oauth = Koala::Facebook::OAuth.new(APP_ID, APP_CODE)
signed_request = oauth.parse_signed_request(params["signed_request"])

{
"algorithm"=>"HMAC-SHA256",
"issued_at"=>1303883452,
"user"=>
{
"country"=>"us",
"locale"=>"en_US"
},
"user_id"=>"100002364226618"
}

rg = RestGraph.new( :app_id => APP_ID, :secret => APP_SECRET)
parsed_request = rg.parse_signed_request!(params["signed_request"])

require 'sinatra'
require 'rest-graph'

app_id = '123'
secret = 'abc'
config = {:app_id => app_id,
          :secret => secret}

post '/' do
  rg = RestGraph.new(config)
  rg.parse_signed_request!(params['signed_request'])
  "#{rg.get('me').inspect.gsub('<', '<')}n"
end

run Sinatra::Application