A simple erlang server demo.

bottles.erl

-module(bottles).
-export([start/0, start/1, server_loop/1, take/0, info/0, stop/0]).

start() ->
    start(99).

start(State) ->
    Pid = spawn(bottles, server_loop, [State]),
    pg2:create(bottles_server),
    pg2:join(bottles_server, Pid),
    Pid.

server_loop(State) ->
    NewState = receive
        {From, stop} ->
            From ! stopped,
            exit(normal);
        {From, info} ->
            From ! State,
            State;
        {From, take_one_down} ->
            From ! ok,
            State - 1
    end,
    bottles:server_loop(NewState).

take() ->
    pg2:get_closest_pid(bottles_server) ! {self(), take_one_down},
    receive X -> X end.

info() ->
    pg2:get_closest_pid(bottles_server) ! {self(), info},
    receive X -> X end.

stop() ->
    pg2:get_closest_pid(bottles_server) ! {self(), stop},
    stopped == receive X -> X end.