a number */ public function start($data, $metadata = [], $options = []) { $message_array = ['message' => $this->serializeMessage($data)]; if (isset($options['flags'])) { $message_array['flags'] = $options['flags']; } $event = $this->call->startBatch([ OP_SEND_INITIAL_METADATA => $metadata, OP_RECV_INITIAL_METADATA => true, OP_SEND_MESSAGE => $message_array, OP_SEND_CLOSE_FROM_CLIENT => true, ]); $this->metadata = $event->metadata; } /** * Wait for the server to respond with data and a status. * * @return array [response data, status] */ public function wait() { $event = $this->call->startBatch([ OP_RECV_MESSAGE => true, OP_RECV_STATUS_ON_CLIENT => true, ]); $status = $event->status; $this->trailing_metadata = $status->metadata; return [$this->deserializeResponse($event->message), $status]; } }