We have a website application that is deployed and customised for multiple customers, across different domains, we are developing a Facebook Connect app within this website, so people can see what their friends are doing through our sites.
I've set the site url and canvas url in my Facebook app to my localhost for debugging, I was wondering, what if I wanted to use this application across multiple domains? Will facebook only allow postback to one domain per application? Is it possible to configure multiple domains?
EDIT If this isn't possible how are large companies managing multiple domains? Will it have to be setup as one domain per application or is there a way to programatically add a new application through code?
EDIT There is further discussion on this issue here
Unfortunately, the September 30, 2011 blog post is worded in a misleading way. The relevant section is "Support for Multiple Domains in the Developer App." Reading that paragraph, it would appear that there are no restrictions in terms of which domains can be lumped together under one application.
However, when I tried adding a second domain to an existing application, I received an error message saying that the new domain must be derived from the Site URL. One comment on that blog post described a similar experience. And that restriction was confirmed by a reply to that comment by someone in Developer Relations at Facebook, explaining that "All app domains must be derived from the site URL."
I believe the confusion arises from incorrect wording in the post itself, which says "Your App’s URL (Website and/or Mobile Web URL) must be derived from one of the domains listed in the App Domain field."
*Update: Just to clarify what types of domains are allowed, let's say your Site URL is "mywebsite.com". You would be allowed to add "mywebsite.co.uk" as an additional App Domain, but you would not be allowed to add "myalternatewebsite.com".
I got a partial solution for this! Using this you can add one more domain that is you can have two different domains(independent of each other). On the Basic settings tab, look for Mobile web url. Add a url of your app on different domain and then try adding this domain in App Domains. Hope it helps(little bit).
来源：https://stackoverflow.com/questions/7553607/is-it-possible-to-configure-a-facebook-app-to-be-used-across-multiple-domains