facebook_cookieless_session_middleware.rb

require 'rack/utils'

class FacebookCookielessSessionMiddleware
  def initialize(app, session_key = '_session_id')
    @app = app
    @session_key = session_key
  end
  
  def call(env)
    params = Rack::Request.new(env)
    
    unless params[@session_key].nil?
      env[ENV_SESSION_OPTIONS_KEY].merge({:id => params[@session_key]})
    end
    
    @app.call(env)
  end
end