MoQ qlog event definitions

Internet-Draft	MoQ qlog event definitions	February 2026
Pardue, et al.	Expires 27 August 2026	[Page]

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1. Introduction

This document defines a qlog event schema (Section 8 of [QLOG-MAIN]) containing concrete events for Media over QUIC Transport [MOQT].¶

The event namespace with identifier moqt is defined; see Section 3. In this namespace multiple events derive from the qlog abstract Event class (Section 7 of [QLOG-MAIN]), each extending the "data" field and defining their "name" field values and semantics.¶

Table 1 summarizes the name value of each event type that is defined in this specification. Some event data fields use complex data types. These are represented as enums or re-usable definitions, which are grouped together on the bottom of this document for clarity.¶

Table 1: MOQT Events
Name value	Importance	Definition
moqt:control_message_created	Core	Section 4.1
moqt:control_message_parsed	Core	Section 4.2
moqt:stream_type_set	Core	Section 4.3
moqt:object_datagram_created	Core	Section 4.4
moqt:object_datagram_parsed	Core	Section 4.5
moqt:subgroup_header_created	Core	Section 4.6
moqt:subgroup_header_parsed	Core	Section 4.7
moqt:subgroup_object_created	Core	Section 4.8
moqt:subgroup_object_parsed	Core	Section 4.9
moqt:fetch_header_created	Core	Section 4.10
moqt:fetch_header_parsed	Core	Section 4.11
moqt:fetch_object_created	Core	Section 4.12
moqt:fetch_object_parsed	Core	Section 4.13

1.1. Usage with QUIC

The events described in this document can be used with or without logging the related QUIC events defined in [QLOG-QUIC]. If used with QUIC events, the QUIC document takes precedence in terms of recommended filenames and trace separation setups.¶

If used without QUIC events, it is recommended that the implementation assign a globally unique identifier to each MOQT session. This ID can then be used as the value of the qlog "group_id" field, as well as the qlog filename or file identifier, potentially suffixed by the vantagepoint type (For example, abcd1234_server.qlog would contain the server-side trace of the connection with GUID abcd1234).¶

2. Conventions and Definitions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶

The event and data structure definitions in ths document are expressed in the Concise Data Definition Language [CDDL] and its extensions described in [QLOG-MAIN].¶

The following fields from [QLOG-MAIN] are imported and used: name, namespace, type, data, group_id, RawInfo, and time-related fields.¶

Events are defined with an importance level as described in Section 8.3 of [QLOG-MAIN].¶

As is the case for [QLOG-MAIN], the qlog schema definitions in this document are intentionally agnostic to serialization formats. The choice of format is an implementation decision.¶

3. Event Schema Definition

This document describes how the MOQT protocol is expressed in qlog with an event schema. Per the requirements in Section 8 of [QLOG-MAIN], this document registers the moqt namespace. The event schema URI is urn:ietf:params:qlog:events:moqt.¶

3.1. Draft Event Schema Identification

This section is to be removed before publishing as an RFC.¶

Only implementations of the final, published RFC can use the events belonging to the event schema with the URI urn:ietf:params:qlog:events:moqt. Until such an RFC exists, implementations MUST NOT identify themselves using this URI.¶

Implementations of draft versions of the event schema MUST append the string "-" and the corresponding draft number to the URI. For example, draft 99 of this document is identified using the URI urn:ietf:params:qlog:events:moqt-99.¶

The namespace identifier itself is not affected by this requirement.¶

4. MOQT Events

MOQT events extend the $ProtocolEventData extension point defined in [QLOG-MAIN]. Additionally, they allow for direct extensibility by their use of per-event extension points via the $$ CDDL "group socket" syntax, as also described in [QLOG-MAIN].¶

MOQTEventData = MOQTControlMessageCreated /
                MOQTControlMessageParsed /
                MOQTStreamTypeSet /
                MOQTObjectDatagramCreated /
                MOQTObjectDatagramParsed /
                MOQTSubgroupHeaderCreated /
                MOQTSubgroupHeaderParsed /
                MOQTSubgroupObjectCreated /
                MOQTSubgroupObjectParsed /
                MOQTFetchHeaderCreated /
                MOQTFetchHeaderParsed /
                MOQTFetchObjectCreated /
                MOQTFetchObjectParsed /
                MOQTDataStreamFin /
                MOQTDataStreamReset /
                MOQTDataStreamStopSending

$ProtocolEventData /= MOQTEventData

Figure 1: MOQTEventData definition and ProtocolEventData extension

MOQT events are logged when a certain condition happens at the application layer, and there isn't always a one to one mapping between HTTP and QUIC events. The exchange of data between the HTTP and QUIC layer is logged via the "stream_data_moved" and "datagram_data_moved" events in [QLOG-QUIC].¶

The concrete MOQT event types are further defined below, their type identifier is the heading name.¶

Some MOQT messages include a reason phrase that can provide additional information in the format of a byte sequences. However, these sequences are not guaranteed to be presentable as UTF-8. In order to accomodate various encodings, where the wire image of a message includes a reason phrase, the MOQT qlog event type, includes two option fields: reason (for UTF-8) and reason_bytes (a hex-encoded string representing raw bytes). Implementations SHOULD log at least one format, but MAY log both or none.¶

4.1. control_message_created

The control_message_created event is emitted when a control message is created. It has Core importance level.¶

The definition of control message content is in Section 5.7.¶

MOQTControlMessageCreated = {
    stream_id: uint64
    ? length: uint16
    message: $MOQTControlMessage
    ? raw: RawInfo

    * $$moqt-controlmessagecreated-extension
}

Figure 2: MOQTControlMessageCreated definition

4.2. control_message_parsed

The control_message_parsed event is emitted when a control message is parsed. It has Core importance level.¶

The definition of control message content is in Section 5.7.¶

MOQTControlMessageParsed = {
    stream_id: uint64
    ? length: uint16
    message: $MOQTControlMessage
    ? raw: RawInfo

    * $$moqt-controlmessageparsed-extension
}

Figure 3: MOQTControlMessageParsed definition

4.3. stream_type_set

The stream_type_set event conveys when a MOQT stream type becomes known. It has Base importance level.¶

MOQTStreamTypeSet = {
    ? owner: Owner
    stream_id: uint64
    stream_type: $MOQTStreamType

    * $$moqt-streamtypeset-extension
}

$MOQTStreamType /=  "control" /
                    "subgroup_header" /
                    "fetch_header" /
                    "subscribe_namespace"

Figure 4: MOQTStreamTypeSet definition

4.4. object_datagram_created

The object_datagram_created event is emitted when the OBJECT_DATAGRAM message is created. It has Core importance level.¶

MOQTObjectDatagramCreated = {
    track_alias: uint64
    group_id: uint64
    ? object_id: uint64
    publisher_priority: uint8
    ? extension_headers_length: uint64
    ? extension_headers: [* MOQTExtensionHeader]
    ? object_status: uint64
    ? object_payload: RawInfo
    end_of_group: bool

    * $$moqt-objectdatagramcreated-extension
}

Figure 5: MOQTObjectDatagramCreated definition

4.5. object_datagram_parsed

The object_datagram_parsed event is emitted when the OBJECT_DATAGRAM message is parsed. It has Core importance level.¶

MOQTObjectDatagramParsed = {
    track_alias: uint64
    group_id: uint64
    ? object_id: uint64
    publisher_priority: uint8
    ? extension_headers_length: uint64
    ? extension_headers: [* MOQTExtensionHeader]
    ? object_status: uint64
    ? object_payload: RawInfo
    end_of_group: bool

    * $$moqt-objectdatagramparsed-extension
}

Figure 6: MOQTObjectDatagramParsed definition

4.6. subgroup_header_created

The subgroup_header_created event is emitted when a stream begins and a SUBGROUP_HEADER is created. It has Core importance level; see Section 9.2 of [QLOG-MAIN].¶

The SUBGROUP_HEADER object in MoQT uses 12 type values to encode various properties. The subgroup_header_created event conveys these as explicit fields, such as contains_end_of_group.¶

If the subgroup_id is the object_id of the first object, the subgroup_id is omitted. Otherwise, it is included with the relevant value.¶

MOQTSubgroupHeaderCreated = {
    stream_id: uint64
    track_alias: uint64
    group_id: uint64
    ? subgroup_id: uint64
    publisher_priority: uint8
    contains_end_of_group: bool
    extensions_present: bool

    * $$moqt-subgroupheadercreated-extension
}

Figure 7: MOQTSubgroupHeaderCreated definition

4.7. subgroup_header_parsed

The subgroup_header_parsed event is emitted when the SUBGROUP_HEADER is parsed. It has Core importance level.¶

The SUBGROUP_HEADER object in MoQT uses 12 type values to encode various properties. The event conveys these as explicit fields, such as contains_end_of_group.¶

If the subgroup_id is the object_id of the first object, the subgroup_id is omitted. Otherwise, it is included with the relevant value.¶

MOQTSubgroupHeaderParsed = {
    stream_id: uint64
    track_alias: uint64
    group_id: uint64
    ? subgroup_id: uint64
    publisher_priority: uint8
    contains_end_of_group: bool
    extensions_present: bool

    * $$moqt-subgroupheaderparsed-extension
}

Figure 8: MOQTSubgroupHeaderParsed definition

4.8. subgroup_object_created

The subgroup_object_created event is emitted when a subgroup object is created. It has Core importance level.¶

MOQTSubgroupObjectCreated = {
    stream_id: uint64
    ? group_id: uint64
    ? subgroup_id: uint64
    object_id: uint64
    extension_headers_length: uint64
    ? extension_headers: [* MOQTExtensionHeader]
    object_payload_length: uint64
    ? object_status: uint64
    ? object_payload: RawInfo

    * $$moqt-subgroupobjectcreated-extension
}

Figure 9: MOQTSubgroupObjectCreated definition

4.9. subgroup_object_parsed

The subgroup_object_parsed event is emitted when a subgroup object is parsed. It has Core importance level.¶

MOQTSubgroupObjectParsed = {
    stream_id: uint64
    ? group_id: uint64
    ? subgroup_id: uint64
    object_id: uint64
    extension_headers_length: uint64
    ? extension_headers: [* MOQTExtensionHeader]
    object_payload_length: uint64
    ? object_status: uint64
    ? object_payload: RawInfo

    * $$moqt-subgroupobjectparsed-extension
}

Figure 10: MOQTSubgroupObjectParsed definition

4.10. fetch_header_created

The fetch_header_created event is emitted when a stream begins and a FETCH_HEADER is created. It has Core importance level.¶

MOQTFetchHeaderCreated = {
    stream_id: uint64
    request_id: uint64

    * $$moqt-fetchheadercreated-extension
}

Figure 11: MOQTFetchHeaderCreated definition

4.11. fetch_header_parsed

The fetch_header_parsed event is emitted when the SUBGROUP_HEADER is parsed. It has Core importance level.¶

MOQTFetchHeaderParsed = {
    stream_id: uint64
    request_id: uint64

    * $$moqt-fetchheaderparsed-extension
}

Figure 12: MOQTFetchHeaderParsed definition

4.12. fetch_object_created

The fetch_object_created event is emitted when a fetch object is created. It has Core importance level.¶

MOQTFetchObjectCreated = {
    stream_id: uint64
    group_id: uint64
    subgroup_id: uint64
    object_id: uint64
    publisher_priority: uint8
    extension_headers_length: uint64
    ? extension_headers: [* MOQTExtensionHeader]
    object_payload_length: uint64
    ? object_status: uint64
    ? object_payload: RawInfo

    * $$moqt-fetchobjectcreated-extension
}

Figure 13: MOQTFetchObjectCreated definition

4.13. fetch_object_parsed

The fetch_object_parsed event is emitted when a fetch object is parsed. It has Core importance level.¶

MOQTFetchObjectParsed = {
    stream_id: uint64
    group_id: uint64
    subgroup_id: uint64
    object_id: uint64
    publisher_priority: uint8
    extension_headers_length: uint64
    ? extension_headers: [* MOQTExtensionHeader]
    object_payload_length: uint64
    ? object_status: uint64
    ? object_payload: RawInfo

    * $$moqt-fetchobjectparsed-extension
}

Figure 14: MOQTFetchObjectParsed definition

4.14. data_stream_fin

The data_stream_fin event is emitted when a stream is closed with a FIN. The sender field describes who sent the FIN.¶

MOQTDataStreamFin = {
    stream_id: uint64
    sender: Owner

    * $$moqt-datastreamfin-extension
}

Figure 15: MOQTDataStreamFin definition

4.15. data_stream_reset

The data_stream_reset event is emitted when a stream is reset. The sender field describes who reset the stream.¶

MOQTDataStreamReset = {
    stream_id: uint64
    error_code: uint64
    sender: Owner

    * $$moqt-datastreamreset-extension
}

Figure 16: MOQTDataStreamReset definition

4.16. data_stream_stop_sending

The data_stream_stop_sending event is emitted when a STOP_SENDING is either sent or received on a stream. The sender field describes who sent the STOP_SENDING.¶

MOQTDataStreamStopSending = {
    stream_id: uint64
    error_code: uint64
    sender: Owner

    * $$moqt-datastreamstopsending-extension
}

Figure 17: MOQTDataStreamStopSending definition

5. MOQT Data Type Definitions

The following data type definitions can be used in MOQT events.¶

5.1. Owner

Owner = "local" /
        "remote"

Figure 18: Owner definition

5.2. MOQTLocation

A Location, as defined in Section 1.4.1 of [MOQT]¶

MOQTLocation = {
  group: uint64
  object: uint64
}

Figure 19: MOQTLocation definition

5.3. MOQTSubscriptionFilter

A Subscription Filter, as defined in Section 5.1.2 of [MOQT]¶

MOQTSubscriptionFilter = {
  filter_type: uint64
  ? start_location: MOQTLocation
  ? end_group: uint64
}

Figure 20: MOQTSubscriptionFilter definition

5.4. MOQTSetupParameter

The generic $MOQTSetupParameter is defined here as a CDDL "type socket" extension point. It can be extended to support additional MOQT Setup Parameters.¶

; The MOQTSetupParameter is any key-value map (e.g., JSON object)
$MOQTSetupParameter /= {
    * text => any
}

Figure 21: MOQTSetupParameter type socket definition

MOQTBaseSetupParameters /=  MOQTAuthoritySetupParameter /
                            MOQTPathSetupParameter /
                            MOQTMaxRequestIdSetupParameter /
                            MOQTMaxAuthTokenCacheSizeSetupParameter /
                            MOQTAuthorizationTokenSetupParameter /
                            MOQTImplementationSetupParameter /
                            MOQTUnknownSetupParameter

$MOQTSetupParameter /= MOQTBaseSetupParameters

Figure 22: MOQTBaseSetupParameters definition

5.4.1. MOQTAuthoritySetupParameter

MOQTAuthoritySetupParameter = {
  name: "authority"
  value: text
}

Figure 23: MOQTAuthoritySetupParameter definition

5.4.2. MOQTPathSetupParameter

MOQTPathSetupParameter = {
  name: "path"
  value: text
}

Figure 24: MOQTPathSetupParameter definition

5.4.3. MOQTMaxRequestIdSetupParameter

MOQTMaxRequestIdSetupParameter = {
  name: "max_request_id"
  value: uint64
}

Figure 25: MOQTMaxRequestIdSetupParameter definition

5.4.4. MOQTMaxAuthTokenCacheSizeSetupParameter

MOQTMaxAuthTokenCacheSizeSetupParameter = {
  name: "max_auth_token_cache_size"
  value: uint64
}

Figure 26: MOQTMaxAuthTokenCacheSizeSetupParameter definition

5.4.5. MOQTAuthorizationTokenSetupParameter

MOQTAuthorizationTokenSetupParameter = {
  name: "authorization_token"
  alias_type: $MOQTAliasType
  ? token_alias: uint64
  ? token_type: uint64
  ? token_value: RawInfo
}

$MOQTAliasType /=  "delete" /
                   "register" /
                   "use_alias" /
                   "use_value"

Figure 27: MOQTAuthorizationTokenSetupParameter definition

5.4.6. MOQTImplementationSetupParameter

MOQTImplementationSetupParameter = {
  name: "implementation"
  value: text
}

Figure 28: MOQTImplementationSetupParameter definition

5.4.7. MOQTUnknownSetupParameter

MOQTUnknownSetupParameter = {
  name:"unknown"
  name_bytes: uint64
  ? length: uint64
  ? value: uint64
  ? value_bytes: RawInfo
}

Figure 29: MOQTUnknownSetupParameter definition

5.5. MOQTParameter

The generic $MOQTParameter is defined here as a CDDL "type socket" extension point. It can be extended to support additional MOQT Parameters.¶

; The MOQTParameter is any key-value map (e.g., JSON object)
$MOQTParameter /= {
    * text => any
}

Figure 30: MOQTParameter type socket definition

MOQTBaseParameters /= MOQTAuthorizationTokenParameter /
                      MOQTDeliveryTimeoutParameter /
                      MOQTMaxCacheDurationParameter /
                      MOQTPublisherPriorityParameter /
                      MOQTSubscriberPriorityParameter /
                      MOQTGroupOrderParameter /
                      MOQTSubscriptionFilterParameter /
                      MOQTExpiresParameter /
                      MOQTLargestObjectParameter /
                      MOQTForwardParameter /
                      MOQTDynamicGroupsParameter /
                      MOQTNewGroupRequestParameter /
                      MOQTUnknownParameter

$MOQTParameter /= MOQTBaseParameters

Figure 31: MOQTBaseParameters definition

5.5.1. MOQTAuthorizationTokenParameter

MOQTAuthorizationTokenParameter = {
  name: "authorization_token"
  alias_type: uint64
  ? token_alias: uint64
  ? token_type: uint64
  ? token_value: RawInfo
}

Figure 32: MOQTAuthorizationTokenParameter definition

5.5.2. MOQTDeliveryTimeoutParameter

MOQTDeliveryTimeoutParameter = {
  name: "delivery_timeout"
  value: uint64
}

Figure 33: MOQTDeliveryTimeoutParameter definition

5.5.3. MOQTMaxCacheDurationParameter

MOQTMaxCacheDurationParameter = {
  name: "max_cache_duration"
  value: uint64
}

Figure 34: MOQTMaxCacheDurationParameter definition

5.5.4. MOQTPublisherPriorityParameter

MOQTPublisherPriorityParameter = {
  name: "publisher_priority"
  value: uint64
}

Figure 35: MOQTPublisherPriorityParameter definition

5.5.5. MOQTSubscriberPriorityParameter

MOQTSubscriberPriorityParameter = {
  name: "subscriber_priority"
  value: uint64
}

Figure 36: MOQTSubscriberPriorityParameter definition

5.5.6. MOQTGroupOrderParameter

MOQTGroupOrderParameter = {
  name: "group_order"
  value: uint64
}

Figure 37: MOQTGroupOrderParameter definition

5.5.7. MOQTSubscriptionFilterParameter

MOQTSubscriptionFilterParameter = {
  name: "subscription_filter"
  value: MOQTSubscriptionFilter
}

Figure 38: MOQTSubscriptionFilterParameter definition

5.5.8. MOQTExpiresParameter

MOQTExpiresParameter = {
  name: "expires"
  value: uint64
}

Figure 39: MOQTExpiresParameter definition

5.5.9. MOQTLargestObjectParameter

MOQTLargestObjectParameter = {
  name: "largest_object"
  value: MOQTLocation
}

Figure 40: MOQTLargestObjectParameter definition

5.5.10. MOQTForwardParameter

MOQTForwardParameter = {
  name: "forward"
  value: uint64
}

Figure 41: MOQTForwardParameter definition

5.5.11. MOQTDynamicGroupsParameter

MOQTDynamicGroupsParameter = {
  name: "dynamic_groups"
  value: uint64
}

Figure 42: MOQTDynamicGroupsParameter definition

5.5.12. MOQTNewGroupRequestParameter

MOQTNewGroupRequestParameter = {
  name: "new_group_request"
  value: uint64
}

Figure 43: MOQTNewGroupRequestParameter definition

5.5.13. MOQTUnknownParameter

MOQTUnknownParameter = {
  name:"unknown"
  name_bytes: uint64
  ? length: uint64
  ? value: uint64
  ? value_bytes: RawInfo
}

Figure 44: MOQTUnknownParameter definition

5.6. MOQTByteString

The MOQTByteString type allows representing MOQT bytestrings, such as the value of a Track or Track Namespace tuple field, using two different encodings. The value field can be used for bytestrings that can be encoded in UTF-8. The value_bytes field can be used for bytestrings of any type by using the hexstring encoding.¶

Implementations SHOULD populate one of either the value or value_bytes field. Populating both fields is redundant.¶

MOQTByteString = {
  ? value: text
  ? value_bytes: hexstring
}

Figure 45: MOQTByteString definition

5.7. MOQTControlMessage

The generic $MOQTControlMessage is defined here as a CDDL "type socket" extension point. It can be extended to support additional MOQT control message types.¶

; The MOQTControlMessage is any key-value map (e.g., JSON object)
$MOQTControlMessage /= {
    * text => any
}

Figure 46: MOQTControlMessage type socket definition

The MOQT control message types defined in this document are as follows:¶

MOQTBaseControlMessages = MOQTClientSetupMessage /
                          MOQTServerSetupMessage /
                          MOQTGoaway /
                          MOQTMaxRequestId /
                          MOQTRequestsBlocked /
                          MOQTRequestOk /
                          MOQTRequestError /
                          MOQTSubscribe /
                          MOQTSubscribeOk /
                          MOQTRequestUpdate /
                          MOQTUnsubscribe /
                          MOQTPublish /
                          MOQTPublishOk /
                          MOQTPublishDone /
                          MOQTFetch /
                          MOQTFetchOk /
                          MOQTFetchCancel /
                          MOQTTrackStatus /
                          MOQTPublishNamespace /
                          MOQTNamespace /
                          MOQTPublishNamespaceDone /
                          MOQTNamespaceDone /
                          MOQTPublishNamespaceCancel /
                          MOQTSubscribeNamespace

$MOQTControlMessage /= MOQTBaseControlMessages

Figure 47: MOQTBaseControlMessages definition

5.7.1. MOQTClientSetupMessage

MOQTClientSetupMessage = {
  type: "client_setup"
  number_of_parameters: uint64
  ? setup_parameters: [* $MOQTSetupParameter]
}

Figure 48: MOQTClientSetupMessage definition

5.7.2. MOQTServerSetupMessage

MOQTServerSetupMessage = {
  type: "server_setup"
  number_of_parameters: uint64
  ? setup_parameters: [* $MOQTSetupParameter]
}

Figure 49: MOQTServerSetupMessage definition

5.7.3. MOQTGoaway

MOQTGoaway = {
  type: "goaway"
  new_session_uri: RawInfo
}

Figure 50: MOQTGoaway definition

5.7.4. MOQTMaxRequestId

MOQTMaxRequestId = {
  type: "max_request_id"
  request_id: uint64
}

Figure 51: MOQTMaxRequestId definition

5.7.5. MOQTRequestsBlocked

MOQTRequestsBlocked = {
  type: "requests_blocked"
  maximum_request_id: uint64
}

Figure 52: MOQTRequestsBlocked definition

5.7.6. MOQTRequestOk

MOQTRequestOk = {
  type: "request_ok"
  request_id: uint64
  number_of_parameters: uint64
  ? parameters: [* $MOQTParameter]
}

Figure 53: MOQTRequestOk definition

5.7.7. MOQTRequestError

MOQTRequestError = {
  type: "request_error"
  request_id: uint64
  error_code: uint64
  retry_interval: uint64
  ? reason: text
  ? reason_bytes: hexstring
}

Figure 54: MOQTRequestError definition

5.7.8. MOQTSubscribe

5.7.9. MOQTSubscribeOk

MOQTSubscribeOk = {
  type: "subscribe_ok"
  request_id: uint64
  track_alias: uint64
  number_of_parameters: uint64
  ? parameters: [* $MOQTParameter]
  ? track_extensions: [* MOQTExtensionHeader]
}

Figure 56: MOQTSubscribeOk definition

5.7.10. MOQTRequestUpdate

MOQTRequestUpdate = {
  type: "request_update"
  request_id: uint64
  existing_request_id: uint64
  number_of_parameters: uint64
  ? parameters: [* $MOQTParameter]
}

Figure 57: MOQTRequestUpdate definition

5.7.11. MOQTUnsubscribe

MOQTUnsubscribe = {
  type: "unsubscribe"
  request_id: uint64
}

Figure 58: MOQTUnsubscribe definition

5.7.12. MOQTPublish

MOQTPublish = {
  type: "publish"
  request_id: uint64
  track_namespace: [ *MOQTByteString]
  track_name: MOQTByteString
  track_alias: uint64
  number_of_parameters: uint64
  ? parameters: [* $MOQTParameter]
  ? track_extensions: [* MOQTExtensionHeader]
}

Figure 59: MOQTPublish definition

5.7.13. MOQTPublishOk

MOQTPublishOk = {
  type: "publish_ok"
  request_id: uint64
  number_of_parameters: uint64
  ? parameters: [* $MOQTParameter]
}

Figure 60: MOQTPublishOk definition

5.7.14. MOQTPublishDone

MOQTPublishDone = {
  type: "publish_done"
  request_id: uint64
  status_code: uint64
  stream_count: uint64
  ? reason: text
  ? reason_bytes: hexstring
}

Figure 61: MOQTPublishDone definition

5.7.15. MOQTFetch

MOQTFetch = {
  type: "fetch"
  request_id: uint64
  fetch_type: $MOQTFetchType
  ? standalone_fetch: $MOQTStandaloneFetch
  ? joining_fetch: $MOQTJoiningFetch
  ? parameters: [* $MOQTParameter]
}

$MOQTStandaloneFetch = {
  track_namespace: [ *MOQTByteString]
  track_name: MOQTByteString
  start_location: MOQTLocation
  end_location: MOQTLocation
}

$MOQTJoiningFetch = {
  joining_request_id: uint64
  joining_start: uint64
}

$MOQTFetchType /=  "standalone" /
                   "absolute_joining" /
                   "relative_joining"

Figure 62: MOQTFetch definition

5.7.16. MOQTFetchOk

MOQTFetchOk = {
  type: "fetch_ok"
  request_id: uint64
  end_of_track: uint8
  end_location: MOQTLocation
  number_of_parameters: uint64
  ? parameters: [* $MOQTParameter]
  ? track_extensions: [* MOQTExtensionHeader]
}

Figure 63: MOQTFetchOk definition

5.7.17. MOQTFetchCancel

MOQTFetchCancel = {
  type: "fetch_cancel"
  request_id: uint64
}

Figure 64: MOQTFetchCancel definition

5.7.18. MOQTTrackStatus

MOQTTrackStatus = {
  type: "track_status"
  request_id: uint64
  track_namespace: [ *MOQTByteString]
  track_name: MOQTByteString
  number_of_parameters: uint64
  ? parameters: [* $MOQTParameter]
}

Figure 65: MOQTTrackStatus definition

5.7.19. MOQTPublishNamespace

MOQTPublishNamespace = {
  type: "publish_namespace"
  request_id: uint64
  track_namespace: [ *MOQTByteString]
  number_of_parameters: uint64
  ? parameters: [* $MOQTParameter]
}

Figure 66: MOQTPublishNamespace definition

5.7.20. MOQTNamespace

MOQTNamespace = {
  type: "namespace"
  track_namespace_suffix: [ *MOQTByteString]
}

Figure 67: MOQTNamespace definition

5.7.21. MOQTPublishNamespaceDone

MOQTPublishNamespaceDone = {
  type: "publish_namespace_done"
  request_id: uint64
}

Figure 68: MOQTPublishNamespaceDone definition

5.7.22. MOQTNamespaceDone

MOQTNamespaceDone = {
  type: "namespace_done"
  track_namespace_suffix: [ *MOQTByteString]
}

Figure 69: MOQTNamespaceDone definition

5.7.23. MOQTPublishNamespaceCancel

MOQTPublishNamespaceCancel = {
  type: "publish_namespace_cancel"
  track_namespace: [ *MOQTByteString]
  error_code: uint64
  ? reason: text
  ? reason_bytes: hexstring
}

Figure 70: MOQTPublishNamespaceCancel definition

5.7.24. MOQTSubscribeNamespace

MOQTSubscribeNamespace = {
  type: "subscribe_namespace"
  request_id: uint64
  track_namespace_prefix: [ *MOQTByteString]
  subscribe_options: $MOQTSubscribeOptions
  number_of_parameters: uint64
  ? parameters: [* $MOQTParameter]
}

$MOQTSubscribeOptions /=  "publish" /
                          "namespace" /
                          "both"

Figure 71: MOQTSubscribeNamespace definition

5.8. MOQTExtensionHeader

MOQTExtensionHeader = {
  header_type: uint64
  ? header_value: uint64
  ? header_length: uint64
  ? payload: RawInfo
}

Figure 72: Extension Header definition

6. Security Considerations

The security and privacy considerations discussed in [QLOG-MAIN] apply to this document as well.¶

7. IANA Considerations

This document registers a new entry in the "qlog event schema URIs" registry (created in Section 15 of [QLOG-MAIN]).¶

Event schema URI:: urn:ietf:params:qlog:events:moqt¶
Namespace: moqt¶
Event Types: control_message_created, control_message_parsed, stream_type_set, object_datagram_created, object_datagram_parsed, subgroup_header_created, subgroup_header_parsed, subgroup_object_created, subgroup_object_parsed, fetch_header_created, fetch_header_parsed, fetch_object_created, fetch_object_parsed¶
Description:: Event definitions related to the MOQT protocol.¶
Reference:: This Document¶

8. Normative References

[CDDL]: Birkholz, H., Vigano, C., and C. Bormann, "Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610, June 2019, <https://www.rfc-editor.org/rfc/rfc8610>.
[MOQT]: Nandakumar, S., Vasiliev, V., Swett, I., and A. Frindell, "Media over QUIC Transport", Work in Progress, Internet-Draft, draft-ietf-moq-transport-16, 13 January 2026, <https://datatracker.ietf.org/doc/html/draft-ietf-moq-transport-16>.
[QLOG-MAIN]: Marx, R., Niccolini, L., Seemann, M., and L. Pardue, "qlog: Structured Logging for Network Protocols", Work in Progress, Internet-Draft, draft-ietf-quic-qlog-main-schema-13, 20 October 2025, <https://datatracker.ietf.org/doc/html/draft-ietf-quic-qlog-main-schema-13>.
[QLOG-QUIC]: Marx, R., Niccolini, L., Seemann, M., and L. Pardue, "QUIC event definitions for qlog", Work in Progress, Internet-Draft, draft-ietf-quic-qlog-quic-events-12, 20 October 2025, <https://datatracker.ietf.org/doc/html/draft-ietf-quic-qlog-quic-events-12>.
[RFC2119]: Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC8174]: Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

Acknowledgments

Thanks to Lorenzo Miniero, Sujay Patel, and Aman Sharm for feedback and contributions to this document.¶

Authors' Addresses

Lucas Pardue

Cloudflare

Email: lucas@lucaspardue.com

Mathis Engelbart

Technical University of Munich

Email: mathis.engelbart@gmail.com

Aman Sharma