a snipept for something

duplex.rb

require 'em-proxy'

Proxy.start(host: "127.0.0.1", port: 8000, debug: false) do |conn|
  conn.server :server1, host: "127.0.0.1", port: 3000
  conn.server :server2, host: "127.0.0.1", port: 3001

  conn.on_data do |data|
    data
  end

  conn.on_response do |server, resp|
    if resp.include?("HTTP/1.1 200")
      @name = server
      resp
    end
  end

  conn.on_finish do |name|
    :close if @name == name
  end
end