google app engine - OAuth2.0 server to server authentication -

i have gae application & service. authenticate users relatively easy, however, i'm not sure how authenticate servers want use services. specifically, have server access services. i'm using google login authentication (oauth 2.0) had thoughts:

1. first time, create google account server , somehow retrieve token manually server, store , refresh every time need access gae services
2. have sort of private/public key authentication. create private key server requesting services , and store public key in gae application. not sure if exists.

anyone has ideas how solve issue? thanks

i client credentials grant part of oauth 2 spec

this how twitter application-only auth, example (see https://dev.twitter.com/docs/auth/application-only-auth)

that said, think there better ways of doing server-to-server authentication 1 provided oauth2 (and not alone); think point 2 more solid alternative security difficult implement correctly! advice not (and avoid myself, if possible).

so, if find reliable implements schema, good. otherwise, stick solid oauth2 library.