static void test_dealer(void* const context)
{   
    void* const dealer = zmq_socket(context, ZMQ_DEALER);
    //
    int rc = zmq_setsockopt(dealer, ZMQ_ROUTING_ID, "X", 1);
    assert(0 == rc);
    rc = zmq_connect(dealer, "inproc://a");
    assert(0 == rc);
    //
    ::std::this_thread::sleep_for(::std::chrono::seconds(5));
    zmq_close(dealer);
    //
    printf("close dealer\n");
}
int main(void)
{
    void* const context = zmq_ctx_new();
    //  
    void* const router = zmq_socket(context, ZMQ_ROUTER);
    //  
    const int on = 1;
    int rc = zmq_setsockopt(router, ZMQ_ROUTER_MANDATORY, &on, sizeof(on));
    assert(0 == rc);
    //  
    rc = zmq_bind(router, "inproc://a");
    assert(0 == rc);
    //  
    ::std::thread thread0(test_dealer, context);
    thread0.detach();
    ::std::this_thread::sleep_for(::std::chrono::seconds(1));
    //  
    while (1) {
        rc = zmq_send(router, "X", 1, ZMQ_SNDMORE);
        if (1 != rc) {
            break;
        }
        rc = zmq_send(router, "hello", 5, 0);
        if (5 != rc) {
            break;
        }
    }
    return 0;
}