I am a new-by to ZeroMQ and make my way through the C++ hello-world example of the echo client-server pattern (Request-Reply). The server looks like:
//
// Hello World server in C++
// Binds REP socket to tcp://*:5555
// Expects "Hello" from client, replies with "World"
//
#include <zmq.hpp>
#include <string>
#include <iostream>
#include <unistd.h>
int main () {
// Prepare our context and socket
zmq::context_t context (1);
zmq::socket_t socket (context, ZMQ_REP);
socket.bind ("tcp://*:5555");
while (true) {
zmq::message_t request;
// Wait for next request from client
socket.recv (&request);
std::cout << "Received Hello" << std::endl;
// Do some 'work'
sleep (1);
// Send reply back to client
zmq::message_t reply (5);
memcpy ((void *) reply.data (), "World", 5);
socket.send (reply);
}
return 0;
}
Now my question: How can I access / read the real data that socket.recv() ? Trying:
std::cout << request << std::endl;
resulted in an error message:
error: no match for ‘operator<<’ in ‘std::operator<< [with _Traits =
std::char_traits<char>](((std::basic_ostream<char, std::char_traits<char> >&)
(& std::cout)), ((const char*)"Received Hello")) << request’
The same goes for the client side that is sending the message. I don't find a way to display the real message...
The hello world example goes only half way and outputs the hard-coded values:
std::cout << "Received Hello" << std::endl;
Printing the actual response can be done as follows:
zmq::message_t reply;
socket.recv (&reply);
std::string rpl = std::string(static_cast<char*>(reply.data()), reply.size());
std::cout << rpl << std::endl;
There are some other useful examples in zhelpers.hpp.
I found that the following does what I want:
zmq::message_t request (msglen);
memcpy ( (void *) request.data(), myMessage, msglen);
char * requestmsg = new char [msglen];
memcpy (requestmsg, request.data(), request.size());
requestsocket.send (request);
std::cout << "Sending " << requestmsg << std::endl;
where msglen is of type int and myMessage is const char * tyoe. In this way, the server receives a human readable message. Hope this is not against any zeromq rules...
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