# File lib/fog/atmos/models/storage/file.rb, line 59
        def public_url(expires = (Time.now + 5 * 365 * 24 * 60 * 60))
          requires :objectid
          # TODO - more efficient method to get this?
          storage = Fog::Storage.new(:provider => 'Atmos')
          uri = URI::HTTP.build(:scheme => @prefix, :host => @storage_host, :port => @storage_port.to_i, :path => "/rest/objects/#{objectid}" )
          Fog::Storage.new(:provider => 'Atmos').uid

          sb = "GET\n"
          sb += uri.path.downcase + "\n"
          sb += storage.uid + "\n"
          sb += String(expires.to_i())

          signature = storage.sign( sb )
          uri.query = "uid=#{CGI::escape(storage.uid)}&expires=#{expires.to_i()}&signature=#{CGI::escape(signature)}"
          uri.to_s
        end