Spencerx/rack-linkeddata

Rack middleware for Linked Data content negotiation.

Linked Data Content Negotiation for Rack Applications

This is Rack middleware that provides Linked Data content negotiation for Rack applications. You can use Rack::LinkedData with any Ruby web framework based on Rack, including with Ruby on Rails 3.0 and with Sinatra.

• http://github.com/datagraph/rack-linkeddata

Features

• Implements HTTP content negotiation for RDF content types.
• Supports all RDF.rb-compatible serialization formats.
• Compatible with any Rack application and any Rack-based framework.

Examples

Adding Linked Data content negotiation to a Rails 3.x application

# config/application.rb
require 'rack/linkeddata'

class Application < Rails::Application
  config.middleware.use Rack::LinkedData::ContentNegotiation
end

Adding Linked Data content negotiation to a Sinatra application

#!/usr/bin/env ruby -rubygems
require 'sinatra'
require 'rack/linkeddata'

use Rack::LinkedData::ContentNegotiation

get '/hello' do
  RDF::Graph.new do |graph|
    graph << [RDF::Node.new, RDF::DC.title, "Hello, world!"]
  end
end

Adding Linked Data content negotiation to a Rackup application

#!/usr/bin/env rackup
require 'rack/linkeddata'

rdf = RDF::Graph.new do |graph|
  graph << [RDF::Node.new, RDF::DC.title, "Hello, world!"]
end

use Rack::LinkedData::ContentNegotiation
run lambda { |env| [200, {}, rdf] }

Defining a default Linked Data content type

use Rack::LinkedData::ContentNegotiation, :default => "text/turtle"

Testing Linked Data content negotiation using rackup and curl

$ rackup doc/examples/hello.ru

$ curl -iH "Accept: text/plain" http://localhost:9292/hello
$ curl -iH "Accept: text/turtle" http://localhost:9292/hello
$ curl -iH "Accept: application/rdf+xml" http://localhost:9292/hello
$ curl -iH "Accept: application/json" http://localhost:9292/hello
$ curl -iH "Accept: application/trix" http://localhost:9292/hello
$ curl -iH "Accept: */*" http://localhost:9292/hello

Description

Rack::LinkedData implements content negotiation for any Rack response object that implements the RDF::Enumerable mixin. You would typically return an instance of RDF::Graph or RDF::Repository from your Rack application, and let the Rack::LinkedData::ContentNegotiation middleware take care of serializing your response into whatever RDF format the HTTP client requested and understands.

The middleware queries RDF.rb for the MIME content types of known RDF serialization formats, so it will work with whatever serialization plugins that are currently available for RDF.rb. (At present, this includes support for N-Triples, Turtle, RDF/XML, RDF/JSON and TriX.)

Documentation

http://datagraph.rubyforge.org/rack-linkeddata/

• {Rack::LinkedData}
  • {Rack::LinkedData::ContentNegotiation}

Dependencies

• Rack (>= 1.0.0)
• Linked Data (>= 0.3.0)

Installation

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

% [sudo] gem install rack-linkeddata

Download

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

% git clone git://github.com/datagraph/rack-linkeddata.git

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

% wget http://github.com/datagraph/rack-linkeddata/tarball/master

References

• http://www.w3.org/DesignIssues/LinkedData.html
• http://linkeddata.org/docs/how-to-publish
• http://linkeddata.org/conneg-303-redirect-code-samples
• http://www.w3.org/TR/cooluris/
• http://www.w3.org/TR/swbp-vocab-pub/
• http://patterns.dataincubator.org/book/publishing-patterns.html

Authors

• Arto Bendiken - http://ar.to/

License

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