#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include <nng/nng.h>
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#include <nng/protocol/pubsub0/pub.h>
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#include <nng/protocol/pubsub0/sub.h>
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#define SERVER "server"
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#define CLIENT "client"
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void
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fatal(const char *func, int rv)
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{
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fprintf(stderr, "%s: %s\n", func, nng_strerror(rv));
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}
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char *
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date(void)
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{
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time_t now = time(&now);
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struct tm *info = localtime(&now);
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char *text = asctime(info);
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text[strlen(text)-1] = '\0'; // remove '\n'
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return (text);
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}
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int
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server(const char *url)
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{
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nng_socket sock;
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int rv;
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char buf[1024];
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if ((rv = nng_pub0_open(&sock)) != 0) {
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fatal("nng_pub0_open", rv);
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}
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if ((rv = nng_listen(sock, url, NULL, 0)) < 0) {
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fatal("nng_listen", rv);
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}
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for (;;) {
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char *d = date();
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snprintf(buf, 1024, "time:%s", d);
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printf("SERVER: PUBLISHING DATE %s\n", d);
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if ((rv = nng_send(sock, buf, strlen(buf) + 1, 0)) != 0) {
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fatal("nng_send", rv);
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}
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sleep(1);
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}
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}
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int
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client(const char *url, const char *name)
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{
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nng_socket sock;
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int rv;
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if ((rv = nng_sub0_open(&sock)) != 0) {
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fatal("nng_sub0_open", rv);
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}
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// subscribe to everything (empty means all topics)
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if ((rv = nng_setopt(sock, NNG_OPT_SUB_SUBSCRIBE, "nnnnnnnnn", 0)) != 0) {
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fatal("nng_setopt", rv);
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}
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if ((rv = nng_dial(sock, url, NULL, 0)) != 0) {
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fatal("nng_dial", rv);
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}
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for (;;) {
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char *buf = NULL;
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size_t sz;
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if ((rv = nng_recv(sock, &buf, &sz, NNG_FLAG_ALLOC)) != 0) {
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fatal("nng_recv", rv);
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}
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printf("CLIENT (%s): RECEIVED %s\n", name, buf);
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nng_free(buf, sz);
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}
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}
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int
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main(const int argc, const char **argv)
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{
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if ((argc >= 2) && (strcmp(SERVER, argv[1]) == 0))
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return (server(argv[2]));
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if ((argc >= 3) && (strcmp(CLIENT, argv[1]) == 0))
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return (client (argv[2], argv[3]));
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fprintf(stderr, "Usage: pubsub %s|%s <URL> <ARG> ...\n",
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SERVER, CLIENT);
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return 1;
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}
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