inproc & dealer socket error

inproc_dealer.c

#include "zmq.h"

#include <stdio.h>
#include <string.h>
#include <unistd.h>

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

    void *a = zmq_socket (context, ZMQ_DEALER);
    void *b = zmq_socket (context, ZMQ_DEALER);

    const char *address = "inproc://foo";

    zmq_bind (a, address);
    sleep (1);
    zmq_connect (b, address);
    sleep (1);

    /* s_send (a, "foo"); */
    zmq_msg_t out_message;
    zmq_msg_init_size (&out_message, 3);
    memcpy (zmq_msg_data(&out_message), "foo", 3);
    int rc = zmq_send (a, &out_message, 0);
    zmq_msg_close (&out_message);

    printf ("out rc = %d\n", rc);

    /* char *string = s_recv (b); */
    zmq_msg_t in_message;
    zmq_msg_init (&in_message);
    rc = zmq_recv (b, &in_message, 0);
    printf("in rc = %d\n", rc);

    int size = zmq_msg_size (&in_message);
    char *string = malloc (size + 1);
    memcpy (string, zmq_msg_data (&in_message), size);
    zmq_msg_close (&in_message);
    string[size] = '\0';
    printf ("%s\n", string);

    zmq_close (a);
    zmq_close (b);
    zmq_term (context);
    return 0;
}

inproc_dealer_fail.js

// var address = 'tcp://127.0.0.1:5555';
var address = 'inproc://foo';
var zmq = require('zmq');

var a = zmq.socket('dealer')
  , b = zmq.socket('dealer');

b.on('message', function(data) {
  console.log(data.toString()); // This should print 'foo' but is never called
});

a.bind(address, function() {
  setTimeout(function() {
    b.connect(address);

    setTimeout(function() {
      a.send('foo');
    }, 1000);
  }, 1000);
});

You C application and the node application don't run in the same process. Therefor you cannot have in-process communication

@Tristramg, I'm not sure what you mean by that. inproc refers to intra-process, and both codes run in one process respectively, hence they should work.