To be more specific:

I'm actually trying to integrate to Baseacamp using their new Basecamp api which supports OAuth 2.0. and thx to their poor resources & documentation i'm stuck at #4 of this [documentation](https://github.com/basecamp/api/blob/master/sections/authentication.md#oauth-2-from-scratch) which says i have to make a backchannel request to get the access token (i have successfully completed 1-3 steps which means i have the verification code and state).

So if anyone have any idea about this beast then pls help me fight this ;)

I have used jso OAuth 2.0 lib which helped me complete 1-3 steps but this lib uses **implicit authentication grant** and basecamp uses **authorization code grant**. So i guess i have to do some manual client-server dance which is why i need to know what this Back Channel request means and how to make one?