| Internet-Draft | HTTP/2 qlog event definitions | March 2026 |
| Pardue | Expires 3 September 2026 | [Page] |
This document defines a qlog event schema containing concrete events for the core HTTP/2 protocol and selected extensions.¶
This note is to be removed before publishing as an RFC.¶
The latest revision of this draft can be found at https://LPardue.github.io/draft-pardue-httpbis-qlog-h2-events/draft-pardue-httpbis-qlog-h2-events.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-pardue-httpbis-qlog-h2-events/.¶
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This document defines a qlog event schema (Section 8 of [QLOG-MAIN]) containing concrete events for the core HTTP/2 protocol [HTTP/2] and selected extensions ([ALTSVC], [ORIGIN], [EXTENDED-CONNECT] and [EXTENSIBLE_PRIORITIZATION]).¶
The event namespace with identifier http2 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.¶
| Name value | Importance | Definition |
|---|---|---|
| http2:parameters_set | Core | Section 4.1 |
| http2:parameters_restored | Core | Section 4.2 |
| http2:frame_created | Core | Section 4.3 |
| http2:frame_parsed | Core | Section 4.4 |
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.¶
This document describes how HTTP/2 is expressed in qlog with an event schema.
Per the requirements in Section 8 of [QLOG-MAIN], this document registers the
http2 namespace. The event schema URI is urn:ietf:params:qlog:events:http2.¶
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:http2. 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:http2-99.¶
The namespace identifier itself is not affected by this requirement.¶
HTTP/2 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 $$ CDDL "group socket" syntax, as also
described in [QLOG-MAIN].¶
HTTP2EventData = HTTP2ParametersSet /
HTTP2ParametersRestored /
HTTP2FrameCreated /
HTTP2FrameParsed
$ProtocolEventData /= HTTP2EventData
The parameters_set event contains HTTP/2 settings, mostly those received from
the SETTINGS frame. It has Core importance level.¶
Parameters are typically set once but they can be set at different times during
the connection, therefore a qlog can have multiple instances of parameters_set
with different fields set.¶
The "initiator" field reflects how Settings are exchanged on a connection. Sent settings have the value "local" and received settings have the value "received".¶
HTTP2ParametersSet = {
? initiator: Initiator
? header_table_size: uint32
? enable_push: uint32
? max_concurrent_streams: uint32
? initial_window_size: uint32
? max_frame_size: uint32
? max_header_list_size: uint32
? extended_connect: uint32
? no_rfc7540_priorities: uint32
* $$http2-parametersset-extension
}
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.¶
When using TLS 0-RTT, HTTP/2 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/2 settings were restored and to which values when
utilizing 0-RTT. It has Core importance level.¶
HTTP2ParametersRestored = {
? initiator: Initiator
? header_table_size: uint32
? enable_push: uint32
? max_concurrent_streams: uint32
? initial_window_size: uint32
? max_frame_size: uint32
? max_header_list_size: uint32
? extended_connect: uint32
? no_rfc7540_priorities: uint32
* $$http2-parametersrestored-extension
}
The frame_created event is emitted when the HTTP/2 framing actually happens.
It has Core importance level.¶
HTTP2FrameCreated = {
stream_id: uint32
frame: $HTTP2Frame
* $$http2-framecreated-extension
}
The frame_parsed event is emitted when the HTTP/2 frame is parsed. It has Core
importance level.¶
HTTP2FrameParsed = {
stream_id: uint32
frame: $HTTP2Frame
* $$http2-frameparsed-extension
}
The following data type definitions can be used in HTTP/2 events.¶
Initiator = "local" /
"remote"
The generic $HTTP2Frame is defined here as a CDDL "type socket" extension point.
It can be extended to support additional HTTP/2 frame types.¶
; The HTTP2Frame is any key-value map (e.g., JSON object)
$HTTP2Frame /= {
* text => any
}
The HTTP/2 frame types defined in this document are as follows:¶
HTTP2BaseFrames = HTTP2DataFrame /
HTTP2HeadersFrame /
HTTP2PriorityFrame /
HTTP2RstStreamFrame /
HTTP2SettingsFrame /
HTTP2PushPromiseFrame /
HTTP2PingFrame /
HTTP2GoawayFrame /
HTTP2WindowUpdateFrame /
HTTP2ContinuationFrame /
HTTP2UnknownFrame
HTTP2ExtensionFrames = HTTP2AltSvcFrame /
HTTP2OriginFrame /
HTTP2PriorityUpdateFrame
$HTTP2Frame /= HTTP2BaseFrames / HTTP2ExtensionFrames
HTTP2DataFrame = {
frame_type: "data"
? padded: bool .default false
? end_stream: bool .default false
? raw: RawInfo
}
The payload of an HTTP/2 HEADERS frame is the HPACK-encoding of an HTTP field
section; see [RFC7541]. HTTP2HeadersFrame, in contrast, contains the HTTP
field section without encoding.¶
HTTP2HTTPField = {
? name: text
? name_bytes: hexstring
? value: text
? value_bytes: hexstring
}
HTTP2HeadersFrame = {
frame_type: "headers"
? priority: bool .default false
? padded: bool .default false
? end_headers: bool .default false
? end_stream: bool .default false
headers: [* HTTP2HTTPField]
? raw: RawInfo
}
For example, the HTTP field section¶
:path: /index.html :method: GET :authority: example.org :scheme: https¶
would be represented in a JSON serialization as:¶
headers: [
{
"name": ":path",
"value": "/"
},
{
"name": ":method",
"value": "GET"
},
{
"name": ":authority",
"value": "example.org"
},
{
"name": ":scheme",
"value": "https"
}
]
[HTTP/2] and Section 5.1 of [HTTP] define rules for the
characters used in HTTP field sections names and values. Characters outside the
range are invalid and result in the message being treated as malformed. It can
however be useful to also log these invalid HTTP fields. Characters in the
allowed range can be safely logged by the text type used in the name and
value fields of HTTP2HTTPField. Characters outside the range are unsafe for the
text type and need to be logged using the name_bytes and value_bytes field.
An instance of HTTP2HTTPField MUST include either the name or name_bytes
field and MAY include both. An HTTP2HTTPField MAY include a value or
value_bytes field or neither.¶
HTTP2PriorityFrame = {
frame_type: "priority"
exclusive: bool .default false
stream_dependency: uint32
weight: uint8
? raw: RawInfo
}
HTTP2RstStreamFrame = {
frame_type: "rst_stream"
error_code: uint32
? raw: RawInfo
}
The settings field can contain zero or more entries. Each setting has a name field, which corresponds to Setting Name as defined (or as would be defined if registered) in the "HTTP/3 Settings" registry maintained at https://www.iana.org/assignments/HTTP2-parameters.¶
An endpoint that receives unknown settings is not able to log a specific name.
Instead, the name value of "unknown" can be used and the value captured in the
name_bytes field; a numerical value without variable-length integer encoding.¶
HTTP2SettingsFrame = {
frame_type: "settings"
? ack: bool .default false
settings: [* HTTP2Setting]
? raw: RawInfo
}
HTTP2Setting = {
? name: $HTTP2SettingsName
; only when name === "unknown"
? name_bytes: uint32
value: uint32
}
$HTTP2SettingsName /= "settings_header_table_size" /
"settings_enable_push" /
"settings_max_concurrent_streams" /
"settings_initial_window_size" /
"settings_max_frame_size" /
"settings_max_header_list_size" /
"settings_extended_connect" /
"settings_no_rfc7540_priorities" /
"unknown"
HTTP2PushPromiseFrame = {
frame_type: "push_promise"
? padded: bool .default false
? end_headers: bool .default false
promised_stream_id: uint32
headers: [* HTTP2HTTPField]
? raw: RawInfo
}
HTTP2PingFrame = {
frame_type: "ping"
? ack: bool .default false
opaque_data: hexstring
? raw: RawInfo
}
HTTP2GoawayFrame = {
frame_type: "goaway"
last_stream_id: uint32
error_code: uint32
? additional_debug_data: hexstring
? raw: RawInfo
}
HTTP2WindowUpdateFrame = {
frame_type: "window_update"
window_size_increment: uint32
? raw: RawInfo
}
HTTP2ContinuationFrame = {
frame_type: "continuation"
? end_headers: bool .default false
headers: [* HTTP2HTTPField]
? raw: RawInfo
}
The frame_type_bytes field is the numerical value without variable-length integer encoding.¶
HTTP2UnknownFrame = {
frame_type: "unknown"
frame_type_bytes: uint32
? raw: RawInfo
}
The ALTSVC frame is defined in [ALTSVC].¶
HTTP2AltSvcFrame = {
frame_type: "altsvc"
origin_len: uint16
? origin: text
? alt-svc-field-value: text
? raw: RawInfo
}
The ORIGIN frame is defined in [ORIGIN].¶
HTTP2OriginEntry = {
origin_len: uint16
? ASCII-Origin: text
}
HTTP2OriginFrame = {
frame_type: "origin"
origin_entries: [* HTTP2OriginEntry]
? raw: RawInfo
}
The PRIORITY_UPDATE frame is defined in [EXTENSIBLE_PRIORITIZATION].¶
HTTP2PriorityUpdateFrame = {
frame_type: "priority_update"
prioritized_stream_id: uint32
priority_field_value: HTTP2Priority
? raw: RawInfo
}
; The priority value in ASCII text, encoded using Structured Fields
; Example: u=5, i
HTTP2Priority = text
The security and privacy considerations discussed in Section 14 of [QLOG-MAIN] apply to this document as well.¶
This document will have IANA actions if adopted.¶
TODO acknowledge.¶