Question

I’m currently developing a web application with Spring Social and Spring Security. In the web application, specific users can signin on Facebook with ProviderSignInController. When staff members authenticate with FB successfully, they are programatically signed in for my local webapp with Spring Security, too. This concept is adapted from the spring-social-showcase. Spring Social then enables authenticated users to create Events, which are also created on a facebook page.

Now i want to write a android app which enables users to post to my guestbook and view/create events via my web application. My question now is how to realize the signin from my andoid app. On my web application, a UsersConnectionRepository maps facebook accounts to local accounts. Can i simply reuse this data and signin from my android app in the exact same way as from the web application?
ProviderSignInController adds a path mapping for http://_webapp_/signin/facebook which redirects to a facebook signin page. Can this simply be done with a WebView on android?

Looking on the spring-android-facebook-client im confused. This example seems to manually manage the OAuth authentication. But i havent figured out yet, whether this is the way to go or just another possibility to implement it, when there is no other web application in the background that already manages the authentication.

Any feedback is welcome. Thanks.

Jeyp

Answer 1

Now i want to write a android app which enables users to post to my
guestbook and view/create events via my web application.

The Android client will need a method to sign in to your web application in order to post to a secured RESTful endpoint, and OAuth is a good method for doing this. Spring Security OAuth is an extension of Spring Security that can allow third party mobile or web clients to interact with your web site.

Once you have an OAuth server configured, you can create a custom provider using Spring Social within your Android client to establish an OAuth connection to your web site. Your users will authenticate to your web site with their local credentials in this case. Once connected, your Android app can then post events to RESTful endpoints within your web site, again using your custom Spring Social API bindings.

In this scenario, your users do not authenticate to Facebook from the Android application. This assumes they have already established an account and a connection to Facebook on your web site. And in fact, this is how the SpringSource Greenhouse reference application works.

This brings us back to a previous part of your question:

When staff members authenticate with FB successfully, they are programatically signed in for my local webapp with Spring Security, too.

If I understand correctly, you are asking to authorize your Android client to access your third-party web site, with Facebook credentials. While this is certainly possible, it is not currently supported through Spring Social and Spring for Android.

Another option is to consider a mobile version of your web site. That way Android and other mobile devices can then simply sign in to your site just like from a normal browser, using their Facebook credentials. The UI would be more appropriate for mobile devices, and it would eliminate the extra complexity of an additional OAuth server/client configuration.

And finally, to address the last part of your question. This is really a separate issue from the previous parts:

This example seems to manually manage the OAuth authentication.

The primary issue is that Spring Social does not yet support Resource Owner Credentials Grant (ROCG). The addition of this feature would simplify the process of obtaining an access token for Facebook on Android, because you would not have to deal with a browser redirection. See this Spring Social issue for more information.

Because of the lack of ROCG, the Spring for Android sample app is illustrating one method for obtaining the access token using Spring Social. In this case, it is a modified version of the client-side authentication flow. For reference, Facebook has a helpful page describing all the available authentication methods. The webview redirects to a url after successful authentication, at which point the app is able to retrieve the access token from this url.

SpringSource is discussing how to simplify authentication and improve this part of the integration between Spring Social and Spring for Android in future releases.