005 ZeroMQ REQ--REP代理應答與請求

框架：
優點是，如果客戶端是同型的，服務端也是同型的，都可以動態加入或退出。
但消息只實現一半路由，要完全路由，參考上一篇文章。

內部消息傳遞原理：

實現代碼：
client.cpp:

#include<zmq.h>
#include<iostream>
#include<thread>
#include<chrono>
using std::endl;
using std::cout;

int main()
{
    void* pContext = zmq_ctx_new();
    void* pReqSock = zmq_socket(pContext, ZMQ_REQ);
    zmq_connect(pReqSock, "tcp://localhost:6601");
    cout << "start client..." << endl;
    while (true)
    {
        static int i = 0;
        cout << "sent hello:" << i;
        zmq_msg_t msgOut;
        zmq_msg_init_size(&msgOut,16);
        sprintf_s((char*)zmq_msg_data(&msgOut), 16, "hello%d", i++);
        zmq_msg_send(&msgOut, pReqSock, 0);
        zmq_msg_close(&msgOut);

        zmq_msg_t msgIn;
        zmq_msg_init(&msgIn);
        zmq_msg_recv(&msgIn, pReqSock, 0);
        cout << "----------receive:" << (char*)zmq_msg_data(&msgIn)<<endl;
        zmq_msg_close(&msgIn);

        std::this_thread::sleep_for(std::chrono::milliseconds(200));
    }
    zmq_close(pReqSock);
    zmq_ctx_destroy(pContext);
    return 0;
}

proxy.cpp

#include<zmq.h>
#include<iostream>
using std::endl;
using std::cout;

int main()
{
    void* pContext = zmq_ctx_new();
    void* frontEnd = zmq_socket(pContext, ZMQ_ROUTER);
    zmq_bind(frontEnd, "tcp://*:6601");

    void* backEnd = zmq_socket(pContext, ZMQ_DEALER);
    zmq_bind(backEnd, "tcp://*:6602");

    cout << "start proxy..." << endl;
    zmq_proxy(frontEnd, backEnd, NULL);//爲了省事就直接使用內置代理了，這裏也可以手動實現zmq_poll,zmq_pollitem_t,參考前一篇手動實現代理過程，比較複雜。

    zmq_close(frontEnd);
    zmq_close(backEnd);
    zmq_ctx_destroy(pContext);
    return 0;
}

server.cpp

#include<zmq.h>
#include<iostream>
using std::endl;
using std::cout;

int main()
{
    void* pContext = zmq_ctx_new();
    void* pReqSock = zmq_socket(pContext, ZMQ_REP);
    zmq_connect(pReqSock, "tcp://localhost:6602");
    cout << "start server..." << endl;
    while (true)
    {

        zmq_msg_t msgIn;
        zmq_msg_init(&msgIn);
        zmq_msg_recv(&msgIn, pReqSock, 0);
        cout << "get:" << (char*)zmq_msg_data(&msgIn);
        zmq_msg_close(&msgIn);

        static int i = 0;
        cout << "-----reply world:" << i<<endl;
        zmq_msg_t msgOut;
        zmq_msg_init_size(&msgOut, 16);
        sprintf_s((char*)zmq_msg_data(&msgOut), 16, "world%d", i++);
        zmq_msg_send(&msgOut, pReqSock, 0);
        zmq_msg_close(&msgOut);

    }
    zmq_close(pReqSock);
    zmq_ctx_destroy(pContext);
    return 0;
}