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Top-level
 The thing you often get seen thrown around is "it's amazing, I had no idea a decentralized protocol could just work like that! How on earth did they solve that in a decentralized system and so FAST too!" It's simple: all those things "just work" because Bluesky is centralized. 443 comments
In every meaningful way from a power dynamics perspective *EXCEPT* the category of "credible exit" (which I am saying and agreeing is a good idea!) Bluesky is centralized. MAYBE another big corporation could come along and host all this stuff but that's adding a Bing to our Google Yes, you can host your own PDS. You can also host your own blog. But try hosting your own PDS and NOT hosting a relay or AppView and you can't do much. Blogs are decentralized, Google is not. We're getting to the point where we get to why I'm so damn frustrated about this and have been biting my tongue until it nearly comes detached from my mouth: users THINK Bluesky is decentralized because they're TOLD Bluesky is decentralized AUGH! *That's* what drives me nuts. @cwebber if theres one frustration i have trying to mature a tech thing the last few years its that "maybe this could work in the future" seems to be a much much bigger draw for people than "this is actually working now and we can use it if only we do X". it suckssss. like imagine if mastodon was only mastodon.social lol Here's an example of this problem in action fry69: "The working search box was the second thing that impressed me on Bluesky, I thought that was not possible with a decentralized model" Sorry fry sixty-nine I regret to inform you the reason search works so well is that it's centralized! THAT'S WHY So hold on, let me set some terms for "decentralization" and "federation" that I think are reasonable. > Decentralization: the result of a system that diffuses power throughout its structure, so that no node holds particular power at the center. Pretty reasonable. Do you agree? I hope so! Okay how about "federation" now because this is a *technical term* that the *fediverse has established* and I'm kinda PO'ed about the goalposts being moved on this one. A lot of people coming to Bluesky have never heard of "federation" before in a social network so listen up this is important! Here's my definition of federation: > Federation: a technical approach to communication architecture which achieves decentralization by many independent nodes cooperating and communicating to be a unified whole, with no node holding more power than the responsibility or communication of its parts. Now historically, federation has been achieved on the fediverse via "message passing". Actually, this is to the degree where I just always associated message passing with federation, but really, federation is about the distribution of power, creating an abstract whole in a sea of autonomy. Maybe there is another way to achieve federation, but it's about the power dynamics. It's a technical immersion of power dynamics, the flow and interchange of cooperation between many parts. So you may say, well, doesn't ATProto have that? After all, messages flow through the different parts! ActivityPub, as it turns out, follows the actor model of computation. Okay, many people implementing the fediverse don't know about the actor model aspect of ActivityPub but I am here to tell YOU, dear reader, that it is an important thing, not a detail I'll take one more note about federation which is that often time the message passing mechanism of the fediverse is often called "federation", but theoretically another mechanism could exist, but I'm actually not so sure of that. There's a reason the actor model and the lambda calculus are undying Oh god Christine said "the lambda calculus" did you know she's into lisp and functional programming, what's she going to talk about next monads?!?! I am not going to talk about monads. Not TODAY But we do need to get a better architectural idea of how these systems work because it matters a lot!  @cwebber your spooky Halloween name next year should be Christine "Leibniz"-Webber So let me introduce two models of communication which we can use to analyze these two systems. It's important! - Fediverse/ActivityPub: "message passing" Okay, cool, terms established, let's talk about them and why they matter because they matter A LOT "Message passing" is what ActivityPub uses. It's "like email", people say, and that's true. Actually it's even a lot like physical mail. You write a letter, you say where it should go, it gets delivered to your house. Message passing. The world runs on it. Now I can use message passing to send a message to you *directly* and indeed, that's "like email". For one-to-one correspondence, that's enough. But it's not enough for a followers/following type mechanism. But we can build it on top! Thank *you* computational abstractions! On top of "message passing" we will build "publish-subscribe" as a second-layer abstraction "Your ideas are interesting and I'd like to subscribe to your newsletter." You send me a letter saying you'd like to hear the things I have to say, okay, you're part of the reader list. That's how it works. On top of that we can build even more abstractions and the net result is that this is how federation works in pretty much every "federated" system I know. ActivityPub does some extra work to help you see replies on a thread, think "letters to the editor". This is a bit lossy sometimes though It's true that sometimes users click over to a thread and see some replies but not all on their instance's UI. There's things that could be done to improve it, but it's sometimes mildly confusing, but not so bad, and you can click over typically to see whatever else is happening, and people learn to I actually think this is improvable but I mostly don't care because this isn't as big a complaint as people tend to think it is on the fediverse, the other concerns like "what instance do I pick" tend to be bigger and "oh no my server went down" That can be improved, we'll talk about that later So okay, the federation is "message passing" and like email, or physical mail. You have an idea how it works. Now we need to get to that other thing, a "shared heap" architecture. What on earth does that mean? If "message passing" is like "mail comes to your house", a "shared heap" system works differently In a "shared heap" system, all the mail gets dumped at the post office, and in the most naive version, you go over there and read through every single piece of mail to see which one is relevant to you There is no "directed delivery" in a "shared heap" system, which means you are stuck with two things: either a "god's eye view" (Bluesky) or "even lossier about replies than ActivityPub" (Secure Scuttlebutt/Nostr) The Bluesky approach to the "shared heap" is that *everything* goes into the big, centralized shared heap. Bluesky takes a "god's eye" view: it knows everything, and so knows what all your replies are, and can give you perfect search. Secure Scuttlebutt / Nostr... well long story. Lossier, I'll say You can imagine the physical world version of "message passing" already because you already live in this world. Messages come to your house or apartment building or whatever For Bluesky's "shared heap" architecture, you'd have to build a whole addition to your house for everyone's mail That's exactly why running a Relay or AppView is expensive: you're building an addition to your house for all the world's mail. Eeep! That ain't cheap. That's why I'm saying: decentralization also means the ability to *scale down*. Look, I know that I've been hitting this nail on the head for a while but: the web is open, blogs are open, but Google isn't open But you could run your own Google, in theory. You could index the web. So why aren't you? Ah yeah. Same thing here. That's what I mean, that's why it's centralized Now as I have said, this is a *design decision*. And remember: most users of Bluesky really *don't care*. Decentralization is not their focus, they're trying to get the hell off the nazi hellscape that Musk's toxic reign of Twitter has become. Bluesky's architecture, actually, is great for them. If what your *goal* is to get off Twitter, then Bluesky has solved it. They solved it by building another Twitter, and this time it's open source, which is cool! And it might have this "credible exit" thing. But god damnit it's not decentralized and it's not federated stop TELLING people that "Oh Christine you're being sensitive" Maybe, but there are real consequences to this. What if Bluesky/ATProto fails? "Oh well we tried decentralization and that didn't work." If people think something is something that it isn't, then that's a real problem. Users, clearly, think a lot more of Bluesky is decentralized than it is, and realize less of the consequences than they should. This really worries me. Blocks and DMs are both great examples of this. Blocking first. Bluesky's decision to have *everything* public means that it is expected that every participating node knows *everything* about who's blocking *everyone*. "This is consistent with how blocking works on Twitter/X" their paper says But wait, I'm pretty sure that one's not true though  @cwebber@social.coop https://clearsky.app/ is creepy as shit lol and it shows just how much is public It is ONE thing to be able to block JK Rowling and for you to see that JK Rowling is blocking you. It is an ENTIRELY DIFFERENT THING for ANYONE to see who is blocking JK Rowling and who JK Rowling is blocking This one is shocking to me: this seems like a vector for abusive actors  @cwebber@social.coop Already happening, bots scrape and harass people who sub to a labeller marking transphobes or something Now to be completely fair this is something that Bluesky's devs are interested in potentially changing: there is an open issue to discuss the possibility of private blocks https://github.com/bluesky-social/atproto/discussions/1131 What I am saying is there are architectural consequences to fundamental design abstractions Yes, I may sometimes seem silly over here, SICP-hugging fangirl, come on we're just trying to build things that *work* over here Look I'm a lisp lady, I know the realities of "Worse Is Better" more than most, I now the right CS designs don't win But Conway's Law flows in two directions! You know what, we'll come back to "bidirectional Conway's Law", let's talk about Direct Messages for a minute because I think those are telling Direct Messages in Bluesky, wait how do they work if ATProto is public? Did you guess? DMs are centralized! All DMs flow through Bluesky  @cwebber yeah, I haven't been on Twitter in a hot minute but I lived there for years and you could see things like follows and the most telling was Likes, even before they started getting put in people's TLs, you could look it up -- which were legit the first way we found out JKR was a terf, she wasn't posting it yet or RTing even but she was constantly liking terf shit. However that was the most detailed info you could get on someone, the one thing they didn't necessarily intend to share.  @cwebber I just saw this one comment, and then... clicked it and started scrolling up. Woo, time to read.  @cwebber My gourds, this thread has been a wild, insightful ride so far!  @cwebber I want to be able to speak intelligently enough on the subject, but I only learned enough about Bluesky/ATProto to know that I wasn't interested in using it. Do you think it's worth understanding to be able to explain to people? And/or is there a good brief explainer somewhere? @cwebber I have kind of an axe to grind about "decentralized" systems that are really centralized organizations using some decentralized tech. People look at the protocols and cables to evaluate centralization, but what really matters are the wider trust relationships that are a layer even below those. @cwebber Dropping in mid-thread just to thank you for it! Helps me understand things. :)  @cwebber PDSes are like your house. Relays are like telecoms.  @cwebber An analogy I've used with some folks is to imagine blogs you can only read through Google Reader. And if Google Reader shuts down, you can't read those blogs any more. But that'll never happen right? (which, of course, I see you've covered as I read further through your thread! π )  @cwebber if content addressed storage is considered a new idea then I'm done. I quit  @cwebber this is the single thing about it that drives me truly up the wall. The only ways in which BS is doing decentralization better is by centralizing. I wrote a whole rant on that thing (<https://wok.oblomov.eu/tecnologia/credible-threat-2/>)   @cwebber yeah it's literally just one big server and so they have the reasources to take on millions of users in a week, also easier when there's a single point of entry, unlike having to search for an instance, which already assumes one has a solid knowledge of not only how the fediverse works but which servers are cool and which to avoid, which for me at least took a couple years of trail and error |
Gregory's Server
Now yes, they are using decentralized techniques. Remember when I said content-addressed storage is a good idea and the fediverse should do it too? IT IS! (And as I also said, it's actually fully possible for the fediverse to do, more on that later.)
But the reality is, it's still *centralized*