The Deprecation HTTP Header Field
draft-ietf-httpapi-deprecation-header-09

[Ballot comment]
My only concern is how this might appear different to an enduser, and whether and enduser could be tricked into thinking this "redirect" is more authoritative then it really is (eg coming from an attacker), with a target Link: being used to modify the behaviour of the potential victims.

[Ballot comment]
# Orie Steele, ART AD, comments for draft-ietf-httpapi-deprecation-header-08
CC @OR13

* line numbers:
  - https://author-tools.ietf.org/api/idnits?url=https://www.ietf.org/archive/id/draft-ietf-httpapi-deprecation-header-08.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/


## Comments

Thanks to Julian Reschke for the ARTART Review.

### MUST Sunset use a different data format for date?

```
260   date is Sunday, June 30, 2024 at 23:59:59 UTC.  Please note that for
261   historical reasons the Sunset HTTP header field uses a different data
262   format for date.
```

Is this a normative requirement? This could be made clearer.

### SHOULDs in Security Considerations

```
313   Resource documentation SHOULD provide additional information about
314   the deprecation, such as including recommendation(s) for replacement.
315   Applications consuming the resource SHOULD check the referred
316   resource documentation to verify authenticity and accuracy.  In cases
```

```
323   Therefore, applications consuming the resource SHOULD, if possible,
324   consult the resource developer to discuss potential impact due to
325   deprecation and plan for possible transition to a recommended
326   resource(s).
```

Both of these seem like guidance to human operators, not guidance for ensuring implementation interoperability.

Consider dropping the BCP14 language, or explain when it can be ignored.

I see Robert Sparks had similar comments on -06 on the list.

[Ballot comment]
While not an HTTP expert, I find this document both easy to read and useful. Some comments though:

# Actual consumer of this header ?

Only in section 3.1 there is a hint that the actual consumer of the Deprecation header is the application developer, all the previous text is about the 'application' (and I wonder how can an application use this header). Should the abstract/introduction be more explicit ?

# Section 2.2

How can the scope be signalled to the consumer ? It does not seem that it is via the Deprecation header, if not via the Deprecation header, then I suggest to move section 2.2 out of section 2, which is about the Deprecation header.

# Section 4

I wonder why `for historical reasons the Sunset HTTP header field uses a different data format for date`, doesn't make it more complex for application to parse ? Or is it just for some compression ?

# Affiliation

Is there any reason why authors have no cited affiliations ? We all know that IETF authors/editors only represent themselves and not their employers (if any).

[Ballot comment]
Section 1, paragraph 2
>    The act of deprecation does not change any behavior of the resource.
>    It informs client applications of the fact that a resource will be or
>    is deprecated.  The Deprecation HTTP response header field can be
>    used to convey this information at runtime indicating when the
>    deprecation will be in effect.

First of all thanks to Julian Reschke for providing the GENART review. Secondly, the draft is short and easy to read. Thanks for that.

I tend to agree with Julian that there is redundant text in this document that can be gotten ridden of. The second sentence in this paragraph is a perfect example of it. The same is the case with the paragraph under Section 2.

Section 4, paragraph 2
>    The timestamp given in the Sunset header field MUST NOT be earlier
>    than the one given in the Deprecation header field.

Just like Gunter, I am also curious about what happens if the Sunset header field is earlier than the Deprecation header field.

Section 7, paragraph 2
>    Resource documentation SHOULD provide additional information about
>    the deprecation, such as including recommendation(s) for replacement.
>    Applications consuming the resource SHOULD check the referred
>    resource documentation to verify authenticity and accuracy.  In cases
>    where a Link header field is used to provide documentation, one
>    should assume (unless served over HTTPS) that the content of the Link
>    header field may not be secure, private or integrity-guaranteed, and
>    due caution should be exercised when using it.  Also, in cases where
>    the Deprecation header field value is a date in the future, it can
>    lead to information that otherwise might not be available.
>    Therefore, applications consuming the resource SHOULD, if possible,
>    consult the resource developer to discuss potential impact due to
>    deprecation and plan for possible transition to a recommended
>    resource(s).

It was not clear to me why having the Deprecation header field value in the future might lead to information that otherwise may not be available. First of all, what "information" are we talking about? If it is the link, can't that happen when the link is not available regardless of whether it is in the past or the future?

No reference entries found for these items, which were mentioned in the text:
[draft-ietf-regext-rdap-jscontact]. Instead of providing a link, you should be using [I-D.ietf-regext-rdap-jscontact] as a reference.

DOWNREF [RFC8594] from this Proposed Standard to Informational RFC8594. (For
IESG discussion. It seems this DOWNREF was not mentioned in the Last Call and
also seems to not appear in the DOWNREF registry.)

Found terminology that should be reviewed for inclusivity; see
https://www.rfc-editor.org/part2/#inclusive_language for background and more
guidance:

* Term "master"; alternatives might be "active", "central", "initiator",
  "leader", "main", "orchestrator", "parent", "primary", "server"

[Ballot comment]
# Gunter Van de Velde, RTG AD, comments for draft-ietf-httpapi-deprecation-header-08.txt

# I am not so familiar with HTTP technologies, however i found that this draft was well written and interesting to read. Thank you for writing this text.

# Please find the following non-blocking comments that crossed my mind when reading the draft. Please use the comments at your discretion.

#GENERIC COMMENTS
#================
## the word "Deprecation" (uppercase D) and "deprecation" (lowercase d) is used mixed within the document. Not sure if that is the intent?


#DETAILED COMMENTS
#=================
##classified as [minor] and [major]

10 Abstract
11
12   The Deprecation HTTP response header field is used to signal to
13   consumers of a resource (in the sense of URI) that the resource will
14   be or has been deprecated.  Additionally, the deprecation link
15   relation can be used to link to a resource that provides additional
16   information about planned or existing deprecation, and possibly ways
17   in which client applications can best manage deprecation.

[minor]
Would the following proposed abstract for a higher level description of what is documented in the draft.

"
This document defines a new HTTP response header field, "Deprecation", that allows a server to signal to clients that an API or resource is deprecated. The header field provides additional information, including the date of deprecation and an optional link to documentation. The "Deprecation" header field is intended to inform clients about the lifecycle of an API or resource, allowing them to adapt their usage accordingly. This document also outlines best practices for using the "Deprecation" header in HTTP responses.
"

67 Table of Contents
68
69   1.  Introduction
70     1.1.  Notational Conventions
71   2.  The Deprecation HTTP Response Header Field

[minor]
Most of the drafts that i review have a page count in the table of content.
I find that easy to go to certain text. Is there a reason why this table is different?

255   The timestamp given in the Sunset header field MUST NOT be earlier
256   than the one given in the Deprecation header field.

[minor]
What happens if the sunset would be earlier as the Deprecation timestamp?
both are ignored or the deprecation is ignored s it is only a timestamp indication/hint?

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

IANA has completed its review of draft-ietf-httpapi-deprecation-header-06. If any part of this review is inaccurate, please let us know.

We have a question about one of the actions requested in the IANA Considerations section of this document.

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

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

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

A single new registration will be made as follows:

Field Name: Deprecation
Status: Standard
Structured Type:
Template:
Reference: [ RFC-to-be; Section 2 ]
Comments:

As this document requests registrations in an Expert Review or Specification Required (see RFC 8126) registry, we have initiated 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.”

Second, in the Link Relation Types registry located at:

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

A single new registration will be made as follows:

Relation Name: deprecation
Description:
Reference: [ RFC-to-be ]
Notes:

IANA Question --> What should the “description” for this link relation type be?

As this also requests registrations in an Expert Review or Specification Required (see RFC 8126) registry, we have initiated 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.”

We understand that these two actions are the only ones 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 2024-09-06):

From: The IESG
To: IETF-Announce
CC: draft-ietf-httpapi-deprecation-header@ietf.org, francesca.palombini@ericsson.com, httpapi-chairs@ietf.org, httpapi@ietf.org, rsalz@akamai.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (The Deprecation HTTP Header Field) to Proposed Standard


The IESG has received a request from the Building Blocks for HTTP APIs WG
(httpapi) to consider the following document: - 'The Deprecation HTTP Header
Field'
  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 2024-09-06. 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


  The Deprecation HTTP response header field is used to signal to
  consumers of a resource (in the sense of URI) that the resource will
  be or has been deprecated.  Additionally, the deprecation link
  relation can be used to link to a resource that provides additional
  information about planned or existing deprecation, and possibly ways
  in which clients can best manage deprecation.




The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-httpapi-deprecation-header/



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?

It had broad, although at times shallow, consensus. Nobody was ever really opposed.
This is typical of the HTTPAPI WG, which has a mix of people who are interested
in different aspects of HTTP API's.

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

Earlier in the draft history, there was a suggestion that this concept is really
part of a larger lifecycle for APIs. After a couple of months nobody stepped
forward to work on such a document, and the Chairs decided (backed by no
opposition from the WG membership) to proceed with "just" deprecation.

There was also a (relatively) large amount of discussion around one
particular issue, https://github.com/ietf-wg-httpapi/deprecation-header/issues/11
The Chairs determined rough consensus for the authors's proposed resolution.

>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, neither.

>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)?

The draft lists several implementations in Appendix A, including other IETF work at
https://tools.ietf.org/html/draft-loffredo-regext-rdap-jcard-deprecation

Implementations and questions have been discussed on many websites, including StackOverflow,
the Python library GitHub, and a nice blog post (at https://imhoratiu.wordpress.com/2021/01/20/respectful-rest-apis-sunset-and-deprecation-http-headers/)
which compare header with Sunset (RFC 8594)

## 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.

There is membership overlap with HTTPBIS WG, which is the obvious place to
collaborate and it has been done informally.

>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.

None needed.

>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]?

n/a

>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.

n/a

## 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?

ART (now WIT).  No issues.

>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?

standards track and that makes sense since it defines a new HTTP header field.

>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.  No IPR claims.

>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, both of them want to be listed as authors.

>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.)

Nothing important. One missing reference to the RFC for URI.

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

There's a down ref question in the nits output which we would like guidance on.
Other then that, all seems fine.

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

None.

>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.

The doc references "SFBIS" draft, so this should probably be put in the same
cluster as that.  See https://datatracker.ietf.org/doc/draft-ietf-httpbis-sfbis/

>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?

Just the one; see prev question.

>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 changes.

>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]).

There are no new registries. There are two registry additions and both are
accurate with the rest of the document and seem fine to me.

>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

# 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?

It had broad, although at times shallow, consensus. Nobody was ever really opposed.
This is typical of the HTTPAPI WG, which has a mix of people who are interested
in different aspects of HTTP API's.

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

Earlier in the draft history, there was a suggestion that this concept is really
part of a larger lifecycle for APIs. After a couple of months nobody stepped
forward to work on such a document, and the Chairs decided (backed by no
opposition from the WG membership) to proceed with "just" deprecation.

There was also a (relatively) large amount of discussion around one
particular issue, https://github.com/ietf-wg-httpapi/deprecation-header/issues/11
The Chairs determined rough consensus for the authors's proposed resolution.

>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, neither.

>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)?

The draft lists several implementations in Appendix A, including other IETF work at
https://tools.ietf.org/html/draft-loffredo-regext-rdap-jcard-deprecation

Implementations and questions have been discussed on many websites, including StackOverflow,
the Python library GitHub, and a nice blog post (at https://imhoratiu.wordpress.com/2021/01/20/respectful-rest-apis-sunset-and-deprecation-http-headers/)
which compare header with Sunset (RFC 8594)

## 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.

There is membership overlap with HTTPBIS WG, which is the obvious place to
collaborate and it has been done informally.

>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.

None needed.

>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]?

n/a

>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.

n/a

## 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?

ART (now WIT).  No issues.

>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?

standards track and that makes sense since it defines a new HTTP header field.

>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.  No IPR claims.

>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, both of them want to be listed as authors.

>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.)

Nothing important. One missing reference to the RFC for URI.

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

There's a down ref question in the nits output which we would like guidance on.
Other then that, all seems fine.

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

None.

>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.

The doc references "SFBIS" draft, so this should probably be put in the same
cluster as that.  See https://datatracker.ietf.org/doc/draft-ietf-httpbis-sfbis/

>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?

Just the one; see prev question.

>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 changes.

>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]).

There are no new registries. There are two registry additions and both are
accurate with the rest of the document and seem fine to me.

>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

This document has been stable since December 2023, and the two remaining issues could be closed during WGLC.

Please review this and see if we should move it forward.  Post to the email list, httpapi@ietf.org

Thanks!