pthread_mutex_lock(&(data->adata.mutex));

    if(xsend(data->adata.socket, size, req, 0) != 0) {
      <handle error>
    }

    zmq_msg_init(&zreply);

    if(zmq_recv(data->adata.socket, &zreply, 0)  != 0) {
       <handle error>
    }
    else {
        <process response>
    }

    pthread_mutex_unlock(&(data->adata.mutex));

    return RLM_MODULE_OK;
}