#SPARQL Client for RDF.rb

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

• http://ruby-rdf.github.com/sparql-client/

##Features

• Executes queries against any SPARQL 1.0/1.1-compatible endpoint over HTTP, or against an RDF::Queryable instance, using the SPARQL gem.
• Provides a query builder DSL for ASK, SELECT, DESCRIBE and CONSTRUCT queries.
• Includes preliminary support for some SPARQL 1.1 Update operations.
• Supports tuple result sets in both XML, JSON, CSV and TSV 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

Querying a remote SPARQL endpoint

require 'sparql/client'

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

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

##Documentation

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

##Dependencies

• Ruby (>= 1.8.7) or (>= 1.8.1 with Backports)
• RDF.rb (>= 1.0)
• Net::HTTP::Persistent (>= 1.4)
• JSON (>= 1.4)
• Soft dependency on SPARQL (>= 1.0)

##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/ruby-rdf/sparql-client.git

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

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

##Mailing List

• http://lists.w3.org/Archives/Public/public-rdf-ruby/

##Authors

• Arto Bendiken - http://ar.to/
• Ben Lavender - http://bhuga.net/
• Gregg Kellogg - http://kellogg-assoc.com/

##Contributors

• Christoph Badura - http://github.com/b4d
• James Hetherington - http://twitter.com/jamespjh
• 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/
• Michael Sokol - http://sokolmichael.com/
• Yves Raimond - http://moustaki.org/
• Thomas Feron - http://github.com/thoferon

##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://ruby-rdf.github.com/sparql-client/
• http://github.com/ruby-rdf/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.