We are using Echo (aboutecho.com) so that users can add comments by logging in through Google, Yahoo, AOL, and OpenID. Echo does this by using JanRain.
All is well except Facebook is missing, but to add Facebook login, we need to change the Facebook app's Base URL to oursite.rpxnow.com (rpxnow is JanRain's website)
It works except, is it true that the website's existing method of using Facebook Connect to log user's in will stop working? Because the existing Facebook login need to match our domain, such as www.oursite.com, as registered in the Facebook app setting, but JanRain also wants to change that to oursite.rpxnow.com? Since Facebook can only accept one domain, it will choke on one or the other? thanks.
If you are using Janrain Social Login(Engage) then you will be replacing the Facebook Connect method with the Janrain authentication method.
When you use Janrain Social Login you will get back a Janrain Social Login oAuth token. This token can be used to retrieve the user's normalized payload of data from the successful authentication event through thisAPI endpoint: (https://{your-engage-domain.com}/api/v2/auth_info). There are code samples for this on the Janrain website.
This payload will contain the oAuth token for the user's Facebook authentication that you can use to perform additional calls against the Facebook API.
Janrain Social Login also supports this API Call: (https://{your-engage-domain.com}/api/v2/add_or_update_access_token) which allows you to use a token generated using Facebook Connect (assuming you are using the same Facebook Application ID for both Facebook Connect and the Janrain Social Login) and add or update the Facebook token stored by Janrain's server.