Module draft22 

MoQT client implementation for draft-22.

Each draft lives in its own top-level module with a complete, independent implementation: connection, endpoint state machine, event types, observer trait, and per-flow state machines (subscribe, fetch, publish, namespace, track status). No code is shared across drafts — each draft carries its own copy because wire-level differences would make a shared layer leaky.

Enable via the draft22 feature.

What changed from draft-19, in the places a caller can feel it

• FETCH was rebuilt (Section 9.11). The Fetch Type field, the Standalone and Joining Fetch structures and the whole joining mechanism are gone; the Track Namespace and Track Name are inline fields, and the range travels in the LOCATION_FILTER parameter. So Connection::fetch takes a parameter list where draft-19’s took four location varints, and joining_fetch / absolute_joining_fetch no longer exist. A fill fetch stream is what replaces them; see fill.
• FILL_PARAMETERS (0x23) is new (Section 9.20.15). Its presence on a SUBSCRIBE or a REQUEST_UPDATE asks the publisher to open a fill fetch stream — a unidirectional stream beginning with a FETCH_HEADER that carries the subscription’s Request ID. fill::FillParameters builds the parameter and Endpoint::fill_requested is what tells an arriving FETCH_HEADER apart from a fetch’s.
• PUBLISH_STATE_NOTIFY (0x22) is new (Section 9.10): a unilateral report from the publisher on a subscription’s stream, answered with nothing and not counted against MAX_REQUEST_UPDATES. It arrives as ClientEvent::PublishStateNotify.
• Ranges are inclusive at both ends (Section 3.2, Section 3.3.1, Section 9.12). Draft-19’s fetch end was “the last Object, plus 1; or 0 to indicate the entire Group”; both conventions are deleted, and nothing in this module carries the arithmetic forward.
• INCLUDE_PROPERTIES (0x35) is new (Section 9.20.21): a uint8 opt-out from Track Properties on the responding OK, default 1.
• Three code points went: SUBSCRIPTION_ENDED (PUBLISH_DONE 0x3), VERSION_NEGOTIATION_FAILED (session 0x15) and INVALID_JOINING_REQUEST_ID (REQUEST_ERROR 0x32).
• There is still no version on the wire. The negotiated draft is the ALPN, moqt-22 on raw QUIC, exactly as on every draft from 15 on.

What a caller feels against draft-21

One wire change, to LOCATION_FILTER (Section 9.20.9). Its value opens with a Location Filter Type that names which fields follow, and carries no length, nested inside FILL_PARAMETERS or not. Two consequences reach a caller of fill::LocationFilter:

• {0, 0} is an absolute start, the beginning of the track. The Next Object is a type of its own, 0x05, built by fill::LocationFilter::next_object, and None is type 0x00, which is how a REQUEST_UPDATE takes a filter away.
• A type outside the six Section 9.20.9 assigns is a PROTOCOL_VIOLATION, and the codec’s InvalidFilterType is the session close Connection::codec_session_error_code gives it.

Everything else is draft-21’s, under draft-22’s numbering: every citation in this module is draft-22’s own.

What this module does not enforce

Draft-22 lists the parameters a REQUEST_UPDATE (Section 9.5) and a REQUEST_OK (Section 9.3) may carry per kind of request — an update to a FETCH, for one, carries only AUTHORIZATION_TOKEN and SUBSCRIBER_PRIORITY. The codec holds each message to the union of its lists, because the frame does not say which request it updates or answers, and this endpoint does not narrow it to the list for the request’s own kind. A parameter inside the union and outside its kind’s list is accepted here.

Modules

connection

Outbound MoQT connection with MoQT framing over QUIC.

endpoint

Draft-22 MoQT endpoint.

event

Client event types emitted by a MoQT connection.

fetch

Fetch lifecycle state machine.

fill

Location filters and fill fetch streams, the two things draft-22 asks a subscriber to build byte by byte.

namespace

Subscribe/Publish namespace state machines.

observer

Connection observer trait for receiving structured events.

publish

Publish lifecycle state machine.

session

MoQT session lifecycle management.

subscription

Subscription lifecycle state machine.

track_status

Track status lifecycle state machine.