Single logon with different applications approach ruby on rails
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What would be the best approach in the following situation:

 - Main application that handles authentication of users (preferably Devise).
 - Several different applications that can access user database for single logon.
 - Synchronisation of user data (Preferences, profile data)

Scenario example:

 - User registers for application A
 - User can access application B with same credentials (But has to explicitly confirm a new agreement before it can also use application B)

