Module message 

Draft-19 control message encoding and decoding.

Key differences from draft-18:

• Request ID field removed from GOAWAY entirely; the control-stream and request-stream forms are now identical.
• New Range Filter parameters (length-prefixed): SUBGROUP_FILTER (0x25), OBJECTID_FILTER (0x26), PRIORITY_FILTER (0x27), OBJECT_PROPERTY_FILTER (0x28) and TRACK_PROPERTY_FILTER (0x29).
• New Setup Options MAX_FILTER_RANGES (0x06) and MAX_REQUEST_UPDATES (0x08); both are even KVP types carrying a varint value.
• GROUP_ORDER (0x22) moves from PUBLISH_OK to SUBSCRIBE_TRACKS (the wire encoding of the parameter is unchanged).
• PUBLISH_BLOCKED renamed to PUBLISH_SKIPPED (still type 0x0F; wire identical).
• SUBSCRIPTION_FILTER renamed to LOCATION_FILTER (still parameter 0x21).
• REQUEST_ERROR adds CONFLICTING_FILTERS (0x35) and INVALID_FILTER (0x36); DUPLICATE_SUBSCRIPTION (0x19) is removed.
• The framing field after Message Length is named Message Body (draft-19 Section 10, Figure 3); earlier drafts called it Message Payload. The change is editorial, so the bytes are unchanged, but this module uses the new name.

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::status_code field.

request_error_codes

REQUEST_ERROR error codes with dedicated meaning.

Structs

Fetch

FetchOk

FETCH_OK (0x18). end_of_track is uint8.

GoAway

GOAWAY (0x10). Draft-19’s GOAWAY has no Request ID field, so the control-stream and request-stream forms are identical on the wire. Draft-18 is the one draft that carries the field, and only when the message is sent on the control stream.

Namespace

NamespaceDone

Publish

PublishDone

PUBLISH_DONE (0x0B). Status codes 0x5/0x6 are swapped vs draft-17.

PublishNamespace

PublishSkipped

PUBLISH_SKIPPED (0x0F). Drafts 17 and 18 name the same codepoint PUBLISH_BLOCKED, with the same two fields.

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 (Section 10.2.17), which on drafts 15 through 17 may appear on SUBSCRIBE_NAMESPACE instead.

TrackStatus

Enums

ControlMessage

FetchPayload

FetchType

MessageType

ParamEncoding 🔒

How a parameter value is encoded on the wire.

Constants

AUTHORIZATION_TOKEN 🔒

IMMUTABLE_PROPERTIES 🔒

Immutable Properties, Property Type 0xB.

KNOWN_SETUP_OPTIONS 🔒

The Setup Option types this draft defines.

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_parameter_scope 🔒

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

check_ranges 🔒

Refuse a FETCH whose range ends before it starts.

check_subscription_filters 🔒

Hold every LOCATION_FILTER parameter to the filter structure it names.

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_kvp_delta 🔒

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

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-19 lets Message Parameter key appear in message.

parameter_may_repeat 🔒

Whether a message may carry key more than once.

track_property_value_in_range 🔒

Whether value is inside the range draft-19 allows for a Track Property type that restricts one.

uint8_value_in_range 🔒

Whether value is inside the range draft-19 allows for a uint8-valued parameter.