Erlang echo script

echo.erl

%%% Sends a message back & forth
%%% Author: Thom Nichols
%%%
%%% Remote server communication demo.
%%% Use start_listener/1 to register a listener on a remote or local node.
%%% use send/2 to send a messge to a node and listen for its response.

-module(echo).
-author('Thom Nichols').
-import(erlang).
-import(io).
-import(global).
-export([
		send/0, send/1, send/2, 
		reply/0, 
		start_listener/0, start_listener/1
	]).

send() ->
	send(node()).

send(Node) ->
	send(Node, erlang:localtime()).

%%% Send a message to the given node.
send(Node, Msg) ->
	io:format('Sending message "~w" to ~w...~n',[Msg,Node]),
	Envelope = {Msg,self()},
	if 
		Node /= node() -> global:send(echo, Envelope);
		true ->	{echo, Node} ! {Msg, self()}
	end,

	receive
		{echo, Node, Resp} ->
			io:format('Response from ~w: ~w~n',[Node,Resp]),
			ok;
		Other ->
			io:format('Unexpected response: ~p~n', [Other]),
			ok
		after 10000 ->
			io:format('Timeout waiting for response from ~w~n',[Node]),
			{error, timeout}
	end.

reply() ->
	receive
		{Msg, Pid} when is_pid(Pid) ->
			io:format('Sending response ~w to ~w...~n',[Msg,Pid]),
			Pid ! {echo,node(),Msg};
		Other ->
			io:format('Unexpected message: ~p~n', [Other]),
			ok
		after 10000 ->
%			io:fwrite('Timeout, retrying...~n',[]),
			reply()
	end.

%%% Create a listener process on this node
start_listener() ->
	start_listener(node()).

%%% Create a listener process on the given node.
%%% On a non-local node, global:register_name is used
%%% to globally-register a unique process name
start_listener(Node) ->
	Pid = spawn(Node, echo, reply, []),
	if
		Node /= node() -> 
			global:register_name(echo, Pid),
			io:format('registered global.~n');
		true -> register( echo, Pid )
	end,
	io:format('Listener running on ~w~n',[Node]),
	{ok, echo}.

gistfile2.txt