Login from YII website to ROR website

I am working on two sites one is in ruby on rails and other is in YII. I want to connect my YII website with ROR website. Like user can login from YII website to the ROR website. If user is login first time from YII website ROR login window will open then he will need to enter email and password and after login into the ROR website, YII website will receive the response and next time user will login directly after clicking on the button. Same as we use Facebook login into our website. I am using Devise login in ROR website. Is there any easy way to integrate this? Anyone please suggest