membership - Store user id in Principal or Identity? ASP.Net/OpenID -

I have an ASP.NET MVC web application which is using form authentication. I am using OpenID for authentication.

At the moment I am collecting the OpenID URL under the name standard generic identity . I want to reach the database ID easily for the user.

I can create a custom provider or identity by overriding the Application_AuthenticateRequest function.

> My question is, should the user go to the UID or the principal?

Should the property of the identity name be an open-ended URL (many of these may be in the user, but I can display it on every page) or database UI?

Now I am thinking that I should only store user ID identification and open session url in session hang.

In this way I will not need a custom identification or principal.