Compression Dictionary Transport
draft-ietf-httpbis-compression-dictionary-19

[Ballot discuss]
** How to best cite living specifications?

  [FETCH]    WHATWG, "Fetch - Living Standard", June 2024,
              .
  [URLPattern]
              WHATWG, "URL Pattern - Living Standard", March 2024,
              .

Realizing that these are living specifications, I don’t understand how the above citations are providing stable references.  How does one get the “March 2024 version” of “URL Pattern”?  Is there a specific GitHub commit reference that can be used instead?

[Ballot comment]
Thank you to Reese Enghardt for the GENART review.

** Section 4.  This section provides normative guidance that relies on [SHARED-BROTLI]. 

-- As such, [SHARED-BROTLI] needs to be a normative reference. 

-- Is the WG confident that this reference has sufficient stability/review for use?  I ask because [SHARED-BROTLI] appears to be an expired, individual I-D.

** Section 4 and 5.  Both of these sections specify a fixed size header (36-bytes and 40 bytes) that includes a SHA-256 hash. 
Is this document the authoritative source for defining these headers?  If so, is it expected that this SHA-256 hash would provide imbue any security properties?  I ask because the use of SHA-256 is hard coded and there is no means for algorithm agility.

[Ballot comment]
# Gunter Van de Velde, RTG AD, comments for draft-ietf-httpbis-compression-dictionary-12

## Many thanks for writing this document. I found the text not easy to process, mostly because i am not  overly familiar with http compression technologies, and a significant number of abbreviations and acronyms sounded exotic to me. However I do suspect that is normal and that these all of these are understood by the HTTP experts.

## I only got one small suggestion about making the abstract. Feel fre to use or ignore:

11 Abstract
12
13   This specification defines a mechanism for using designated HTTP
14   responses as an external dictionary for future HTTP responses for
15   compression schemes that support using external dictionaries (e.g.,
16   Brotli (RFC 7932) and Zstandard (RFC 8878)).

[minor]
Making the abstract slightly higher level to explain the benefits of the document.

"
This document specifies a mechanism for dictionary-based compression in the Hypertext Transfer Protocol (HTTP). The proposed method enables the use of pre-shared dictionaries to improve compression efficiency for HTTP responses. By utilizing this technique, clients and servers can reduce the size of transmitted data, leading to improved performance and reduced bandwidth consumption. This document extends existing HTTP compression methods and provides guidelines for the negotiation and use of compression dictionaries within the HTTP protocol.
"

[Ballot comment]
# Orie Steele, ART AD, comments for draft-ietf-httpbis-compression-dictionary-12
CC @OR13

* line numbers:
  - https://author-tools.ietf.org/api/idnits?url=https://www.ietf.org/archive/id/draft-ietf-httpbis-compression-dictionary-12.txt&submitcheck=True

* comment syntax:
  - https://github.com/mnot/ietf-comments/blob/main/format.md

* "Handling Ballot Positions":
  - https://ietf.org/about/groups/iesg/statements/handling-ballot-positions/

## Comment

### String

```
220   This document uses the following terminology from Section 3 of
221   [STRUCTURED-FIELDS] to specify syntax and parsing: Dictionary,
222   String, Inner List, Token, and Byte Sequence.
```

Consider the following examples: https://url.spec.whatwg.org/#example-5434421b

Am I correct to assume that the matcher would be written against the percent encoded pathname?

For example:

```
var url = new URL("♞", new URL("https://chess.example/"))
```

```
...
Use-As-Dictionary: match="/%E2%99%9E"
```

I think query or "search" as it is referred to in URL Pattern would be handled the same way, for example:

```
new URL("http://www.example.com/düsseldorf?neighbourhood=Lörick")
```

```
...
Use-As-Dictionary: match="/d%C3%BCsseldorf?neighbourhood=L%C3%B6rick"
```

String, is defined in https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-sfbis-06#section-3.3.3

But given that URL Pattern matches against https://url.spec.whatwg.org/#concept-url

A few complete examples covering interesting unicode cases would improve the document.

[Ballot comment]
Thank you for writing this (and helping me understand it :-))

I have two comments:

1: I found:
"4.  If PATTERN has regexp groups then return FALSE."
confusing -- I initially understood this to be regex capturing groups (e.g "I like cheese" -> /.*(c.*se)/ captures 'cheese'). After discussions with Patrick I see that this is actually https://urlpattern.spec.whatwg.org/#dom-urlpattern-hasregexpgroups ...

2: I also found the number of 'dictionary's in "The "match" value is required and MUST be included in the Use-As-Dictionary Dictionary for the dictionary to be considered valid." hard to parse, and I couldn't figure out if the second "Dictionary" should actually have been "dictionary" (is it a [STRUCTURED-FIELDS] term or just a word :-))

[Ballot comment]

# Éric Vyncke, INT AD, comments for draft-ietf-httpbis-compression-dictionary-09

Thank you for the work put into this document. Please note that I am outside my area of expertise when reading this document.

Please find below some non-blocking COMMENT points (but replies would be appreciated even if only for my own education), and some nits.

Special thanks to Mark Nottingham for the shepherd's detailed write-up including the WG consensus and the justification of the intended status.

I hope that this review helps to improve the document,

Regards,

-éric


# COMMENTS (non-blocking)

## Introduction

Suggest adding some (graphical?) explanations on how the technique works. It took me a while (admitting that I am not familiar with the domain) to understand how the headers are used. In other words, it would be nice to present the forest before describing the trees.

## Section 1

Is it "file" or "page/resource" in `Using a previous version of a file as a dictionary for a newer version ` ?

## Section 2.1.3

It is unclear to me how `when the dictionary is advertised as being available` can be verified by the client.

## Section 2.3

I have hard time to fit the example with `The "Dictionary-ID" request header ... MUST be identical to the server-provided "id".` as there is a prefix: `/v1/main.js`. This is of course due to structured field, but it would be nice to explain the structure of this field.

## Section 4

As draft-vandevenne-shared-brotli-format has expired for more than a year (and not even WG adopted), I wonder whether this section is still useful ? I.e., just keep section 5 and remove section 4.

Is there a reason why the lengths of the magic number are different for the two supported compressions ?

## Section 7.1

Suggest referring to the IANA registry by their URI (i.e., https://www.iana.org/assignments/http-parameters/http-parameters.xhtml#content-coding) rather than by the RFC that has created them.

## Section 8

Should `middle-boxes` be more descriptive (e.g., web proxies, ...) ?

# NITS (non-blocking / cosmetic)

## Section 2.1.4

Suggest to use double quotes around raw in `and defaults to raw`.

## Section 4

s/fixed 4 byte sequence and a 32 byte hash/fixed 4-byte sequence and a 32-byte hash/ ?

s/Bytes/bytes/ ?

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

IANA has completed its review of draft-ietf-httpbis-compression-dictionary-09. If any part of this review is inaccurate, please let us know.

IANA understands that, upon approval of this document, there are three actions which we must complete.

First, in the HTTP Content Coding Registry in the Hypertext Transfer Protocol (HTTP) Parameters registry group located at:

https://www.iana.org/assignments/http-parameters/

two new registrations will be made as follows:

Name: dcb
Description: "Dictionary-Compressed Brotli" data format.
Reference: [ RFC-to-be ]
Notes: Section 4

Name: dcz
Description: "Dictionary-Compressed Zstandard" data format.
Reference: [ RFC-to-be ]
Notes: Section 5

Second, in the Hypertext Transfer Protocol (HTTP) Field Name Registry located at:

https://www.iana.org/assignments/http-fields/

three new field names are to be registered as follows:

Field Name: Use-As-Dictionary
Template:
Status: permanent
Structured Type:
Reference: [ RFC-to-be; Section 2.1 ]
Comments:

Field Name: Available-Dictionary
Template:
Status: permanent
Structured Type:
Reference: [ RFC-to-be; Section 2.2 ]
Comments:

Field Name: Dictionary-ID
Template:
Status: permanent
Structured Type:
Reference: [ RFC-to-be; Section 2.3 ]
Comments:

As this document requests registrations in an Expert Review or Specification Required (see RFC 8126) registry, we have initiated and completed the required Expert Review via a separate request.

Third, in the Link Relation Types registry in the Link Relations registry group located at:

https://www.iana.org/assignments/link-relations/

a single new registration is to be made as follows:

Relation Name: compression-dictionary
Description: Refers to a compression dictionary used for content encoding.
Reference: [ RFC-to-be ]
Notes:

As this also requests a registration in an Expert Review or Specification Required (see RFC 8126) registry, we have initiated and completed the required Expert Review via a separate request.

We understand that these are the only actions required to be completed upon approval of this document.

NOTE: The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is meant only to confirm the list of actions that will be performed.

For definitions of IANA review states, please see:

https://datatracker.ietf.org/help/state/draft/iana-review

Thank you,

David Dong
IANA Services Sr. Specialist

The following Last Call announcement was sent out (ends 2024-08-06):

From: The IESG
To: IETF-Announce
CC: draft-ietf-httpbis-compression-dictionary@ietf.org, francesca.palombini@ericsson.com, httpbis-chairs@ietf.org, ietf-http-wg@w3.org, mnot@mnot.net
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Compression Dictionary Transport) to Proposed Standard


The IESG has received a request from the HTTP WG (httpbis) to consider the
following document: - 'Compression Dictionary Transport'
  as Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
last-call@ietf.org mailing lists by 2024-08-06. Exceptionally, comments may
be sent to iesg@ietf.org instead. In either case, please retain the beginning
of the Subject line to allow automated sorting.

Abstract


  This specification defines a mechanism for using designated HTTP
  responses as an external dictionary for future HTTP responses for
  compression schemes that support using external dictionaries (e.g.,
  Brotli (RFC 7932) and Zstandard (RFC 8878)).




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-httpbis-compression-dictionary/



No IPR declarations have been submitted directly on this I-D.

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?

_Fairly broad agreement._

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

_There was some discussion of how many compression algorithms to include. Although there were diverse opinions, we converged on the approach taken in the draft._

3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize the areas of conflict in separate email messages to the
  responsible Area Director. (It should be in a separate email because this
  questionnaire is publicly available.)

_No._

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?

_Yes; Chrome has implemented on the client side, and several parties have indicated interest and/or intent to implement on the server side._

## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.

_Yes; there are browser-specific implementation considerations that have been coordinated with the W3C and WHATWG._

6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

*Routine HTTP-related registry reviews need to happen as part of IETF LC; no issues anticipated.*

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] for syntax and
  formatting validation? If there are any resulting errors or warnings, what is
  the justification for not fixing them at this time? Does the YANG module
  comply with the Network Management Datastore Architecture (NMDA) as specified
  in [RFC 8342][5]?

_No YANG here._

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

*HTTP structured fields syntax have been checked with a linter.*


## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?

_Yes._

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

_N/A._

11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

_Proposed Standard. This is appropriate for a new protocol specification with some implementation._

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.

_Yes; they have been reminded._

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.

_Yes._

14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)

See discussion of downreferences.

15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

RFC5861 can be made informative.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?

_N/A._

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

RFC5861 is a downwards reference, but can be made informative.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?

_No._

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

_No._

20. Describe the document shepherd's review of the IANA considerations section,
    especially with regard to its consistency with the body of the document.
    Confirm that all aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

_The requests appear to be correct._

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.

_N/A._


[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://wiki.ietf.org/group/ops/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://wiki.ietf.org/group/iesg/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/

# Document Shepherd Write-Up for Group Documents

*This version is dated 4 July 2022.*

Thank you for your service as a document shepherd. Among the responsibilities is
answering the questions in this write-up to give helpful context to Last Call
and Internet Engineering Steering Group ([IESG][1]) reviewers, and your
diligence in completing it is appreciated. The full role of the shepherd is
further described in [RFC 4858][2]. You will need the cooperation of the authors
and editors to complete these checks.

Note that some numbered items contain multiple related questions; please be sure
to answer all of them.

## Document History

1. Does the working group (WG) consensus represent the strong concurrence of a
  few individuals, with others being silent, or did it reach broad agreement?

_Fairly broad agreement._

2. Was there controversy about particular points, or were there decisions where
  the consensus was particularly rough?

_There was some discussion of how many compression algorithms to include. Although there were diverse opinions, we converged on the approach taken in the draft._

3. Has anyone threatened an appeal or otherwise indicated extreme discontent? If
  so, please summarize the areas of conflict in separate email messages to the
  responsible Area Director. (It should be in a separate email because this
  questionnaire is publicly available.)

_No._

4. For protocol documents, are there existing implementations of the contents of
  the document? Have a significant number of potential implementers indicated
  plans to implement? Are any existing implementations reported somewhere,
  either in the document itself (as [RFC 7942][3] recommends) or elsewhere
  (where)?

_Yes; Chrome has implemented on the client side, and several parties have indicated interest and/or intent to implement on the server side._

## Additional Reviews

5. Do the contents of this document closely interact with technologies in other
  IETF working groups or external organizations, and would it therefore benefit
  from their review? Have those reviews occurred? If yes, describe which
  reviews took place.

_Yes; there are browser-specific implementation considerations that have been coordinated with the W3C and WHATWG._

6. Describe how the document meets any required formal expert review criteria,
  such as the MIB Doctor, YANG Doctor, media type, and URI type reviews.

*Routine HTTP-related registry reviews need to happen as part of IETF LC; no issues anticipated.*

7. If the document contains a YANG module, has the final version of the module
  been checked with any of the [recommended validation tools][4] for syntax and
  formatting validation? If there are any resulting errors or warnings, what is
  the justification for not fixing them at this time? Does the YANG module
  comply with the Network Management Datastore Architecture (NMDA) as specified
  in [RFC 8342][5]?

_No YANG here._

8. Describe reviews and automated checks performed to validate sections of the
  final version of the document written in a formal language, such as XML code,
  BNF rules, MIB definitions, CBOR's CDDL, etc.

*HTTP structured fields syntax have been checked with a linter.*


## Document Shepherd Checks

9. Based on the shepherd's review of the document, is it their opinion that this
  document is needed, clearly written, complete, correctly designed, and ready
  to be handed off to the responsible Area Director?

_Yes._

10. Several IETF Areas have assembled [lists of common issues that their
    reviewers encounter][6]. For which areas have such issues been identified
    and addressed? For which does this still need to happen in subsequent
    reviews?

_N/A._

11. What type of RFC publication is being requested on the IETF stream ([Best
    Current Practice][12], [Proposed Standard, Internet Standard][13],
    [Informational, Experimental or Historic][14])? Why is this the proper type
    of RFC? Do all Datatracker state attributes correctly reflect this intent?

_Proposed Standard. This is appropriate for a new protocol specification with some implementation._

12. Have reasonable efforts been made to remind all authors of the intellectual
    property rights (IPR) disclosure obligations described in [BCP 79][7]? To
    the best of your knowledge, have all required disclosures been filed? If
    not, explain why. If yes, summarize any relevant discussion, including links
    to publicly-available messages when applicable.

_Yes; they have been reminded._

13. Has each author, editor, and contributor shown their willingness to be
    listed as such? If the total number of authors and editors on the front page
    is greater than five, please provide a justification.

_Yes._

14. Document any remaining I-D nits in this document. Simply running the [idnits
    tool][8] is not enough; please review the ["Content Guidelines" on
    authors.ietf.org][15]. (Also note that the current idnits tool generates
    some incorrect warnings; a rewrite is underway.)

See discussion of downreferences.

15. Should any informative references be normative or vice-versa? See the [IESG
    Statement on Normative and Informative References][16].

RFC5861 can be made informative.

16. List any normative references that are not freely available to anyone. Did
    the community have sufficient access to review any such normative
    references?

_N/A._

17. Are there any normative downward references (see [RFC 3967][9] and [BCP
    97][10]) that are not already listed in the [DOWNREF registry][17]? If so,
    list them.

RFC5861 is a downwards reference, but can be made informative.

18. Are there normative references to documents that are not ready to be
    submitted to the IESG for publication or are otherwise in an unclear state?
    If so, what is the plan for their completion?

_No._

19. Will publication of this document change the status of any existing RFCs? If
    so, does the Datatracker metadata correctly reflect this and are those RFCs
    listed on the title page, in the abstract, and discussed in the
    introduction? If not, explain why and point to the part of the document
    where the relationship of this document to these other RFCs is discussed.

_No._

20. Describe the document shepherd's review of the IANA considerations section,
    especially with regard to its consistency with the body of the document.
    Confirm that all aspects of the document requiring IANA assignments are
    associated with the appropriate reservations in IANA registries. Confirm
    that any referenced IANA registries have been clearly identified. Confirm
    that each newly created IANA registry specifies its initial contents,
    allocations procedures, and a reasonable name (see [RFC 8126][11]).

_The requests appear to be correct._

21. List any new IANA registries that require Designated Expert Review for
    future allocations. Are the instructions to the Designated Expert clear?
    Please include suggestions of designated experts, if appropriate.

_N/A._


[1]: https://www.ietf.org/about/groups/iesg/
[2]: https://www.rfc-editor.org/rfc/rfc4858.html
[3]: https://www.rfc-editor.org/rfc/rfc7942.html
[4]: https://wiki.ietf.org/group/ops/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://wiki.ietf.org/group/iesg/ExpertTopics
[7]: https://www.rfc-editor.org/info/bcp79
[8]: https://www.ietf.org/tools/idnits/
[9]: https://www.rfc-editor.org/rfc/rfc3967.html
[10]: https://www.rfc-editor.org/info/bcp97
[11]: https://www.rfc-editor.org/rfc/rfc8126.html
[12]: https://www.rfc-editor.org/rfc/rfc2026.html#section-5
[13]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.1
[14]: https://www.rfc-editor.org/rfc/rfc2026.html#section-4.2
[15]: https://authors.ietf.org/en/content-guidelines-overview
[16]: https://www.ietf.org/about/groups/iesg/statements/normative-informative-references/
[17]: https://datatracker.ietf.org/doc/downref/