We've tried to take the approach that for everything you can use the REST-based JSON delivering API (https://github.com/buddycloud/buddycloud-http-api). The federation, domain discovery, message passing between domains, dial-back security etc are all handled at the XMPP layer and can essentially be a black box. Just know that your posts, media, whatever-you-want will get delivered when both domains are online and that servers will catch up on posts when one goes down.
To me this gives developers the best of both worlds - simple to develop web-app combined with solid, tested, it-just-works federation.
We've tried to take the approach that for everything you can use the REST-based JSON delivering API (https://github.com/buddycloud/buddycloud-http-api). The federation, domain discovery, message passing between domains, dial-back security etc are all handled at the XMPP layer and can essentially be a black box. Just know that your posts, media, whatever-you-want will get delivered when both domains are online and that servers will catch up on posts when one goes down.
To me this gives developers the best of both worlds - simple to develop web-app combined with solid, tested, it-just-works federation.