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SPARQL Client for RDF.rb

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


  • Executes queries against any SPARQL 1.0-compatible endpoints over HTTP.
  • Provides a query builder DSL for ASK, SELECT, DESCRIBE and CONSTRUCT queries.
  • Supports tuple result sets in both XML and JSON formats, with JSON being the preferred default for content negotiation purposes.
  • Supports graph results in any RDF serialization format understood by RDF.rb.
  • Returns results using the RDF.rb object model.
  • Supports accessing endpoints as read-only RDF::Repository instances.


require 'sparql/client'

sparql ="")

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 =[:s, :p, :o]).offset(100).limit(10)

query.each_solution do |solution|
  puts solution.inspect

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

Executing an arbitrary textual SPARQL query string

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

puts result.inspect   #=> true or false


  • {SPARQL::Client}
    • {SPARQL::Client::Query}
    • {SPARQL::Client::Repository}



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

% [sudo] gem install sparql-client


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

% git clone git://

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

% wget

Mailing List




  • Do your best to adhere to the existing coding conventions and idioms.
  • Don't use hard tabs, and don't leave trailing whitespace on any line.
  • Do document every method you add using YARD annotations. Read the tutorial or just look at the existing code for examples.
  • Don't touch the .gemspec, VERSION or AUTHORS files. If you need to change them, do so on your private branch only.
  • Do feel free to add yourself to the CREDITS file and the corresponding list in the the README. Alphabetical order applies.
  • Do note that in order for us to merge any non-trivial changes (as a rule of thumb, additions larger than about 15 lines of code), we need an explicit public domain dedication on record from you.



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