Detailed explanation of ERLANG and PYTHON interworking implementation process

Recently, Erlang was developed, and its string processing ability was extremely speechless, so I decided to combine it with python to create a powerful distributed system. When system-level development is needed in the future, I will combine C++/C.

First of all, I refer to the official documents of Erlang and http://blog.developers.api.sina.com.cn/? tag=erlang and http://kazmier.net/computer/port-howto/.

After studying for nearly 24 hours, the problem was finally solved completely. Named town, town means market in English, which means the communication and interaction of various languages here. ))

-module(town).
-behaviour(gen_server).
 
%% API
-export([start/0,combine/1]).
 
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
-record(state, {port}).
 
start() ->
 gen_server:start_link({global, ?MODULE}, ?MODULE, [], []).
stop() ->
 gen_server:cast(?SERVER, stop).
init([]) ->
 process_flag(trap_exit, true),
 Port = open_port({spawn, "python -u /home/freefis/Desktop/town.py"},[stream,{line, 1024}]),
 {ok, #state{port = Port}}.
 
handle_call({combine,String}, _From, #state{port = Port} = State) ->
 port_command(Port,String),
 receive
 {Port,{data,{_Flag,Data}}} ->
  io:format("receiving:~p~n",[Data]),
  sleep(2000),
  {reply, Data, Port}
 end.
handle_cast(stop, State) ->
 {stop, normal, State};
handle_cast(_Msg, State) ->
 {noreply, State}.
 
handle_info(Info, State) ->
 {noreply,State}.
 
terminate(_Reason, Port) ->
 ok.
 
code_change(_OldVsn, State, _Extra) ->
 {ok, State}.
 
%%--------------------------------------------------------------------
%%% Internal ---------------------------------------------------------
combine(_String) ->
 start(),
 String = list_to_binary("combine|"++_String++"\n"),
 gen_server:call(?SERVER,{combine,String},infinity),
 stop().

This is the script of Python. When town: combine ("sentence1+sentence2") in erlang is executed, the script of python will be started in the background, and the result will be returned to Erlang after processing: sentence1sentence2, and then exit.

import sys
def handle(_string):
 if _string.startswith("combine|"):
  string = "".join( _string[8:].split(","))
  return string
 
"""waiting for input """
while 1:
 # Recv. Binary Stream as Standard IN
 _stream = sys.stdin.readline()
 
if not _stream: break
 # Scheme, Turn into Formal String
 inString = _stream.strip("\r\n")
 # handle String
 outString = handle(inString)
 # send to port as Standart OUT
 sys.stdout.write("%s\n" % (outString,))
 sys.exit(0)