Single Sign On

Dear all,

 Single sign on - I know its pretty old topic here. But I have got a lot of doubts. I'm new to php as well as Yii. 

 First let me explain what I have understood about single sign on. Please correct me if I'm wrong.

 1. Single Sign on is used to login to various application / subdomains of a domain.

 2. Single Sign uses cookies as references.

 3. Cookies should be shared across all the domains/sub domains for single sign on to work

So far I have gone through few posts here and have made few configurations as below

session' => array(

		'class' => 'CDbHttpSession',

		'connectionID' => 'db',

		'sessionTableName' => 'session_table',

		'cookieParams' => array('domain' => 'localhost.'),


For testing purpose I gave created to Yii applications located under localhost/xyz and localhost/login. My requirement is when I log in through localhost/login I should be log in to localhost/xyz

To achieve this do I need to make any changes to "UserIdentity" and if yes what are the changes do I need to make. Please guide me.