Integration Google Apps with Ruby on rails Application

I need to integrate google apps/google service like Calendar API
and Doclist API.Anyone can advice me which gem or plugins is available
for serve all this purpose.
GDOC4RUBY gem is not working in my system.It is giving error for the
require ‘gdoc4ruby’
error message : no such file to load – gdoc4ruby
I have used gcal4ruby gem , it is working fine.But it work direct
authentication , where as I want secure authentication through authsub
Please give me advice for fulfilling my requirement.

Thanks in advance