[UPHPU] sessions in front controller

[jtaber]

having mental blockage on this one:
a front controller has a session_start() to initialize the session but 
each time a page is called the session_start()  gets called again which 
seems to wipe out the session vars - tried to wrap the session_start() ie

if (!isset($_SESSION['start'])) {
session_start();
$_SESSION['start']=1;
}
.... test for right session
.....

is this right ?  does anyone have an example of using session in a front 
controller (sorry google search wasn't showing me any good examples).  thks