universal-sub-test.c

/* This software is the client component of the ND-OV system.
 * Each multipart message it receives from the ND-OV system
 * consisting of an envelope and its data is rebroadcasted
 * to all connected clients of the serviceprovider.
 *
 * Requirements: zeromq2 or zeromq3.2
 * gcc -lzmq -o universal-sub-pubsub universal-sub-pubsub.c
 *
 * Changes:
 *  - Initial version <stefan@opengeo.nl>
 *  - zeromq 3.2 compatibility added,
 *    pubsub binding bugfix  <p.r.fokkinga@rug.nl>
 */

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <unistd.h>
#include "zmq.h"

int main (int argc, char *argv[]) {
    if (argc < 2) {
        printf("%s [subscriber] (filter1 filter2 filterN)\n\nEx.\n" \
                "%s tcp://127.0.0.1:7817\n",
                argv[0], argv[0]);
        exit(-1);
    }

    void *context  = zmq_init (1);

    zmq_pollitem_t items[1];

init:
    items[0].socket = zmq_socket (context, ZMQ_SUB);
    items[0].events = ZMQ_POLLIN;

    /* Apply filters to the subscription from the remote source */
    if (argc > 3) {
        unsigned int i;

        for (i = 2; i < argc; i++) {
            zmq_setsockopt (items[0].socket, ZMQ_SUBSCRIBE, argv[i], strlen(argv[i]));
        }
    } else {
        zmq_setsockopt (items[0].socket, ZMQ_SUBSCRIBE, "", 0);
    }

    zmq_connect (items[0].socket, argv[1]);

    int rc;
    size_t more_size = sizeof(more_t);

    /* Ensure that every 60s there is data */
    while ((rc = zmq_poll (items, 1, 10 * ZMQ_POLL_MSEC)) >= 0) {
        if (rc > 0) {
            more_t more;
            do {
                /* Create an empty 0MQ message to hold the message part */
                zmq_msg_t part;
                rc = zmq_msg_init (&part);
                assert (rc == 0);

                /* Block until a message is available to be received from the socket */
                rc = zmq_msg_recv (&part, items[0].socket, 0);
                assert (rc != -1);

                /* Determine if more message parts are to follow */
                rc = zmq_getsockopt (items[0].socket, ZMQ_RCVMORE, &more, &more_size);
                assert (rc == 0);

                zmq_msg_close (&part);
            } while (more);
        } else {
            zmq_close (items[0].socket);
            goto init;
        }
    }

    zmq_close (items[0].socket);

    zmq_ctx_destroy (context);

    return rc;
}