echo_server.erl

-module(echo_server).

-compile(export_all).

%%% === Public API
start_link() ->
  spawn_link(fun() -> ok = init(), loop() end).

echo(Node, Message) ->
  echo(Node, Message, 5000).

echo(Node, Message, Timeout) ->
  {?MODULE, Node} ! {'echo$', self(), Message},
  receive
    {'echo$response', Message} ->
       ok
  after Timeout ->
    timeout
  end.

%%% === Internal API

init() ->
  register(?MODULE, self()),
  ok.

loop() ->
  receive
    {'echo$', From, Message} ->
      From ! {'echo$response', Message},
      loop();
    'echo$exit' ->
      ok
  end.