erlang 实现与 c++ 通讯

网络通讯常用的有2种：文本通讯和二进制通讯。文章分别在两种方式上实现erlang与c++通讯。

一、erlang 与 c++ 行通讯

行通讯是一种文本通讯，格式如“cmd args\n”，比较简单，erlang接收数据也比较简单，可以设置参数 {packet, line} ，缺点是表示方式单一，很难表示结构数据。

1、erlang 代码（server.erl）：

-module(server).-export([start/0]).-define( PORT, 5678).%% 启动服务并接受客户端的连接start() ->  {ok, LSock} = gen_tcp:listen(?PORT, [binary, {packet, line},{active, false}]),  io:format("socket listen: ~p on ~p ~n",[LSock, ?PORT]),  accept(LSock).accept(LSock) ->  {ok, ASock} = gen_tcp:accept(LSock),  spawn(fun() -> server_loop(ASock) end),  accept(LSock).server_loop(ASock) ->  case gen_tcp:recv(ASock, 0) of    {ok, Data} ->      io:format("recv line data: ~p~n", [Data]),      gen_tcp:send(ASock, Data),      server_loop(ASock);    {error, _} ->      {ok, recv_error}    end.

2、c++ 代码（test.cpp）：

#include <winsock2.h>#include <iostream>#pragma comment(lib, "ws2_32.lib")int main(int argc, char* argv[]){WSADATA wsaData;WSAStartup( MAKEWORD( 2, 2 ), &wsaData ); SOCKET sc = WSASocket(AF_INET, SOCK_STREAM, 0, NULL, 0, NULL);SOCKADDR_IN addr;int len=sizeof(addr);addr.sin_family=AF_INET;addr.sin_addr.s_addr = inet_addr("127.0.0.1");addr.sin_port = htons(5678);connect(sc, (struct sockaddr *)&addr, len);char buff[1024];memset(buff, 0, 1024);char data[] = "aaaaaa\n";//发送数据printf("send data: %s \n", data);send(sc, data, sizeof(data), 0);//接收数据recv(sc, buff, 1024, 0);printf("recv data: %s \n", buff);closesocket(sc);WSACleanup();getchar();return 0;}

二、erlang 与 c++ 包体通讯

包体通讯是二进制通讯，目前主要有结构体，json，asn.1，protobuf等等，最简单还可以这样定义：2个字节cmd + 2个字节字符长度 + 字符内容。

下面以结构体包体通讯示例：

1、erlang代码（server.erl）：

-module(server).-export([start/0]).-define( UINT, 32/unsigned-little-integer).-define( INT, 32/signed-little-integer).-define( USHORT, 16/unsigned-little-integer).-define( SHORT, 16/signed-little-integer).-define( UBYTE, 8/unsigned-little-integer).-define( BYTE, 8/signed-little-integer).-define( PORT, 5678).%% 启动服务并接受客户端的连接start() ->  {ok, LSock} = gen_tcp:listen(?PORT, [binary, {packet, 0},{active, false}]),  io:format("socket listen: ~p on ~p ~n",[LSock, ?PORT]),  accept(LSock).accept(LSock) ->  {ok, ASock} = gen_tcp:accept(LSock),  spawn(fun() -> server_loop(ASock) end),  accept(LSock).server_loop(ASock) ->  case gen_tcp:recv(ASock, 0) of    {ok, <<Len:?USHORT,Cmd:?USHORT,Contain:4/binary-unit:8,_Rest/binary>> = A} ->      %% _Rest 匹配C++字符串后面的结束符/0      io:format("recv data: ~p ~p ~p~n", [Len, Cmd, Contain]),      gen_tcp:send(ASock, A),      server_loop(ASock);    {ok, Data} ->      io:format("recv unformated data: ~p~n", [Data]),      server_loop(ASock);    {error, _} ->      {ok, recv_error}    end.

2、c++ 代码（test.cpp）：

#include <winsock2.h>#include <iostream>#pragma comment(lib, "ws2_32.lib")struct data{unsigned short int len;unsigned short int cmd;char content[5] ;};int main(int argc, char* argv[]){WSADATA wsaData;WSAStartup( MAKEWORD( 2, 2 ), &wsaData ); SOCKET sc = WSASocket(AF_INET, SOCK_STREAM, 0, NULL, 0, NULL);SOCKADDR_IN addr;int len=sizeof(addr);addr.sin_family=AF_INET;addr.sin_addr.s_addr = inet_addr("127.0.0.1");addr.sin_port = htons(5678);connect(sc, (struct sockaddr *)&addr, len);char buff[1024];memset(buff, 0, 1024);struct data pdata = {4, 1001, "test"};//发送数据printf("send data: %d %d %s \n", pdata.len, pdata.cmd, pdata.content);send(sc, (char *)&pdata, sizeof(pdata), 0);//接收数据recv(sc, buff, 1024, 0);struct data * pdata_get = (struct data *) buff;printf("recv data: %d %s \n", pdata_get->cmd, pdata_get->content);closesocket(sc);WSACleanup();getchar();return 0;}