If you recall from Chapter 2, Introduction to Sockets, we said that messages are prefix matched when using the publisher-subscriber pattern and we have showed a work-around to get what the subscriber really wants. This time, we visit the PUB-SUB sockets by enveloping messages with separate keys.
The following is the server code:
/*
PUB – SUB wrap messages.
server.c
*/
#include "czmq.h"
int main (int argc, char const *argv[]) {
zctx_t* context = zctx_new();
void* pub = zsocket_new(context, ZMQ_PUB);
zsocket_bind(pub, "tcp://*:4040");
printf("starting server
");
for(;;) {
zstr_sendm(pub, "Company1");
zstr_send(pub, "Company Message to be ignored.");
zstr_sendm(pub, "Company10");
zstr_send(pub, "Company message to receive.");
zclock_sleep(10);
}
zsocket_destroy(context, pub);
zctx_destroy(&context);
return 0;
}And the following is the client code:
/*
PUB – SUB envelop messages.
client.c
*/
#include "czmq.h"
int main (int argc, char const *argv[]) {
zctx_t* context = zctx_new();
void* request = zsocket_new(context, ZMQ_SUB);
printf("Starting client...
");
zsocket_connect(request, "tcp://localhost:4040");
zsocket_set_subscribe (request, "Company10");
for(;;) {
char* env = zstr_recv(request);
char* msg = zstr_recv(request);
printf("env: %s | %s
", env, msg);
if(!msg) break;
free(env);
free(msg);
zclock_sleep(1);
}
zsocket_destroy(context, request);
zctx_destroy(&context);
return 0;
}..................Content has been hidden....................
You can't read the all page of ebook, please click here login for view all page.