Zstandard Compression and the 'application/zstd' Media Type
draft-kucherawy-rfc8478bis-06

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

The IANA Functions Operator has completed its review of draft-kucherawy-rfc8478bis-06. If any part of this review is inaccurate, please let us know.

IANA understands that the actions in the IANA considerations section of this document have been completed. Prior to publication as a RFC, the references for these actions should change from draft-kucherawy-rfc8478bis-05 to draft-kucherawy-rfc8478bis-06.

Upon approval as a RFC those same references will be changed to [ RFC-to-be ].

The IANA Functions Operator understands that these are the only action 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.

Thank you,

Sabrina Tanamal
Senior IANA Services Specialist

The following Last Call announcement was sent out (ends 2021-01-19):

From: The IESG
To: IETF-Announce
CC: Subodh Iyengar , barryleiba@gmail.com, draft-kucherawy-rfc8478bis@ietf.org, subodh@fb.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Zstandard Compression and the application/zstd Media Type) to Informational RFC


The subject document: - 'Zstandard Compression and the application/zstd Media
Type'
  went through last call in January 2020
at revision -03, was approved by the IESG in April at revision -05, and went to
the RFC Editor at that time.  During final editing (AUTH48), a new errata report
(6303) was filed on RFC 8478, and the document authors and responsible AD
agreed that it was important to incorporate a fix for that errata report in this
update.

The fix is in revision -06, and affects Section 3.1.1.5.  You can see the diffs here:
https://www.ietf.org/rfcdiff?url2=draft-kucherawy-rfc8478bis-06
We are making an additional IETF Last Call on this version so that the community
can review and comment on these late changes.  After completion of this Last
Call, we expect to return the document to the RFC Editor so that they may
complete their editing and publish this version as an Informational RFC.

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 2021-01-19. 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

  Zstandard, or "zstd" (pronounced "zee standard"), is a data
  compression mechanism.  This document describes the mechanism and
  registers a media type and content encoding to be used when
  transporting zstd-compressed content via Multipurpose Internet Mail
  Extensions (MIME).  It also registers a corresponding media type,
  content encoding, and structured syntax suffix.

  Despite use of the word "standard" as part of its name, readers are
  advised that this document is not an Internet Standards Track
  specification; it is being published for informational purposes only.

  This document replaces and obsoletes RFC 8478.


The file can be obtained via
https://datatracker.ietf.org/doc/draft-kucherawy-rfc8478bis/

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

[Ballot comment]
Thank you for the work put into this document. And, I like the fact that the authors put in evidence in the abstract that it is NOT a standard document from the IETF. Albeit I wonder why this document is not requested to be pubslished as a standard.

Due to too many documents for this telechat (and one week of vacations to be honest...), I am balloting "No objection" trusting the ballots of my IESG colleagues/friends. I only quickly browsed the document with my internet area glasses.

Nevertheless, please find below some non-blocking COMMENTs  and NITS.

I hope that this helps to improve the document,

Regards,

-éric

== DISCUSS ==


== COMMENTS ==

-- Section 3.1.1 --
May I suggest to use the wording "0 or 4 bytes" rather than "0-4 bytes" for the Content_Checksum? The former hints to have a variable length between 0 and 4 bytes long.

-- Section 3.1.1.1. --
To be honest (possibly because of my quick browse), I fail to understand why the frame header has a minimum size of 2 bytes while all fields are optional except for the 1-byte Frame_Header_Descriptor ?


== NITS ==

A couple of nits, like in section 3.1.1.3.1.1. where the values 00, 10, ... should be identified as binary values.

[Ballot comment]
Please respond to the secdir review.

The guidance in Section 3.1.1.2.3 (of RFC 8478; now Section 3.1.1.2.4 of
the -03) to send a Raw Block if compression would result in exceeding
the maximum size seems like it might be worth retaining.

[I did a fairly thorough review of what became RFC 8478, so here I
mostly just look at the diff.]

Section 1

  This document describes the Zstandard format.  Also, to enable the
  transport of a data object compressed with Zstandard, this document
  registers a media type that can be used to identify such content when
  it is used in a payload encoded using Multipurpose Internet Mail
  Extensions (MIME).

It also registers a media-type structured syntax suffix.

Section 6

It's a little weird to have a "Section 6 -- Use of Dictionaries" and a
"Section 7.4 --Dictionaries" that have fairly related content.

  Provisioning for use of dictionaries with zstd is planned for future
  work.  To ensure compatibility with the future specification of use

Is this planned to involve widely-distributed and well-known
dictionaries, or a more localized provisioning process (or both)?  It
might be worth clarifying.

Section 7

I'd consider "has updated the reference field for two previously
existing registrations and made one new registration".

Section 9

Are there additional implementations that are worth mentioning now that
almost a couple years have passed?

Acknowledgments

It may be worth retaining the acknowledgments from RFC 8478 with a note
of their provenance, given how little has changed since then.

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

The IANA Functions Operator has completed its review of draft-kucherawy-rfc8478bis-03. If any part of this review is inaccurate, please let us know.

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

First, in the application registry on the Media Types registry page located at:

https://www.iana.org/assignments/media-types/

the existing registration for:

zstd

will have its reference changed to [ RFC-to-be ].

Second, in the HTTP Content Coding Registry on the Hypertext Transfer Protocol (HTTP) Parameters registry page located at:

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

the existing registration for:

zstd (A stream of bytes compressed using the Zstandard protocol)

will have its reference changed to [ RFC-to-be ].

Third, in the Structured Syntax Suffix Registry located at:

https://www.iana.org/assignments/media-type-structured-suffix/

a single, new registration will be made as follows:

Name: Zstandard
+suffix: +zstd
References: [ RFC-to-be ]
Encoding Considerations: binary
Interoperability Considerations:
Fragment Identifier Considerations: The syntax and semantics of fragment identifiers specified for +zstd should be as specified for "application/zstd".
Security Considerations: [ RFC-to-be; Section 7 ]
Contact: [ RFC-to-be; Section 7 ]
Author/Change Controller: [ RFC-to-be; Section 7 ]
Registration Date: [ TBD-at-Registration ]
Modification Date:

As this document requests registrations in an Expert Review or Specification Required (see RFC 8126) registry, we will initiate the required Expert Review via a separate request. This review must be completed before the document's IANA state can be changed to "IANA OK."

The IANA Functions Operator understands 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.

Thank you,

Sabrina Tanamal
Senior IANA Services Specialist

The following Last Call announcement was sent out (ends 2020-01-17):

From: The IESG
To: IETF-Announce
CC: Subodh Iyengar , draft-kucherawy-rfc8478bis@ietf.org, subodh@fb.com, barryleiba@gmail.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (Zstandard Compression and the application/zstd Media Type) to Informational RFC


The IESG has received a request from an individual submitter to consider the
following document: - 'Zstandard Compression and the application/zstd Media
Type'
  as Informational RFC

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 2020-01-17. 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


  Zstandard, or "zstd" (pronounced "zee standard"), is a data
  compression mechanism.  This document describes the mechanism and
  registers a media type and content encoding to be used when
  transporting zstd-compressed content via Multipurpose Internet Mail
  Extensions (MIME).

  Despite use of the word "standard" as part of its name, readers are
  advised that this document is not an Internet Standards Track
  specification; it is being published for informational purposes only.

  This document replaces and obsoletes RFC 8478.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-kucherawy-rfc8478bis/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-kucherawy-rfc8478bis/ballot/


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

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet
Standard, Informational, Experimental, or Historic)? Why is this the
proper type of RFC? Is this type of RFC indicated in the title page
header?

Informational. This is an update to an existing informational RFC. The
RFC type is on the title page header.

(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections: 

Technical Summary 
---------
Zstandard, or "zstd" (pronounced "zee standard"), is a data
compression mechanism.  This document describes the mechanism and
registers a media type and content encoding to be used when
transporting zstd-compressed content via Multipurpose Internet Mail
Extensions (MIME).

Despite use of the word "standard" as part of its name, readers are
advised that this document is not an Internet Standards Track
specification; it is being published for informational purposes only.

Working Group Summary 
---------
This is not the product of a working group.

Document Quality
---------
This protocol is widely implemented already. See section 9 of this
document.

Thorough review was done for RFC 8478. This is an update containing a
small number of minor corrections, mostly in errata reports.

One of the co-authors is a media type reviewer. No other formal reviews
are necessary.

Personnel
---------
Subodh Iyengar is the Document Shepherd.
Barry Leiba is the Responsible Area Director.

(3) Briefly describe the review of this document that was performed by
the Document Shepherd. If this version of the document is not ready for
publication, please explain why the document is being forwarded to the
IESG.

The document contains clarifications that have come to light since RFC
8478. The document fixes certain normative constraints in RFC 8478 that
were never implemented, so that future implementors don't try to
implement them.  These are all minor changes.

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

No.

(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that took
place.

No. Authors believe that the changes do not impact security in any
meaningful way.

(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the IESG
should be aware of? For example, perhaps he or she is uncomfortable with
certain parts of the document, or has concerns whether there really is a
need for it. In any event, if the interested community has discussed
those issues and has indicated that it still wishes to advance the
document, detail those concerns here.

I have no specific concerns.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

Yes.

(8) Has an IPR disclosure been filed that references this document? If
so, summarize any discussion and conclusion regarding the IPR
disclosures.

None.

(9) How solid is the consensus of the interested community behind this
document? Does it represent the strong concurrence of a few individuals,
with others being silent, or does the interested community as a whole
understand and agree with it? 

No current implementor has voiced any conerns about this change.

(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise 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

(11) Identify any ID nits the Document Shepherd has found in this
document. (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough. 

The id-nits run is clean.

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

There are no formal reviews required for compression. One author is a
media type reviewer. The media type suffix registration has a typo by
referring to the wrong section for security considerations.

(13) Have all references within this document been identified as either
normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

No new references have been added since RFC 8478.

(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in the
Last Call procedure.

No.

(16) Will publication of this document change the status of any existing
RFCs? Are those RFCs listed on the title page header, listed in the
abstract, and discussed in the introduction? If the RFCs are not listed
in the Abstract and Introduction, explain why, and point to the part of
the document where the relationship of this document to the other RFCs is
discussed. If this information is not in the document, explain why the
interested community considers it unnecessary.

This document updates RFC 8478. The title page does not call out this
update explicitly and should.

(17) 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 protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly identified.
Confirm that newly created IANA registries include a detailed
specification of the initial contents for the registry, that allocations
procedures for future registrations are defined, and a reasonable name
for the new registry has been suggested (see RFC 8126).

The IANA considerations section appears to be correct and complete.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find useful
in selecting the IANA Experts for these new registries.

No new registries are being created.

(19) Describe reviews and automated checks performed by to validate
sections of the document written in a formal language, such as XML code,
BNF rules, MIB definitions, YANG modules, etc.

No formal languages are used.

(20) If the document contains a YANG module, has the module been checked
with any of the recommended validation tools
(https://trac.ietf.org/trac/ops/wiki/yang-review-tools) 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 RFC8342?

No YANG modules are defined is in this document.

(1) What type of RFC is being requested (BCP, Proposed Standard, Internet Standard, Informational, Experimental, or Historic)? Why is this the proper type of RFC? Is this type of RFC indicated in the title page header? 

Informational. This is an update to an existing informational RFC. The RFC type is on the title page header.



(2) The IESG approval announcement includes a Document Announcement Write-Up. Please provide such a Document Announcement Write-Up. Recent examples can be found in the "Action" announcements for approved documents. The approval announcement contains the following sections: 


Technical Summary 
Zstandard, or "zstd" (pronounced "zee standard"), is a data
compression mechanism.  This document describes the mechanism and
registers a media type and content encoding to be used when
transporting zstd-compressed content via Multipurpose Internet Mail
Extensions (MIME).

Despite use of the word "standard" as part of its name, readers are
advised that this document is not an Internet Standards Track
specification; it is being published for informational purposes only.

Working Group Summary 


This is not the product of a working group.


Document Quality 



Are there existing implementations of the protocol? Have a significant number of vendors indicated their plan to implement the specification?

This protocol is widely implemented already. See section 9 of this document


Are there any reviewers that merit special mention as having done a thorough review, e.g., one that resulted in important changes or a conclusion that the document had no substantive issues? 



Thorough review was done for RFC 8478. This is an update containing a small number of minor corrections.



If there was a MIB Doctor, YANG Doctor, Media Type or other expert review, what was its course (briefly)? 



One of the co-authors is a media type reviewer. No other formal reviews are necessary.


Personnel
Who is the Document Shepherd?
Subodh Iyengar

Who is the Responsible Area Director?
Barry Liba

(3) Briefly describe the review of this document that was performed by the Document Shepherd. If this version of the document is not ready for publication, please explain why the document is being forwarded to the IESG.


The document contains clarifications that have come to light since RFC 8478. The document fixes certain normative constraints in RFC 8478 which were never implemented by implementations in order to prevent future implementations from implementing them.  Therefore I believe that these are minor changes. 



(4) Does the document Shepherd have any concerns about the depth or breadth of the reviews that have been performed? 

No.



(5) Do portions of the document need review from a particular or from broader perspective, e.g., security, operational complexity, AAA, DNS, DHCP, XML, or internationalization? If so, describe the review that took place. 



No. Authors believe that the changes do not impact security in any meaningful way.



(6) Describe any specific concerns or issues that the Document Shepherd has with this document that the Responsible Area Director and/or the IESG should be aware of? For example, perhaps he or she is uncomfortable with certain parts of the document, or has concerns whether there really is a need for it. In any event, if the interested community has discussed those issues and has indicated that it still wishes to advance the document, detail those concerns here. 



I have no specific concerns. 



(7) Has each author confirmed that any and all appropriate IPR disclosures required for full conformance with the provisions of BCP 78 and BCP 79 have already been filed. If not, explain why. 



Yes.



(8) Has an IPR disclosure been filed that references this document? If so, summarize any discussion and conclusion regarding the IPR disclosures. 

None.



(9) How solid is the consensus of the interested community behind this document? Does it represent the strong concurrence of a few individuals, with others being silent, or does the interested community as a whole understand and agree with it? 


No current implementor has voiced any conerns about this change.



(10) Has anyone threatened an appeal or otherwise indicated extreme discontent? If so, please summarise 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



(11) Identify any ID nits the Document Shepherd has found in this document. (See http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist). Boilerplate checks are not enough; this check needs to be thorough. 


The id-nits run is clean.



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



There are no formal reviews required for compression. One author is a media type reviewer. The media type suffix registration has a typo by referring to the wrong section for security considerations.



(13) Have all references within this document been identified as either normative or informative? 



Yes.



(14) Are there normative references to documents that are not ready for advancement or are otherwise in an unclear state? If such normative references exist, what is the plan for their completion? 



No new references have been added since RFC 8478.



(15) Are there downward normative references references (see RFC 3967)? If so, list these downward references to support the Area Director in the Last Call procedure. 



No.



(16) Will publication of this document change the status of any existing RFCs? Are those RFCs listed on the title page header, listed in the abstract, and discussed in the introduction? If the RFCs are not listed in the Abstract and Introduction, explain why, and point to the part of the document where the relationship of this document to the other RFCs is discussed. If this information is not in the document, explain why the interested community considers it unnecessary. 



No. This document updates RFC 8478. The title page does not call out this update explicitly and should.



(17) 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 protocol extensions that the document makes are associated with the appropriate reservations in IANA registries. Confirm that any referenced IANA registries have been clearly identified. Confirm that newly created IANA registries include a detailed specification of the initial contents for the registry, that allocations procedures for future registrations are defined, and a reasonable name for the new registry has been suggested (see RFC 8126). 



The IANA considerations section appears to be correct and complete.



(18) List any new IANA registries that require Expert Review for future allocations. Provide any public guidance that the IESG would find useful in selecting the IANA Experts for these new registries. 



No new registries are being created.





(19) Describe reviews and automated checks performed by to validate sections of the document written in a formal language, such as XML code, BNF rules, MIB definitions, YANG modules, etc.


No formal languages are used.



(20) If the document contains a YANG module, has the module been checked with any of the recommended validation tools (https://trac.ietf.org/trac/ops/wiki/yang-review-tools) 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 RFC8342?


No YANG modules are defined is in this document.


A document shepherd needs to be assigned, and a shepherd writeup needs to be recorded.

This should be very straightforward, as this is just revising RFC 8478 with one important errata report and one important clarification.