Request-reply service in C

//
// Hello World server
// Connects REP socket to tcp://*:5560
// Expects "Hello" from client, replies with "World"
//
#include "zhelpers.h"

int main (void)
{
void *context = zmq_init (1);

// Socket to talk to clients
void *responder = zmq_socket (context, ZMQ_REP);
zmq_connect (responder, "tcp://localhost:5560");

while (1) {
// Wait for next request from client
char *string = s_recv (responder);
printf ("Received request: [%s]\n", string);
free (string);

// Do some 'work'
sleep (1);

// Send reply back to client
s_send (responder, "World");
}
// We never get here but clean up anyhow
zmq_close (responder);
zmq_term (context);
return 0;
}