Glossary #

Key terms used throughout the HappyView documentation. For a broader introduction to the AT Protocol, see the official ATProto glossary.

AT Protocol terms #

AppView — A backend service that indexes AT Protocol records and serves them through an API. HappyView is an AppView. See the ATProto docs for more.

DID (Decentralized Identifier) — A persistent, globally unique identifier for an account (e.g. did:plc:abc123).

Firehose — A real-time stream of all record events (creates, updates, deletes) across the AT Protocol network. HappyView consumes this via Tap.

Handle — A human-readable name for an account (e.g. user.bsky.social). Handles resolve to a DID via DNS or the PLC directory.

Lexicon — A schema definition for AT Protocol data types and API methods. Lexicons define what records look like, what endpoints exist, and what parameters they accept. See Lexicons.

NSID (Namespaced Identifier) — A reverse-DNS identifier for a lexicon (e.g. xyz.statusphere.status). The authority is everything except the last segment.

PDS (Personal Data Server) — The server that hosts a user's data. Users can be on any PDS — there's no single server. HappyView proxies writes back to each user's PDS.

PLC directory — A public service (e.g. plc.directory) that maps DIDs to their DID documents, which contain the user's PDS endpoint and other metadata.

Record — A single piece of data in an AT Protocol repository, identified by an AT URI (e.g. at://did:plc:abc/xyz.statusphere.status/abc123).

Relay — A network service that aggregates repository data from many PDSes. HappyView queries the relay during backfill to discover which repos contain records for a given collection, then delegates the actual record fetching to Tap.

rkey (Record Key) — The unique key for a record within a collection and repo. These are most commonly TIDs (timestamp-based) or NSIDs.

TID (Timestamp Identifier) — A 13-character sortable identifier used as a record key. Generated from the current timestamp.

XRPC — The HTTP-based RPC protocol used by the AT Protocol. Query methods map to GET requests, procedure methods map to POST requests. See XRPC API.

HappyView-specific terms #

AIP — Authentication and Identity Provider. An external service that handles AT Protocol OAuth for HappyView. Issues Bearer tokens used for authentication.

Backfill — The process of bulk-indexing existing records from the network. HappyView discovers repos via the relay and delegates record fetching to Tap. Runs when a new record-type lexicon is uploaded or triggered manually. See Backfill.

Network lexicon — A lexicon fetched directly from the AT Protocol network via DNS authority resolution, rather than uploaded manually. See Lexicons - Network lexicons.

Tap — A firehose consumer and backfill worker that handles real-time record streaming, cryptographic verification, and historical record fetching. HappyView connects to Tap via WebSocket to receive record events, and delegates backfill work to Tap via its HTTP API.

Target collection — The record collection that a query or procedure lexicon operates on. Set via the target_collection field when uploading a lexicon.