Social graphs are a well-understood technology. Using infrastructure and standardized protocols that are usually de facto controlled by large, commercial platforms, they provide a way of structuring and querying data about individual nodes (often users) in a network and the relationships (edges) between these nodes. They are theoretically extensible, and social graph data can typically also be represented using open standards like RDF which can be published and consumed by other authorities participating in a network. However, trying to enable participation or federation this way is frequently wishful thinking, and does not really facilitate scaling that social graph beyond a particular API representation of rows in one organization’s database.

The Atmosphere — built on AT — presents a different approach. When you write data using Atmosphere APIs, such as by posting to Bluesky, that data is associated with your personal data repository. These personal data repositories can be hosted or migrated anywhere across the Atmosphere. Each Atmosphere app declares its own schema (Lexicon), and reads and writes its own set of fields. These fields can be read by any other app built on the Atmosphere, allowing users to both a) own and b) span their graphs across the network.

This enables several in-demand use cases. Building “big world” social apps with AT is only a matter of creating new lexicons to support additional data models, designing app views which serve this data (along with any other data that may already be available to a user’s graph from other AT apps), and self-hosting the necessary infrastructure.

We provide implementation patterns, along with primitives and tools that are of interest to almost all implementers — like OAuth Scopes and moderation tools. We also provide a social networking app (Bluesky Social) that serves as both a reference implementation for the protocol, and a critical-mass opportunity to populate users’ social graphs so that other application developers can benefit from shared data. Regardless of which application is using this data, all of it is open, public, and associated with individual users’ data repositories, which can be migrated across the network at will.

This talk will provide a demonstration of some fundamental AT technologies, including: "Sipping the Firehose" - working with the stream, a demo of creating records and have them pop right out “Getting backlinks with Constellation” - querying social interactions in real time, and building that data into different interfaces “Lexicon Authoring” - a discussion of best practices for creating additional schemas, with examples from other apps in the Atmosphere