facebook offline_access与access_token

Question

I have read Q&As in here and other threads to understand how facebook handles offline_access and I am still not completely understanding how it works, so please someone explain to me.

Seems like facebook still supports client apps to access user info without having to ask user to log in everytime. (if authorization is granted by user at least once during installation of client app, for example)

The access_token which enables all this seems a bit confusing to understand correctly.

I see that in c# code, access_token is read-only property so client app can't save and reuse, client app has to ask for the token on behalf of user everytime to the authorization server (facebook server). Then there are people saying offline_access (access_token with long term use, expiration period about 60 days) is necessary and some people say default access_token (1-2 hours) is good enough, you just ask for it each time.

Can anybody clarify and please provide some C# code or link containg code?

Thanks in advance

Answer 1

If you have offline_access selected when the user is giving your application permission, all it means is that the access_token that is returned has a long term life - this means that you don't need to re-issue an access_token to make posts (or whatever) on their behalf. Without offline_access , you would need to re-issue the access token each time you wanted to do anything to their account.

If you were to use the 2 hour access_token , when that expired, the user would need to log into Facebook before a new access_token could be issued - meaning you'd need to redirect them to the Facebook login page and then a the token would be sent back to you. It's a less convenient method, however I've had nothing but struggles trying to use the offline_access option