I don’t if someone here does the same functionality as the tripadvisor.com has done. Basically, when you visit http://www.tripadvisor.com it will automatically detect your FB user detail (if you are currently logged in on FB as well) without asking you to authorize their app. I’m trying to find out how do they do that for almost 4 days but to no avail. I believe as per the FB OAuth 2.0 you have to grant/authorize an app before getting user info/details etc. I would really appreciate if someone could help me on this matter.
Thanks!
Facebook currently allows 8 other companies (including TripAdvisor) to read your public Facebook data as part of its “Instant Personalization” pilot program.
Facebook’s FAQ:
https://www.facebook.com/help/?page=202975766411357
If you are interested in the technical details, you might start with this blog post reviewing the program’s security vulnerabilities:
http://gdeglin.blogspot.co.uk/2010/09/risks-of-facebooks-instant.html