App engine authentication

I am new to appengine. I will write application which consist of two parts.

1) Core written in app engine with REST interface for clients. 2) Client application written in J2EE on my other (not appengine) server. But here, client may use any other technology (android, swing etc.)

I dont know, how to handle authentication of users in this schema. I think that I am in the middle between standard login and installed applications.

The simplest solution that occured to me, that the client will request username+password, pass开发者_开发知识库 it to appengine application via https and it will authenticate.

But dont know how to synchronized the login with client app, because it will need also data from google applications...

Is there any solution or pre-prepared facility in Java how to handle this?

Thanks

You probably want to use OAuth for this; client login or using username+password is not a good way to do this, and informed users will be -- or SHOULD be -- hesitant to give away their passwords. There is a page for using OAuth within AppEngine applications written in Java which may be of use. There is also some support for Oauth in the GData client library for Java. The OAuth in the Google Data Protocol Client Libraries document may help you to understand how to use those features.