How can we achieve Login/Logout/Registration Functionality in a Tridion based website ?
How would you do it in a non-Tridion based website?
Tridion does not provide user login/logout functionality, so you can choose whatever method best fits your requirements, technology and expertise.
The Audience Manager module will allow you to store and retrieve contacts, which you could leverage as a user database for your functionality, see the documentation link, "Contact Subscription" for more information.
If you use modules such as Audience Manager, Profiling and Personalisation, SmartTarget etc. then you can synchronise your users' information and preferences with Tridion in order to implicitly and explicitly target/personalise your content and get the most from it.
You can do the registration/login/logout in few ways. depends on how and where you want to maintain the users (user profiles in tridion are stored in TRUSTEES table in the tridion schema/DB) 1st approach, If you want to use an external authentication system, 1st would be to hook up the IIS with a policy server (ex: siteminder). and synchronize the users in tridion to that external system You can provide the registration form that would post the user details to tridion schema and create the user profile ther and have the users enabled by CMS admin by putting a process around it. Once user is enabled in tridion, that gets synchronized with the external system and the policy server will handle it. Lot more happens with the above setup.
2nd approach To simplify it, you can just have the CMS admin enable the registered user and the login button can be posted to a logic that checks if the user id is active in tridion and redirect to tridion dashboard page. If user is still not enabled, he can be routed to a sorry page.