$this->response->addHeader($header);Add a new PHP header to be sent to the user’s browser.
$this->response->redirect($url);Redirect user to a certain URL, can be internal and external.
$this->response->setCompression($compression);Set the compression level.
$this->response->setOutput($output);Add data to the content to be sent to the user’s browser for display.
$this->response->compress($data, $level = 0);Compress files with the compression level set in the OpenCart admin area.
$this->response->output();Actually output the data.