Thesis full text PDF (in Italian) - Politecnico di Milano

Second registration phaseThe memorization of the new user’s information is performed by the servlet“UserRegistration” (fig. 26), that receives data through a client POST.The method “checkUserRegistration()”, evaluates if the user is already presentcalculating a hash function over the email’s value (in this way is created the user’sidentifier), and making a comparison with all the ids of the users registered.If the user is not present, the registration of the new data is performed, and aconfirmation page is showed, else, the user is redirect to a fail page, showing thefailure’s motivations.Figure 26 - Class diagram related to the servlet“UserRegistration”Whether the user provides also his Facebook’s id, between the registration phaseand the confirmation page visualization, some additional steps has to becomputed, this due to the fact that with Facebook, by default, an application canaccess all the user’s profile general information (including name, profile picture,gender, etc.) but, if it needs to access others information, that may be private, an“extended permissions” request, has to be performed.In order to authorize the application to get access to the user’s id, the Facebookplatform uses the OAuth 2.0 12 protocol, associating to each user an access token,used to get information from his profile.12 OAuth 2.0: is a simpler version of OAuth that leverages SSL for API communication instead ofrelying on complex URL signature schemes and token exchanges.73