Module message 

Draft-20 control message encoding and decoding.

Key differences from draft-19:

• FETCH (0x16) is a different message. The Fetch Type field is gone, and with it the Standalone Fetch and Joining Fetch structures and the Fetch Type registry. Track Namespace and Track Name are inline fields of FETCH, and the range travels in the LOCATION_FILTER parameter (Section 10.13, Figure 16).
• PUBLISH_STATE_NOTIFY (0x22) is new and carries no Request ID (Section 10.10, Figure 13).
• LOCATION_FILTER (0x21) has a new value shape. The Filter Type enum is gone; the shape comes from how many vi64 fields the value holds (Section 5.1.2).
• FILL_PARAMETERS (0x23) is new: a length-prefixed parameter carrying a nested parameter block in its own scope (Section 10.2.15).
• INCLUDE_PROPERTIES (0x35) is new: a uint8 restricted to 0 and 1 (Section 10.2.21).
• Parameter applicability moved off PUBLISH_OK. Six definitions dropped it and several gained PUBLISH; only EXPIRES still names it.
• PUBLISH_DONE’s SUBSCRIPTION_ENDED status (0x3) and REQUEST_ERROR’s INVALID_JOINING_REQUEST_ID (0x32) are unassigned here.
• Section numbering shifted from Section 10.10 on; every reference in this module is draft-20’s own.

Re-exports

pub use crate::error::CodecError;

pub use crate::error::MAX_GOAWAY_URI_LENGTH;

pub use crate::error::MAX_MESSAGE_LENGTH;

pub use crate::error::MAX_NAMESPACE_TUPLE_SIZE;

pub use crate::error::MAX_REASON_PHRASE_LENGTH;

Modules

publish_done_codes

Numeric values for the PublishDone fields.

request_error_codes

REQUEST_ERROR error codes with dedicated meaning.

Structs

Fetch

FETCH (0x16), rebuilt in draft-20 (Section 10.13, Figure 16).

FetchOk

FETCH_OK (0x18). end_of_track is uint8.

GoAway

GOAWAY (0x10). In draft-20 the Request ID field is removed, so the control-stream and request-stream forms are identical on the wire.

Namespace

NamespaceDone

Publish

PublishDone

PUBLISH_DONE (0x0B). The wire layout is unchanged from draft-19; what draft-20 changed is the Stream Count sentinel, what the count includes, and the removal of status code 0x3.

PublishNamespace

PublishSkipped

PUBLISH_SKIPPED (0x0F, renamed from PUBLISH_BLOCKED in draft-20; wire layout is unchanged).

PublishStateNotify

PUBLISH_STATE_NOTIFY (0x22), new in draft-20 (Section 10.10, Figure 13).

Redirect

Optional Redirect structure carried in REQUEST_ERROR with code 0x34.

RequestError

REQUEST_ERROR (0x05). Adds an optional Redirect structure when error_code is REDIRECT (0x34).

RequestOk

REQUEST_OK (0x07). Used as a generic OK response and as the alias for PUBLISH_OK / REQUEST_UPDATE_OK / TRACK_STATUS_OK / SUBSCRIBE_NAMESPACE_OK / PUBLISH_NAMESPACE_OK.

RequestUpdate

Setup

Unified SETUP (0x2F00).

Subscribe

SubscribeNamespace

SUBSCRIBE_NAMESPACE (0x50). Subscribes to NAMESPACE / NAMESPACE_DONE advertisements for namespaces matching namespace_prefix. The subscribe_options byte from draft-17 is removed; namespace subscriptions only produce NAMESPACE / NAMESPACE_DONE.

SubscribeOk

SUBSCRIBE_OK (0x04).

SubscribeTracks

SUBSCRIBE_TRACKS (0x51, new in draft-18). Subscribes to PUBLISH messages for tracks whose namespace matches namespace_prefix. Carries the FORWARD parameter (which previously lived on SUBSCRIBE_NAMESPACE).

TrackStatus

Enums

ControlMessage

MessageType

ParamEncoding 🔒

How a parameter value is encoded on the wire.

Constants

AUTHORIZATION_TOKEN 🔒

AUTHORIZATION TOKEN, Parameter Type 0x03.

FILL_PARAMETERS

The FILL_PARAMETERS parameter type, draft-20 Section 10.2.15. New in draft-20.

FILL_PARAMETERS_ALLOWED 🔒

The parameter types draft-20 Section 10.2.15, Table 6 permits inside a FILL_PARAMETERS value, in ascending order.

IMMUTABLE_PROPERTIES 🔒

Immutable Properties, Property Type 0xB.

KNOWN_SETUP_OPTIONS 🔒

The Setup Option types this draft defines.

LOCATION_FILTER

The LOCATION_FILTER parameter type, draft-20 Section 10.2.9.

LOCATION_FILTER_MAX_FIELDS 🔒

The most vi64 fields a LOCATION_FILTER value can hold: StartGroup, StartObject, EndGroupDelta, EndObject (draft-20 Section 5.1.2).

REPEATABLE_SETUP_OPTION 🔒

The one Setup Option whose definition allows more than one instance.

Functions

add_delta 🔒

Add a delta to the previous delta-encoded key.

check_authorization_tokens 🔒

Hold every AUTHORIZATION TOKEN parameter to the Token structure it names.

check_discriminators 🔒

Refuse a message whose discriminator disagrees with the fields beside it.

check_full_track_name 🔒

Hold a namespace-plus-name pair to the Full Track Name cap.

check_location_filter_fields 🔒

Hold a decoded LOCATION_FILTER to the one arithmetic rule draft-20 states about it.

check_location_filters 🔒

Hold every LOCATION_FILTER and FILL_PARAMETERS parameter to the structure its own type names.

check_parameter_scope 🔒

Refuse a message carrying a Message Parameter its own definition does not place there.

check_track_property_values 🔒

Refuse a Track Property whose value falls outside the range its type allows, wherever in the list it is carried.

decode_fill_parameters

Decode the nested parameter block a FILL_PARAMETERS value carries.

decode_kvp_delta 🔒

Decode delta-encoded KVPs with even/odd convention (for setup options and track properties). Read until buffer is exhausted.

decode_location_filter

Decode the vi64 fields of a draft-20 LOCATION_FILTER value.

decode_parameter_value 🔒

Read one parameter’s value in the shape its type names.

decode_parameters 🔒

Decode a count-prefixed list of parameters with delta-encoded types.

decode_setup_options 🔒

Decode the Setup Options of a SETUP message.

decode_track_properties 🔒

Decode the Track Properties that fill the tail of a control message.

encode_kvp_delta 🔒

Encode delta-encoded KVPs with even/odd convention.

encode_parameters 🔒

Encode a count-prefixed list of parameters with delta-encoded types.

encode_setup_options 🔒

Encode the Setup Options of a SETUP message.

encode_track_properties 🔒

Encode a control message’s Track Properties.

is_location_value 🔒

Whether bytes is exactly the wire form of a Location — two consecutive varints and nothing after them.

is_track_namespace_value 🔒

Whether bytes is exactly the wire form of a Track Namespace, with nothing after it. The same reasoning as is_location_value: the value goes out verbatim, so it has to be something this draft can read back.

param_encoding 🔒

parameter_in_scope

Whether draft-20 lets Message Parameter key appear in message.

parameter_may_repeat 🔒

Whether draft-20 lets a message carry parameter type key more than once.

track_property_value_in_range 🔒

Whether value is inside the range draft-20 allows for a Track Property type that restricts one.

uint8_value_in_range 🔒

Whether value is inside the range draft-20 allows for a uint8-valued parameter.