最も簡単なErlang Socketプログラム

server.erl:

-module(server).
-export([start/0]).

start() ->
    {ok,Listen}=gen_tcp:listen(2345,[binary,{packet,4},
                                            {reuseaddr,true},
                                            {active,true}]),
    {ok,Socket}=gen_tcp:accept(Listen),
    gen_tcp:close(Listen),
    loop(Socket).

loop(Socket) ->
    receive
        {tcp,Socket,Bin} ->
            io:format("Server received binary = ~p~n",[Bin]),
            Str=binary_to_term(Bin),
            io:format("Server (unpacked) ~p~n",[Str]),
            Reply= Str ++ "** MLGB!",
            io:format("Server replying = ~p~n",[Reply]),
            gen_tcp:send(Socket,term_to_binary(Reply)),
            loop(Socket);
        {tcp_closed,Socket} ->
            io:format("Server socket closed~n")
    end.

client.erl:

-module(client).
-export([start/1]).

start(Str) ->
  {ok, Socket} = 
    gen_tcp:connect("localhost", 2345, [binary, {packet, 4}]),
    ok = gen_tcp:send(Socket, term_to_binary(Str)),
    receive
      {tcp, Socket, Bin} ->
        io:format("Client received binary = ~p~n", [Bin]),
        Val = binary_to_term(Bin),
        io:format("Client result = ~p~n", [Val]),
        gen_tcp:close(Socket)
    end.

コンパイル:

Eshell > c(server).
Eshell > c(client).

サーバを起動するには:

Eshell > server:start().

クライアントを起動するには:

Eshell > client:start("sb").

サーバ側出力:

Server received binary = <<131,107,0,2,115,98>>
Server (unpacked) "sb"
Server replying = "sb** MLGB!"
Server socket closed

クライアント側出力:

Client received binary = <<131,107,0,10,115,98,42,42,32,77,76,71,66,33>>
Client result = "sb** MLGB!"