Module envelope 

What flows through the stream: the position in the source’s change feed and the envelope a lane carries for one document.

A Position is assigned by the source, monotonic for the life of the source instance (across reopened streams, so a restarted ingest engine never reuses one), and meaningful only to the source that issued it (the Postgres adapter maps it back to an LSN). The stream orders positions to compute its watermark; the ingest engine hands the watermark back to the source as confirmation.

An Envelope is one document operation as every sink receives it: the index, the operation, the document id, the document itself (absent on a delete), the position of the change that produced it (absent for a snapshot row, seq on the wire), when it was built, and — stamped on the sink side — the emitting sink’s name and a meta summary. Emitting sinks forward it as-is; a consumer deserializes the same type over its own document type.

use kernel::{Envelope, Op, Position};

let position = Position(42);
assert_eq!(position.to_string(), "42");
assert!(Position(41) < position);

let json = serde_json::to_string(&Op::Upsert).unwrap();
assert_eq!(json, "\"upsert\"");

Structs

Envelope

One document operation as a lane carries it and a sink receives it.

EnvelopeMeta

At-a-glance facts about a serialized document.

Position

An offset in the source’s change feed: opaque to everyone but the source, ordered so the stream can take a minimum across lanes.

Enums

Op

What happened to the document.

Constants

ENVELOPE_VERSION

The envelope format version, bumped when a field changes meaning.