Bluesky

Bluesky is an initiative to develop a decentralized social network protocol. Organized by Twitter as a non-profit initiative, it was announced in 2019 and is in a research phase as of 2022. Bluesky is owned by the team itself, without any controlling stake held by Twitter. https://en.wikipedia.org/wiki/Bluesky_(protocol) cf Open Social Networking Model

Federation Architecture: The AT Protocol is made up of a bunch of pieces that stack together. Federation means that anyone can run the parts that make up the AT Protocol themselves, such as their own server. The three main services are personal data servers (PDS), Relays, and App Views. Developers can also run feed generators (custom feeds), and labelers are in active development.

Why would you want to run one of these services?

• You’d run a PDS (Personal Data Server) if you want to self-host your data and keys to get increased control and privacy.
• You’d run a Relay if you want a full copy of the network, or to crawl subsets of the network for targeted applications or services.
• You’d run an AppView if you want to build custom applications with tailored views and experiences, such as a custom view for microblogging or for photos.

Records are stored in repositories. Repositories run as a service, exposing HTTP and WebSockets. They then can then talk to each other and federate the records. These are often called PDSes, for “Personal Data Server.” Users either run their own PDS, or use one that someone else hosts for them. Applications can be built by looking at the various records stored in the network, and doing things with them. These services all called App Views, because they are exposing a particular view of the information stored in the network. This view is created via the Lexicon system: building an application means that you define a Lexicon, structuring the data that you want to deal with, and then look at records that use your lexicon, ignoring the rest. Now, if this were all there is, there would be pretty serious scaling issues. For example, if every time I post a new update on BlueSky, if I had to send my post to every single one of my followers’ repositories, that would be extremely inefficent, and make running a popular repository very expensive to run. To fix this, there’s an additional kind of service, called a relay, that aggregates information in the network, and exposes it as a firehose to others. So in practice, App Views don’t look at Repositories, but instead, look at Relays. When I make a post, my respository won’t notify my followers’ repositories individually. My repository will notify a Relay, and my followers will use an App View that filters the ouput of the Relay to show only the posts of people they’re following. This does imply that Relays are often huge and expensive to run, however you could imagine running a smaller relay that only propogates posts from a smaller subset of users too.

First opened to the overall public Feb'2024.