$uniacid :
$openid :
$expire :
$session_name :
start( $uniacid, $openid, $expire = 3600)
setHandler( $type = 'mysql')
open( $save_path, $session_name)
close()
read( $sessionid)
write( $sessionid, $data)
destroy( $sessionid)
gc( $expire)
key( $sessionid)