client.rb

require 'rubygems'
require 'eventmachine'

module TapsClient
  def post_init
    send_data("hey!")
  end

  def receive_data(data)
    p [Time.now, data]
    STDOUT.flush
  end
end

EventMachine.run do
  EM.connect 'localhost', 5678, TapsClient
end

server.rb

require 'rubygems'
require 'eventmachine'

module TapsServer

  def recieve_data(data)
    send_data(data)
  end

end

EM.run do
  EM.start_server('localhost', 5678, TapsServer)
end