Is it possible to use a combination of authentication systems in a web app?
I want to use OpenId, however I think my potential customers are actually more likely to have a Facebook ID.
Therefore I wonder if it is possible to offer both types of authentication?
For nearly every language there should be a Framework! You can chain/wrap the functionality of that frameworks to statisfy your needs!
In pseudocode:
If you use java, Acegi/Spring Security might be the best way (Security which isn’t inversive – via AOP). There you can use openID and define an own second validator for yor own userdb!