SPARQL Client for RDF.rb

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

• http://github.com/bendiken/sparql-client

Features

• 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.

Examples

require 'sparql/client'

sparql = SPARQL::Client.new("http://dbpedia.org/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 = 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

Documentation

http://sparql.rubyforge.org/client/

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

Dependencies

• Ruby (>= 1.8.7) or (>= 1.8.1 with Backports)
• RDF.rb (>= 0.2.0)
• JSON (>= 1.4.0)

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/bendiken/sparql-client.git

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

% wget http://github.com/bendiken/sparql-client/tarball/master

Authors

• Arto Bendiken - http://ar.to/
• Ben Lavender - http://bhuga.net/

Contributors

• Gabriel Horner - http://tagaholic.me/
• Nicholas Humfrey - http://www.aelius.com/njh/
• Fumihiro Kato - http://fumi.me/
• David Nielsen - http://github.com/drankard
• Thamaraiselvan Poomalai - http://softonaut.blogspot.com/

Contributing

• 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.

Resources

• http://sparql.rubyforge.org/client/
• http://github.com/bendiken/sparql-client
• http://rubygems.org/gems/sparql-client
• http://rubyforge.org/projects/sparql/
• http://raa.ruby-lang.org/project/sparql-client/
• http://www.ohloh.net/p/rdf

License

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