socket.erl

-module(socket).

-export([start/0, start_socket/1]).

start() -> spawn_link(?MODULE, start_socket, [self()]).

start_socket(Pid) ->
    {ok, ListenSocket} = gen_tcp:listen(3555,
					[{active, true}, {reuseaddr, true}]),
    connection(ListenSocket, Pid).

loop(Socket, Pid, Datar) ->
    case gen_tcp:recv(Socket, 0, 5000) of
      {ok, Data} when Data =/= <<4>> ->
	  case string:find(Data, "_start_") of
	    nomatch ->
		case string:find(Data, "_end_") of
		  nomatch -> loop(Socket, Pid, [Datar, Data]);
		  _ ->
		      Final = [Datar, string:replace(Data, "_end_", "")],
		      io:format("~w ~n",
				[jsx:decode(erlang:list_to_binary(Final),
					    [return_maps])]),
		      loop(Socket, Pid, <<"">>)
		end;
	    _ ->
		NewData = string:replace(Data, "_start_", ""),
		case string:find(Data, "_end_") of
		  nomatch -> loop(Socket, Pid, [Datar, NewData]);
		  _ ->
				Final = string:replace(NewData,"_end_",""),
			       jsx:decode(Final),
		      io:format("~s ~n", [jsx:decode(Final, [return_maps])]),
		      loop(Socket, Pid, <<"">>)
		end
	  end;
      _ -> ok = Pid:close(Socket)
    end.

connection(ListenSocket, Pid) ->
    inet:setopts(ListenSocket, [{active, false}]),
    {ok, Socket} = gen_tcp:accept(ListenSocket),
    loop(Socket, Pid, <<"">>).

%% it should be noted that, for my case, the client have the "_start_" string at the beginning and the string "_end_" at the end of the sent data.