Bitcoin JSON-RPC sample fails to connect to monacoind (?) https://en.bitcoin.it/wiki/API_reference_%28JSON-RPC%29#Ruby

monacoin_rpc.rb

require 'net/http'
require 'uri'
require 'json'

class BitcoinRPC
  def initialize(service_url)
    @uri = URI.parse(service_url)
  end

  def method_missing(name, *args)
    post_body = { 'method' => name, 'params' => args, 'id' => 'jsonrpc' }.to_json
    resp = JSON.parse( http_post_request(post_body) )
    raise JSONRPCError, resp['error'] if resp['error']
    resp['result']
  end

  def http_post_request(post_body)
    http = Net::HTTP.new(@uri.host, @uri.port)
    http.use_ssl = false
    request = Net::HTTP::Post.new(@uri.request_uri)
    request.basic_auth( @uri.user, @uri.password)
    request.content_type = 'application/json'
    request.body = post_body
    http.request(request).body
  end

  class JSONRPCError < RuntimeError; end
end

if $0 == __FILE__
  h = BitcoinRPC.new('http://monacoinrpc:DytCKSu2kwwbgWAFQqhV7rEb3KxoT6d31Z7DThpEjt2F@127.0.0.1:9401')
  p h.getbalance
  p h.getinfo
  # also see: https://en.bitcoin.it/wiki/Original_Bitcoin_client/API_Calls_list
end

result

/home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/protocol.rb:153:in `read_nonblock': end of file reached (EOFError)
        from /home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/protocol.rb:153:in `rbuf_fill'
        from /home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/protocol.rb:134:in `readuntil'
        from /home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/protocol.rb:144:in `readline'
        from /home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/http/response.rb:39:in `read_status_line'
        from /home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/http/response.rb:28:in `read_new'
        from /home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/http.rb:1406:in `block in transport_request'
        from /home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/http.rb:1403:in `catch'
        from /home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/http.rb:1403:in `transport_request'
        from /home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/http.rb:1376:in `request'
        from /home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/http.rb:1369:in `block in request'
        from /home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/http.rb:852:in `start'
        from /home/osyoyu/.rbenv/versions/2.0.0-p353/lib/ruby/2.0.0/net/http.rb:1367:in `request'
        from monacoin_rpc_orig.rb:24:in `http_post_request'
        from monacoin_rpc_orig.rb:12:in `method_missing'
        from monacoin_rpc_orig.rb:32:in `<main>'