How to do rest authentication with Spring Social?

I have implemented Spring Social + Spring Security as outlined in the Spring security examples (and with spring security java config). I reported couple of problems at the time (see https://jira.springsource.org/browse/SEC-2204) all of those are resolved and my security works fine.

However, I want to change my security implementation and use RESTful authentication. Spring oauth/oauth2 (http://projects.spring.io/spring-security-oauth/) solves this problem but I can not see how Spring Social will fit into that picture? Although behind the scenes Spring social talks to Facebook/Twitter with oauth, I don't think Spring Social's signup form and other characteristics are built for a restful API.

Any examples or ideas will definitely help.

Update on this post: (4/6/2014)

• I have built a (PHP) site that consumes my API.
• This PHP site (let's call it the client site), uses Facebook PHP SDK to register its own users. This is a completely separate way of gathering its own members.
• However, once users are registered client site passes username, email, password, first name, and last name data along with its client_id and client secret and using OAuth2 grant type client_credentials authentication.
• This passed-in user data creates an user record on the main system! (main application)
• After this, each time the client site calls the main system via OAuth2 grant type password and sends client_id, client_secret, username and password, gets an "Authentication token" and be able to communicate with the main site with this token.

Seems like a long way to go but solves the problem of keeping the user record on the main system. I'm curious if there are other ways to do this? Please advise.