[nanomsg] publish/subscribe keys
- From: "John Carneiro" <johncarneiro@xxxxxxxxxxx>
- To: <nanomsg@xxxxxxxxxxxxx>
- Date: Wed, 13 Aug 2014 16:47:57 -0400
Hello,
Described in this document is a simple pub/sub example, however neither
it nor the nanomsg documentation describes how to use publish/subscribe keys
or if they exist:
http://tim.dysinger.net/posts/2013-09-16-getting-started-with-nanomsg.html
It seems like this line from the example:
nn_setsockopt (sock, NN_SUB, NN_SUB_SUBSCRIBE, "", 0)
could easily be instead something like this to subscribe to a subscription
type of "sub1":
const char* subType = "sub1";
nn_setsockopt (sock, NN_SUB, NN_SUB_SUBSCRIBE, subType, strlen(subType) + 1)
and I would assume you could read this string on the publishing server like
this
char subType[100];
getsockopt(sock, NN_SOL_SOCKET, NN_PROTOCOL, &subType, sizeof(subType));
See below code modified from the original example to get my general
direction.
Is this the intent of pub/sub ?
If so, are there API calls that I'm missing or done incorrectly?
If not, what protocol or method would be better ?
Thanks
-
#include <assert.h>
#include <stdio.h>
#include "../src/nn.h"
#include "../src/pubsub.h"
#include "string.h"
#define SERVER "server"
#define CLIENT "client"
char *date ()
{
time_t raw = time (&raw);
struct tm *info = localtime (&raw);
char *text = asctime (info);
text[strlen(text)-1] = '\0'; // remove '\n'
return text;
}
int server (const char *url)
{
int sock = nn_socket (AF_SP, NN_PUB);
assert (sock >= 0);
assert (nn_bind (sock, url) >= 0);
char subType[100];
getsockopt(sock, NN_SOL_SOCKET, NN_PROTOCOL, &subType,
sizeof(subType));
if (strcmp(subType, "sub1") == 0)
{
while (1)
{
char *d = date();
int sz_d = strlen(d) + 1; // '\0' too
printf ("SERVER: PUBLISHING DATE %s\n", d);
int bytes = nn_send (sock, d, sz_d, 0);
assert (bytes == sz_d);
sleep(1);
}
}
else if (strcmp(subType, "sub2") == 0)
{
while (1)
{
const char *test = "test123";
int sz_test = strlen(test) + 1; // '\0' too
int bytes = nn_send (sock, test, sz_test, 0);
assert (bytes == sz_test);
sleep(1);
}
}
return nn_shutdown (sock, 0);
}
int client (const char *url, const char *name)
{
int sock = nn_socket (AF_SP, NN_SUB);
assert (sock >= 0);
const char* subType = "sub1";
assert (nn_setsockopt (sock, NN_SUB, NN_SUB_SUBSCRIBE, subType,
strlen(subType) + 1) >= 0);
assert (nn_connect (sock, url) >= 0);
while (1)
{
char *buf = NULL;
int bytes = nn_recv (sock, &buf, NN_MSG, 0);
assert (bytes >= 0);
printf ("CLIENT (%s): RECEIVED %s\n", name, buf);
nn_freemsg (buf);
}
return nn_shutdown (sock, 0);
}
int main (const int argc, const char **argv)
{
if (strncmp (SERVER, argv[1], strlen (SERVER)) == 0 && argc >= 2)
return server (argv[2]);
else if (strncmp (CLIENT, argv[1], strlen (CLIENT)) == 0 && argc >=
3)
return client (argv[2], argv[3]);
else
{
fprintf (stderr, "Usage: pubsub %s|%s <URL> <ARG> ...\n",
SERVER, CLIENT);
return 1;
}
}
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