How long can I access a friend's list offline after that person connects via facebook connect?

I want be able to send a list of friends & recent additions from someones facebook account to an email address daily or weekly.

Looking up online, I think the best approach would be to setup a website, where a user would facebook connect with their facebook credentials & accept all terms including accessing their friends list. The website would then run a batch job nightly to access that persons friend list, do a matchup and then send an e-mail with the summary of their findings.

Is this possible? Can I just do a onetime login and get forever access to someones friend list, assuming they do not manually revoke access to the application within fb? looking for suggestions. I know there is way to access a profile offline, but how long is that session available for? I know the policy has changed, AND can change in the future by trying to understand the current state of accessing a friends list offline.

Also, am I violating any policies 开发者_StackOverflowby doing this?

---

You need to ask the user for an offline_access permission and read_friendlists permission, that way you'll get an accessToken that does not expire.

More info here: http://developers.facebook.com/docs/authentication/permissions

as long as you don't save data you'll be fine