public function send()
{
if ($this->isSent) {
return;
}
$this->trigger(self::EVENT_BEFORE_SEND);
$this->prepare();
$this->trigger(self::EVENT_AFTER_PREPARE);
$this->sendHeaders();
$this->sendContent();
$this->trigger(self::EVENT_AFTER_SEND);
$this->isSent = true;
}