Authenticating UserService FROM appengine

Is it possible to somehow log in to UserServices from appengine WITHOUT redirecting the user to the standard login page?

I know you can use ClientLogin from the clientside, but can i use it to log in from a servlet running on appengine?

Lets say i have LoginServlet wich accepts POST-data (user/password), can i use ClientLogin from that servle开发者_开发问答t to authenticate? Or is there perhaps another way.

Thanks

No, this is not possible and for a good enough reason that the app can literally steal the password. Standard login page is safe way to authenticate and grant permission for an app. You can do things like loading the login page in a frame inside your servlet or customize login page to an extent by changing your app details like name etc.

It's possible. I remember that I read it once inside "Google Research of Federated Login UI article".

Check this :

1. Federated Login Link under "Relying Parties - Designing a Scalable Login User Interface"

2. and this: UI Guidelines Federated Login.