How to recognize user when logged in using different ways [closed]

Question

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.

Closed 8 years ago.

SO is using multiple ways for user to get logged in, like using emails addresses from gmail, yahoo, facebook, stackexchange and open ID.

User might can use e.g; gmail and enjoy SO for few days and then due to any or some reason (I assume, he forgot actual way), he starts using facebook. Now SO will have multiple records for same user. Is there any way, sites can recognize there old members ?

Its just a confusion, I am curious about the concept. Like one way to register and login would be enough and would help to keep member's SINGLE record for the life. I would prefer site's own registration and login forms.

Answer 1

You cannot recognize a user when "logged in" using different ways. Unless you ask the user to link the different ways to ONE user profile. StackExchange makes this possible, you can simply add another OpenID identity to your user.

As soon as you enable user authentication through OpenID or OAuth for your service you WILL have this challenge and can either choose to solve it by enabling "linking" of identities to a user artifact, or you can choose to ignore it.

Are you confused about the benefits of OpenID?