[zeromq-dev] epgm / pgm / auto discovery in C++ on Windows and VS2013

[James Chapman]

On 26 November 2014 at 23:30, Dorvin <dorvin at tlen.pl> wrote:
> I don't see subscription in your code. You have to subscribe to
> something before you receive any message. Also bear in mind bind and
> connect are not always interchangable and in general I would advice
> publisher side to bind.
>
> Jarek


Thanks Jarek

Taking on board your comments I've created a separate project in order
to try and get this mechanism working, it also has the benefit of
being compilable by anyone on the list.

I looked at the following example from the user guide:
http://zguide.zeromq.org/cpp:wuproxy and tried to implement a similar
example. Obviously I'm still doing something wrong because I get
exceptions thrown when trying to bind on the publisher and an
exception thrown when trying to connect on the subscriber.

If I change from epgm to tcp (see publishAddress / subscribeAddress
string) then the publisher sucessfully sends messages, but the
subscriber doesn't receives them.

I'm stumped.

Again, code below. Any help would be appreciated.

-------------------------------------------------------------------------------

#include <iostream>
#include <string>

#include "zmq.hpp"

std::string eth0IP = "192.168.0.15";

/**
* Publisher example
*/
int main()
{

    // Set up the connection
    zmq::context_t context(1);
    zmq::socket_t * socket = new zmq::socket_t(context, ZMQ_PUB);
    //std::string publishAddress = "epgm://" + eth0IP + ";239.192.1.1:5555";
    std::string publishAddress = "tcp://*:5555";
    socket->bind(publishAddress.c_str());
    //int linger = 0;
    //socket->setsockopt(ZMQ_LINGER, &linger, sizeof(linger));

    // Send the message
    while (1)
    {
        std::cout << "Sending Heartbeat Message" << std::endl;
        std::string szMessageData = "Foo";

        zmq::message_t zmqMsgOut(sizeof(szMessageData) + 1);
        memcpy((void *)zmqMsgOut.data(), szMessageData.c_str(),
sizeof(szMessageData));

        bool status = socket->send(zmqMsgOut);
        if (status) {
            std::cout << "Heartbeat Message Sent." << std::endl;
        }
        else {
            std::cerr << "Heartbeat Message NOT Sent." << std::endl;
        }

        Sleep(1000);
    }

    // Close and delete the socket
    socket->disconnect(publishAddress.c_str());
    socket->close();
    delete socket;

    return 0;
}

-------------------------------------------------------------------------------

#include <iostream>
#include <string>

#include "zmq.hpp"

std::string eth0IP = "192.168.0.15";

/**
* Subscriber example
*/
int main()
{
    zmq::context_t zmqContext(1);
    zmq::socket_t * pZmqSocket = new zmq::socket_t(zmqContext, ZMQ_SUB);
    //std::string subscribeAddress = "epgm://" + eth0IP + ";239.192.1.1:5555";
    std::string subscribeAddress = "tcp://localhost:5556";
    pZmqSocket->connect(subscribeAddress.c_str());
    pZmqSocket->setsockopt(ZMQ_SUBSCRIBE, "", 0);
    std::cout << "Heartbeat responder BOUND" << std::endl;
    while (1)
    {
        std::cout << ".";
        //pZmqSocket->connected();
        zmq::message_t * pZmqMsgIn = new zmq::message_t();

        bool success = pZmqSocket->recv(pZmqMsgIn);
        if (success) {
            std::cout << "======== MESSAGE RECEIVED =========" << std::endl;
        }
        else {
            std::cerr << "Error receiving message" << std::endl;
        }

        //std::string * szMessageData = static_cast<std::string
*>(pZmqMsgIn->data());

        delete pZmqMsgIn;
    }
    delete pZmqSocket;

    return 0;
}