How does comment federation work?
How does comment federation work?
I'm sure this question has been asked and answered many times, but I can't seem to find the info.
My naive understanding is that a given community lives on a certain server. For example, this post is at lemmy.ml: https://kbin.social/m/[email protected]/t/107757/Is-anybody-else-more-active-here-then-they-were-on
Then, I figured that when I visit that post from kbin.social, I figured it would pull the comments from the lemmy.ml community and that no matter where you view a post, the comments would (eventually) be identical. However, the comments are very different at https://lemmy.world/post/746839 which makes me think that I have a pretty fundamental misunderstanding with how things work.
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Two big things:
Time - Federation takes time. Especially if servers are overloaded or haven't allocated enough federation workers. Both of these things have been true at some point for most instances since the population boom.
Defederation - Different instances can defederate from other different instances. So say for example I have three instances, lemmy.one, lem.two, and kbin.three. In this example, lemmy.one has defederated from kbin.three and the post in question is on lem.two/c/community.
You now have three scenarios:
- A user visits lem.two/c/community and sees all the content.
- A user visits kbin.three/m/[email protected] (or however kbin does cross instance URIs, I'm not familiar). This user sees most of the content. The limited factor here being time.
- A user visits lemmy.one/c/[email protected]. This user sees most of the content, but no comments from kbin.three because of defederation.
And I could be wrong, but I believe vote federation is separate from comment federation, so if that takes more time, then the comments sections might look different even if they have the exact same comments because of vote sorting.
Time - Federation takes time. Especially if servers are overloaded or haven’t allocated enough federation workers. Both of these things have been true at some point for most instances since the population boom.
Is this why I often don't see reply notifications?
That's an excellent question, I have no idea.
Me neither. Didn't see your reply either. Had to go back to the comments here to find out.
Wonder if it's a kbin/lemmy thing, because I think I receive a notification for 1/50 replies.