Artificial Intelligence Blog

Reuters has a great attitude about openly sharing data and technology. About 8 years ago, I obtained a free license for their 1.2 gigabytes of semantically tagged news corpus text - very useful for automated training of my KBtextmaster system as well as other work.

Reuters has done it again, releasing free access to OpenCalias semantic text processing web services. If you sign up for a free access key (good for 20,000 uses a day of their web services), then you can use my Ruby client library:

# Copyright Mark Watson 2008. All rights reserved.
# Can be used under either the Apache 2 or the LGPL licenses.

require 'simple_http'

require "rexml/document"
include REXML

require 'pp'

MY_KEY = ENV["OPEN_CALAIS_KEY"]
raise(StandardError,"Set Open Calais login key in ENV: 'OPEN_CALAIS_KEY'") if !MY_KEY

PARAMS = "¶msXML=" + CGI.escape('<c:params xmlns:c="http://s.opencalais.com/1/pred/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"><c:processingDirectives c:contentType="text/txt" c:outputFormat="xml/rdf"></c:processingDirectives><c:userDirectives c:allowDistribution="true" c:allowSearch="true" c:externalID="17cabs901" c:submitter="ABC"></c:userDirectives><c:externalMetadata></c:externalMetadata></c:params>')

class OpenCalaisTaggedText
  def initialize text=""
    data = "licenseID=#{MY_KEY}&content=" + CGI.escape(text)
    http = SimpleHttp.new "http://api.opencalais.com/enlighten/calais.asmx/Enlighten"
    @response = CGI.unescapeHTML(http.post(data+PARAMS))
  end
  def get_tags
    h = {}
    index1 = @response.index('terms of service.-->')
    index1 = @response.index('<!--', index1)
    index2 = @response.index('-->', index1)
    txt = @response[index1+4..index2-1]
    lines = txt.split("\n")
    lines.each {|line|
      index = line.index(":")
      h[line[0...index]] = line[index+1..-1].split(',').collect {|x| x.strip} if index
    }
    h
  end 
  def get_semantic_XML
    @response
  end
  def pp_semantic_XML
    Document.new(@response).write($stdout, 0)
  end
end

Notice that this code expects an environment variable to be set with your OpenCalais access key - you can just hardwire your key in this code if you want. Here is some sample use:

tt = OpenCalaisTaggedText.new("President George Bush and Tony Blair spoke to Congress")

pp "tags:", tt.get_tags
pp "Semantic XML:", tt.get_semantic_XML
puts "Semantic XML pretty printed:"
tt.pp_semantic_XML

The tags print as:

"tags:"
{"Organization"=>["Congress"],
 "Person"=>["George Bush", "Tony Blair"],
 "Relations"=>["PersonPolitical"]}

OpenCalais looks like a great service. I am planning on using their service for a technology demo, merging in some of my own semantic text processing tools. I might also use their service for training other machine learning based systems. Reuters will also offer a commercial version with guaranteed service, etc.

Labels: NLP, Ruby, semantic web