Other Perspectives of Social Media: Bluesky and AT Protocol
Bluesky exemplifies a revolutionary approach to decentralized social media, grounded in the AT Protocol (ATP). Its architecture is designed to empower users with robust control over data, identity, and moderation while maintaining seamless network interoperability and performance. The three principles grounded: Simple and Powerful, User Choice, Openness.
Core Components
Personal Data Servers (PDS)
Personal Data Servers act as the backbone of Bluesky's infrastructure. They host user repositories and associated media files while providing access via HTTP APIs and real-time updates through WebSocket protocols. This design ensures low-latency interactions and supports scalability across diverse applications.
Repository Structure
Bluesky organizes user data in repositories using Merkle Search Trees (MST), a cryptographic structure ensuring integrity and version tracking. Updates are signed to authenticate changes, and all content is encoded in the DAG-CBOR format. Media files, though external to repositories, are referenced via Content Identifiers (CIDs), creating a decentralized but easily navigable content system (Bluesky, 2023b).
Identity Management
A dual-layer identity system combines:
- DNS-based Handles: User-friendly and flexible handles, e.g.,
@username.bsky.social. - Decentralized Identifiers (DIDs): Permanent, cryptographically verified identities stored in the PLC Directory. This system enables seamless migration between servers without disrupting social connections (Bluesky, 2023c).
Relay
The Relay collects updates from all known PDS repositories, validating them with cryptographic signatures. It powers the Firehose, a continuous stream of repository changes, enabling efficient data aggregation and low-latency notifications (Bluesky, 2023d).
AppView
AppView serves as Bluesky’s indexing layer. It processes user interactions such as likes, posts, and replies, organizes them into threads, and enforces moderation rules. AppView also fetches and resizes media, distributing it via a CDN to optimize performance (Bluesky, 2023e).
Labelers
Labelers provide flexible content moderation by producing judgments (e.g., spam detection) that users can adopt based on their preferences. This approach empowers users and fosters a customizable moderation framework while maintaining network neutrality (Bluesky, 2023e).
Developer Integration and Moderation Approach
Bluesky employs Lexicons, a schema system defining API methods and record types, allowing developers to build custom social modes. This includes specialized feeds, applications, and moderation services. Unlike traditional platforms, Bluesky decouples server operation from moderation, offering users control over their online experience while preserving interoperability across the network (Bluesky, 2023d).
Conclusion
Bluesky’s architectural foundation achieves a delicate balance between decentralization and usability. By integrating cryptographic repositories, modular services, and customizable moderation, it provides a cohesive yet user-centric social media ecosystem. This paradigm exemplifies the potential of decentralized platforms to offer freedom, transparency, and interoperability.
Reference
Kleppmann, M., Frazee, P., Gold, J., Graber, J., Holmgren, D., Ivy, D., Johnson, J., Newbold, B., & Volpert, J. (2024). Understanding Bluesky’s decentralized social networking architecture. arXiv. Retrieved from https://arxiv.org/pdf/2402.03239
Bluesky. (2023b). Lexicon - AT Protocol. Retrieved from https://atproto.com/docs/lexicon
Bluesky. (2023c). Community Guidelines - Bluesky. Retrieved from https://blueskyweb.xyz/community-guidelines
Bluesky. (2023d). bluesky-social repositories.Retrieved from https://github.com/bluesky-social
Bluesky. (2023e). did-method-plc: Public Ledger of Credentials.Retrieved from https://github.com/bluesky-social/did-method-plc
Bluesky. (2024). Bluesky’s Stackable Approach to Moderation Retrieved from https://bsky.social/about/blog/03-12-2024-stackable-moderation