Warning! I\'m on a bit of a fishing trip here, and I\'m not even sure if the questions that I\'m asking entirely make sense. Please be kind with your responses! :)
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Please note that "Is there a way to make OpenSSO/OpenAM talk to Database for its authentication and authorization?" is phrased wrong. The question details and answers only deal with the authorization aspect. OpenAM works great with a MySQL database of users and passwords (authentication), and can use it's hidden/embedded LDAP server for storing policies and other settings.
It sounds like you still need to flesh out your security model, but you will likely find you do not need something like OpenAM at all, and can just use container/framework provided security.