require 'uri'

class Message
  attr_accessor :from, :to, :body

  def initialize(from, to, body)
    @from = from
    @to = URI.parse(to)
    @body = body
  end
end

class MessageGateway
  def initialize
    load_adapters
  end

  def process_message(message)
    adapter = adapter_for(message)
    adapter.send_message(message)
  end

  def adapter_for(message)
    protocol = message.to.scheme
    adapter_class = protocol.capitalize + 'Adapter'
    adapter_class = self.class.const_get(adapter_class)
    adapter_class.new
  end

  def load_adapters
    lib_dir = File.dirname(__FILE__)
    full_pattern = File.join(lib_dir, 'adapter', '*.rb')
    Dir.glob(full_pattern).each {|file| require file }
  end
end

m = Message.new('from', 'ftp://xxxxx?ggg=2', 'bodybody')
mg = MessageGateway.new
mg.process_message(m)

$ ruby test.rb
"FtpAdapter:send_message #<Message:0x00007fe951195658>"