This is something I wondered about the federated microblogging platforms that I never got a clear answer about. It’s less relevant to Lemmy as federation here is broken down by community and not the entire instance, unlike the microblogging sites. If I have a Mastodon instance named myinstance.com and I follow someone or interact with a post on remoteinstance.com, according to the documentation, our instances have “discovered” each other. myinstance.com will fetch all posts from remoteinstance.com from that point onwards and display them in the federated timeline. But does this mean that the users on remoteinstance.com will also fetch posts from myinstance.com if no user on remoteinstance.com has interacted with myinstance.com before?
@Andreas Actually, it’s none of the above, but if you wat it is more on the one-way side.
First important thing: Not whole instances federate (all their stuff) with each other, but just users/ groups/ communities/ magazines. All of these are “actors” and the https://activitypub.rocks/ protocol is designed about them exchanging information.
This exchange is mostly push-based along follow/ subscription relationships. This is what makes it mostly one-way.
Replies are delivered explicitly.
@Andreas Furthermore, fetching and pulling data back is also possible, but for scalability reasons only happens for minor specific cases.