HTTP/3 qlog event definitions

1.1. Notational Conventions

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, category, type, data, group_id, protocol_type, importance, RawInfo, and time-related fields.¶

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.¶

2.1. 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 HTTP/3 connection. 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).¶

4.1. parameters_set

The parameters_set event contains HTTP/3 and QPACK-level settings, mostly those received from the HTTP/3 SETTINGS frame. It has Base importance level; see Section 9.2 of [QLOG-MAIN].¶

All these parameters are typically set once and never change. However, they might be set at different times during the connection, therefore a qlog can have multiple instances of parameters_set with different fields set.¶

The "owner" field reflects how Settings are exchanged on a connection. Sent settings have the value "local" and received settings have the value "received".¶

As a reminder the CDDL unwrap operator (~), see [RFC8610]), copies the fields from the referenced type (H3Parameters) into the target type directly, extending the target with the unwrapped fields.¶

H3ParametersSet = {
    ? owner: Owner
    ~H3Parameters

    ; qlog-specific
    ; indicates whether this implementation waits for a SETTINGS
    ; frame before processing requests
    ? waits_for_settings: bool
}

H3Parameters = {
    ; RFC9114
    ? max_field_section_size: uint64

    ; RFC9204
    ? max_table_capacity: uint64
    ? blocked_streams_count: uint64

    ; RFC9220 (SETTINGS_ENABLE_CONNECT_PROTOCOL)
    ? extended_connect: uint16

    ; RFC9297 (SETTINGS_H3_DATAGRAM)
    ? h3_datagram: uint16

    ; additional settings for grease and extensions
    * text => uint64
}

The parameters_set event can contain any number of unspecified fields. This allows for representation of reserved settings (aka GREASE) or ad-hoc support for extension settings that do not have a related qlog schema definition.¶

4.2. parameters_restored

When using QUIC 0-RTT, HTTP/3 clients are expected to remember and reuse the server's SETTINGs from the previous connection. The parameters_restored event is used to indicate which HTTP/3 settings were restored and to which values when utilizing 0-RTT. It has Base importance level; see Section 9.2 of [QLOG-MAIN].¶

H3ParametersRestored = {
    ~H3Parameters
}

The parameters_restored event can contain any number of unspecified fields. This allows for representation of reserved settings (aka GREASE) or ad-hoc support for extension settings that do not have a related qlog schema definition.¶

4.3. stream_type_set

The stream_type_set event conveys when a HTTP/3 stream type becomes known; see Sections 6.1 and 6.2 of [HTTP/3]. It has Base importance level; see Section 9.2 of [QLOG-MAIN].¶

Client bidirectional streams always have a stream_type value of "request". Server bidirectional streams have no defined use, although extensions could change that.¶

Unidirectional streams in either direction begin with with a variable-length integer type. Where the type is not known, the stream_type value of "unknown" type can be used and the value captured in the stream_type_value field; a numerical value without variable-length integer encoding.¶

H3StreamTypeSet = {
    ? owner: Owner
    stream_id: uint64
    stream_type: H3StreamType

    ; only when stream_type === "unknown"
    ? stream_type_value: uint64

    ; only when stream_type === "push"
    ? associated_push_id: uint64
}

H3StreamType =  "request" /
                  "control" /
                  "push" /
                  "reserved" /
                  "unknown" /
                  "qpack_encode" /
                  "qpack_decode"

4.4. priority_updated

Emitted when the priority of a request stream or push stream is initialized or updated through mechanisms defined in [RFC9218]. For example, the priority can be updated through signals received from client and/or server (e.g., in HTTP/3 HEADERS or PRIORITY_UPDATE frames) or it can be changed or overridden due to local policies. The event has Base importance level; see Section 9.2 of [QLOG-MAIN].¶

H3PriorityUpdated = {
    ; if the prioritized element is a request stream
    ? stream_id: uint64

    ; if the prioritized element is a push stream
    ? push_id: uint64

    ? old: H3Priority
    new: H3Priority
}

4.5. frame_created

The frame_created event is emitted when the HTTP/3 framing actually happens. It has Core importance level; see Section 9.2 of [QLOG-MAIN].¶

This event does not necessarily coincide with HTTP/3 data getting passed to the QUIC layer. For that, see the stream_data_moved event in [QLOG-QUIC].¶

H3FrameCreated = {
    stream_id: uint64
    ? length: uint64
    frame: $H3Frame
    ? raw: RawInfo
}

4.6. frame_parsed

The frame_parsed event is emitted when the HTTP/3 frame is parsed. It has Core importance level; see Section 9.2 of [QLOG-MAIN].¶

This event is not necessarily the same as when the HTTP/3 data is actually received on the QUIC layer. For that, see the stream_data_moved event in [QLOG-QUIC].¶

H3FrameParsed = {
    stream_id: uint64
    ? length: uint64
    frame: $H3Frame
    ? raw: RawInfo
}

HTTP/3 DATA frames can have arbitrarily large lengths to reduce frame header overhead. As such, DATA frames can span multiple QUIC packets. In this case, the frame_parsed event is emitted once for the frame header, and further streamed data is indicated using the stream_data_moved event.¶

4.7. datagram_created

The datagram_created event is emitted when an HTTP/3 Datagram is created (see [RFC9297]). It has Base importance level; see Section 9.2 of [QLOG-MAIN].¶

This event does not necessarily coincide with the HTTP/3 Datagram getting passed to the QUIC layer. For that, see the datagram_data_moved event in [QLOG-QUIC].¶

H3DatagramCreated = {
    quarter_stream_id: uint64
    ? datagram: $H3Datagram
    ? raw: RawInfo
}

4.8. datagram_parsed

The datagram_parsed event is emitted when the HTTP/3 Datagram is parsed (see [RFC9297]). It has Base importance level; see Section 9.2 of [QLOG-MAIN].¶

This event is not necessarily the same as when the HTTP/3 Datagram is actually received on the QUIC layer. For that, see the datagram_data_moved event in [QLOG-QUIC].¶

H3DatagramParsed = {
    quarter_stream_id: uint64
    ? datagram: $H3Datagram
    ? raw: RawInfo
}

4.9. push_resolved

The push_resolved event is emitted when a pushed resource (Section 4.6 of [HTTP/3]) is successfully claimed (used) or, conversely, abandoned (rejected) by the application on top of HTTP/3 (e.g., the web browser). This event provides additional context that can is aid debugging issues related to server push. It has Extra importance level; see Section 9.2 of [QLOG-MAIN].¶

H3PushResolved = {
    ? push_id: uint64

    ; in case this is logged from a place that does not have access
    ; to the push_id
    ? stream_id: uint64
    decision: H3PushDecision
}

H3PushDecision = "claimed" /
                   "abandoned"

5.1. Owner

Owner = "local" /
        "remote"

5.2. H3Frame

The generic $H3Frame is defined here as a CDDL extension point (a "socket" or "plug"). It can be extended to support additional HTTP/3 frame types.¶

; The H3Frame is any key-value map (e.g., JSON object)
$H3Frame /= {
    * text => any
}

The HTTP/3 frame types defined in this document are as follows:¶

H3BaseFrames = H3DataFrame /
               H3HeadersFrame /
               H3CancelPushFrame /
               H3SettingsFrame /
               H3PushPromiseFrame /
               H3GoawayFrame /
               H3MaxPushIDFrame /
               H3ReservedFrame /
               H3UnknownFrame

$H3Frame /= H3BaseFrames

5.3. H3Datagram

The generic $H3Datagram is defined here as a CDDL extension point (a "socket" or "plug"). It can be extended to support additional HTTP/3 datagram types. This document intentionally does not define any specific HTTP/3 Datagram types.¶

; The H3Datagram is any key-value map (e.g., JSON object)
$H3Datagram /= {
    * text => any
}

H3DataFrame = {
    frame_type: "data"
    ? raw: RawInfo
}

headers: [
  {
    "name": ":path",
    "value": "/"
  },
  {
    "name": ":method",
    "value": "GET"
  },
  {
    "name": ":authority",
    "value": "127.0.0.1:4433"
  },
  {
    "name": ":scheme",
    "value": "https"
  }
]

H3HeadersFrame = {
    frame_type: "headers"
    headers: [* H3HTTPField]
}

H3HTTPField = {
    name: text
    ? value: text
}

H3CancelPushFrame = {
    frame_type: "cancel_push"
    push_id: uint64
}

H3SettingsFrame = {
    frame_type: "settings"
    settings: [* H3Setting]
}

H3Setting = {
    name: text
    value: uint64
}

H3PushPromiseFrame = {
    frame_type: "push_promise"
    push_id: uint64
    headers: [* H3HTTPField]
}

H3GoawayFrame = {
    frame_type: "goaway"

    ; Either stream_id or push_id.
    ; This is implicit from the sender of the frame
    id: uint64
}

H3MaxPushIDFrame = {
    frame_type: "max_push_id"
    push_id: uint64
}

H3PriorityUpdateFrame = {
    frame_type: "priority_update"

    ; if the prioritized element is a request stream
    ? stream_id: uint64

    ; if the prioritized element is a push stream
    ? push_id: uint64

    priority_field_value: H3Priority
}

; The priority value in ASCII text, encoded using Structured Fields
; Example: u=5, i
H3Priority = text

H3ReservedFrame = {
    frame_type: "reserved"
    ? length: uint64
}

H3UnknownFrame = {
    frame_type: "unknown"
    frame_type_value: uint64
    ? raw: RawInfo
}

H3ApplicationError = "http_no_error" /
                       "http_general_protocol_error" /
                       "http_internal_error" /
                       "http_stream_creation_error" /
                       "http_closed_critical_stream" /
                       "http_frame_unexpected" /
                       "http_frame_error" /
                       "http_excessive_load" /
                       "http_id_error" /
                       "http_settings_error" /
                       "http_missing_settings" /
                       "http_request_rejected" /
                       "http_request_cancelled" /
                       "http_request_incomplete" /
                       "http_early_response" /
                       "http_connect_error" /
                       "http_version_fallback"

; ensure HTTP errors are properly validate in QUIC events as well
; e.g., QUIC's ConnectionClose Frame
$ApplicationError /= H3ApplicationError

Since draft-ietf-quic-qlog-h3-events-06:

• ProtocolEventBody is now called ProtocolEventData (#352)¶

• Editorial changes (#402)¶

Since draft-ietf-quic-qlog-h3-events-05:

• Removed all qpack event definitions (#335)¶

• Various editorial changes¶

Since draft-ietf-quic-qlog-h3-events-04:

• Renamed 'http' category to 'h3' (#300)¶

• H3HTTPField.value is now optional (#296)¶

• Added definitions for RFC9297 (HTTP/3 Datagram extension) (#310)¶

• Added definitions for RFC9218 (HTTP Extensible Prioritizations extension) (#312)¶

• Added definitions for RFC9220 (Extended Connect extension) (#325)¶

• Editorial and formatting changes (#298, #258, #299, #304, #327)¶

Since draft-ietf-quic-qlog-h3-events-03:

• Ensured consistent use of RawInfo to indicate raw wire bytes (#243)¶

• Changed HTTPStreamTypeSet:raw_stream_type to stream_type_value (#54)¶

• Changed HTTPUnknownFrame:raw_frame_type to frame_type_value (#54)¶

• Renamed max_header_list_size to max_field_section_size (#282)¶

Since draft-ietf-quic-qlog-h3-events-02:

• Renamed HTTPStreamType data to request (#222)¶

• Added HTTPStreamType value unknown (#227)¶

• Added HTTPUnknownFrame (#224)¶

• Replaced old and new fields with stream_type in HTTPStreamTypeSet (#240)¶

• Changed HTTPFrame to a CDDL plug type (#257)¶

• Moved data definitions out of the appendix into separate sections¶

• Added overview Table of Contents¶

Since draft-ietf-quic-qlog-h3-events-01:

• No changes - new draft to prevent expiration¶

Since draft-ietf-quic-qlog-h3-events-00:

• Change the data definition language from TypeScript to CDDL (#143)¶

Since draft-marx-qlog-event-definitions-quic-h3-02:

• These changes were done in preparation of the adoption of the drafts by the QUIC working group (#137)¶

• Split QUIC and HTTP/3 events into two separate documents¶

• Moved RawInfo, Importance, Generic events and Simulation events to the main schema document.¶

Since draft-marx-qlog-event-definitions-quic-h3-01:

Major changes:¶

• Moved data_moved from http to transport. Also made the "from" and "to" fields flexible strings instead of an enum (#111,#65)¶

• Moved packet_type fields to PacketHeader. Moved packet_size field out of PacketHeader to RawInfo:length (#40)¶

• Made events that need to log packet_type and packet_number use a header field instead of logging these fields individually¶

• Added support for logging retry, stateless reset and initial tokens (#94,#86,#117)¶

• Moved separate general event categories into a single category "generic" (#47)¶

• Added "transport:connection_closed" event (#43,#85,#78,#49)¶

• Added version_information and alpn_information events (#85,#75,#28)¶

• Added parameters_restored events to help clarify 0-RTT behaviour (#88)¶

Smaller changes:¶

• Merged loss_timer events into one loss_timer_updated event¶

• Field data types are now strongly defined (#10,#39,#36,#115)¶

• Renamed qpack instruction_received and instruction_sent to instruction_created and instruction_parsed (#114)¶

• Updated qpack:dynamic_table_updated.update_type. It now has the value "inserted" instead of "added" (#113)¶

• Updated qpack:dynamic_table_updated. It now has an "owner" field to differentiate encoder vs decoder state (#112)¶

• Removed push_allowed from http:parameters_set (#110)¶

• Removed explicit trigger field indications from events, since this was moved to be a generic property of the "data" field (#80)¶

• Updated transport:connection_id_updated to be more in line with other similar events. Also dropped importance from Core to Base (#45)¶

• Added length property to PaddingFrame (#34)¶

• Added packet_number field to transport:frames_processed (#74)¶

• Added a way to generically log packet header flags (first 8 bits) to PacketHeader¶

• Added additional guidance on which events to log in which situations (#53)¶

• Added "simulation:scenario" event to help indicate simulation details¶

• Added "packets_acked" event (#107)¶

• Added "datagram_ids" to the datagram_X and packet_X events to allow tracking of coalesced QUIC packets (#91)¶

• Extended connection_state_updated with more fine-grained states (#49)¶

Since draft-marx-qlog-event-definitions-quic-h3-00:

• Event and category names are now all lowercase¶

• Added many new events and their definitions¶

• "type" fields have been made more specific (especially important for PacketType fields, which are now called packet_type instead of type)¶

• Events are given an importance indicator (issue #22)¶

• Event names are more consistent and use past tense (issue #21)¶

• Triggers have been redefined as properties of the "data" field and updated for most events (issue #23)¶