OpenCart with my framework please help!

Hey there,
I am integrating OpenCart with my current framwork for an existing site. I want to take advantage of the logging in that OpenCart Provides.

What session variables can I check to see if a user is logged in?
Keep in mind that I want to do this from my framework

$this->session->data['customer_id'] = $customer_query->row['customer_id'];

amdev wrote:$this->session->data['customer_id'] = $customer_query->row['customer_id'];

So if I were to use the normal php session access. Would i do something like this? :
I am not doing this from within the opencart framework. So would this be appropriate?