
data = RDF::Graph.new do |graph|
  graph << [RDF::URI('http://example.org/jhacker'), RDF::Vocab::FOAF.name, "J. Random Hacker"]
end
sparql.insert_data(data)

Deleting data from a graph

# DELETE DATA { <http://example.org/jhacker> <http://xmlns.com/foaf/0.1/name> "J. Random Hacker" .}
data = RDF::Graph.new do |graph|
  graph << [RDF::URI('http://example.org/jhacker'), RDF::Vocab::FOAF.name, "J. Random Hacker"]
end
sparql.delete_data(data)

Documentation

Dependencies

Installation

The recommended installation method is via RubyGems. To install the latest official release of the SPARQL::Client gem, do:

% [sudo] gem install sparql-client

Download

To get a local working copy of the development repository, do:

% git clone git://github.com/ruby-rdf/sparql-client.git

Alternatively, download the latest development version as a tarball as follows:

% wget https://github.com/ruby-rdf/sparql-client/tarball/master

Mailing List

Authors

Contributors

Contributing

This repository uses Git Flow to mange development and release activity. All submissions must be on a feature branch based on the develop branch to ease staging and integration.

Resources

License

This is free and unencumbered public domain software. For more information, see https://unlicense.org/ or the accompanying {file:UNLICENSE} file.