Convert $wp_session object to array

$wp_session = WP_Session::get_instance();
 is method to create your own  session in woocommerce/wordpress.
You can use $wp_session['session_name'] on any file in woocommerce/wordpress
after creating but if you want to change its value you need to first convert this object to array.

For creating array use
$temp = current((array)$wp_session['session_name']);

$temp return you the array / value assigned to $wp_session['session_name']...
Now use or edit $temp as your need and after use assign this array again to $wp_session['session_name']
using

unset ($wp_session['session_name']);
$wp_session['session_name']=$temp;
Example :
$wp_session = WP_Session::get_instance();
$temp = current((array)$wp_session['session_name']);
/***

Work with the array

***/
unset ($wp_session['session_name']);
$wp_session['session_name']=$temp;

Use $_SESSION in WordPress/Woocommerce

By default you cannot create your $_SESSION in WordPress/Woocommerce.
The information in $_SESSION remain in only those files on which it is created.
You cant access $_SESSION on  other file.

So, for creating your own session variable you need to install
WP Session Manager plugin.To download you can visit

http://wordpress.org/plugins/wp-session-manager/

And to use the $_SESSION you need to first create session object.
To create object use below line.

$wp_session = WP_Session::get_instance();

and to set value use

$wp_session['session_name']=array('one'=>'1','two'=>'2');
or
$wp_session['session_name']="Your value";

Note: You have to first create session object on every file where you wish to use $wp_session object.

Session variable in cakephp

PHP session  allows you to store user information on the server for later use (i.e. username, time,visited urls etc), this information is temporary and
will be deleted after the user has left the website.

To access session variable in cakephp... Go to controller in which you want to see session variable and add following two lines in code..

$session=$this->Session->read();
pr($session);