public function __construct($sender_id, $sub_addr, $pub_addr)
{
$this->sender_id = $sender_id;
$ctx = new \ZMQContext();
$reqs = $ctx->getSocket(\ZMQ::SOCKET_UPSTREAM);
$reqs->connect($sub_addr);
$resp = $ctx->getSocket(\ZMQ::SOCKET_PUB);
$resp->connect($pub_addr);
$resp->setSockOpt(\ZMQ::SOCKOPT_IDENTITY, $sender_id);
$this->sub_addr = $sub_addr;
$this->pub_addr = $pub_addr;
$this->reqs = $reqs;
$this->resp = $resp;
}