A ZMQ PUB SUB example

ZMQ PUB SUB

Makefile

all:
	g++ pub.cpp `pkg-config --cflags --libs libzmq` -o pub
	g++ sub.cpp `pkg-config --cflags --libs libzmq` -o sub
clean:
	rm pub sub

pub.cpp

#include <zmq.hpp>
#include <iostream>

using namespace std;

static const string PUBLISH_ENDPOINT = "tcp://127.0.0.1:4321";

int main (int argc, char *argv[]) {
    // Create a publisher socket
    zmq::context_t context;
    zmq::socket_t socket (context, zmq::socket_type::pub);
    // Open the connection
    socket.bind (PUBLISH_ENDPOINT);

    while(true) {
        string text = "Hello";
        // Create a message and feed data into it
        zmq::message_t message(text.size());
        memcpy (message.data (), text.data (), text.size ());
        socket.send(message, zmq::send_flags::dontwait);
    }

    // Unreachable, but for good measure
    socket.disconnect (PUBLISH_ENDPOINT);
    return 0;
}

sub.cpp

#include <zmq.hpp>
#include <iostream>

using namespace std;

static const string PUBLISHER_ENDPOINT = "tcp://localhost:4321";

int main (int argc, char *argv[]) {
    // Create a subscriber socket
    zmq::context_t context;
    zmq::socket_t socket (context, zmq::socket_type::sub);
    // Subscribe to all messages
    socket.setsockopt(ZMQ_SUBSCRIBE, "", 0);
    // Connect to the publisher
    socket.connect(PUBLISHER_ENDPOINT);

    while(true) {
        zmq::message_t message;
        socket.recv (message, zmq::recv_flags::dontwait);
        // Read as a string
        string text = std::string (static_cast<char*>(message.data ()), message.size ());
        if (!text.empty())
            cout << "[RECV] #" << ": \"" << text << "\"" << endl;
    }

    // Unreachable, but for good measure
    socket.disconnect (PUBLISHER_ENDPOINT);
    return 0;
}