551 words spilled on a simple question, with a simple, obvious answer: E-mail. * Immediacy: if a post has been made by someone I follow, I can see it in my tim

551 words spilled on a simple question, with a simple, obvious answer: E-mail. * Immediacy: if a post has been made by someone I follow, I can see it in my timeline right away (or close enough that I don’t notice the difference). "E-mail" * Chronology: posts always appear in order by time posted. "E-mail". Chronology as the author imagines it doesn't even occur for Twitter, likely their machines' timestamps are fuzzy +/- perhaps up to a minute or more. * Monotonicity: timelines grow only from the top; older posts are never retroactively inserted. So have your client mark a message by the time it's received, provide a second sort order. Ugh. "E-mail" There are genuine technical challenges to implementing a robust many-many federated messaging system, this post mentions none of them.