A requirement to use the RPXNow is to set your Facebook application's connect url to http://mydomain.rpxnow.com.
I was just trying to implement Facebook's Open Graph and I see that it tells you to set the Base Domain to the domain that will contain the app_id.
However, Facebook does not allow these two domains to look different. When I try to set the base url to mydomain.com, I get this error:
Validation failed. Base Domain is not valid. Connect URL must be derived from your Base Domain.
Should I create two apps - one for use with RPXNow, and another for use with Open Graph? If not, what should I do?
Thanks
The Facebook page regarding Base Domains you linked to states the following:
Facebook Connect stores user credentials in cookies on your application's domain. By default, a cookie set on chicago.citysearch.com would not be readable on sanfrancisco.citysearch.com - the browser treats them as separate domains. If the base domain is set, then Facebook will intentionally set the cookies on the base domain, thus making the cookies readable across multiple subdomains. This allows you to share one authentication session across multiple subdomains. Note: There is no way to share a cookie across multiple domains. So, for example, if you have a site cnet.com and news.com, then there is no way to make the browser send the same cookies to both those domains. Each of these would require separate API key and separate authentication.
Since your domain and rpxnow.com are different base domains, it seems like you'd need a custom realm (eg. login.yourdomain.com), which is offered from RPXNow at additional cost. You'd probably have to upgrade to "Pro" account (~$95/mo+ ?) or contact RPXNow / Janrain directly and ask them your options.