The Link-Template HTTP Header Field
draft-ietf-httpapi-link-template-04

[Ballot comment]
Feedback from incoming ART AD, Orie Steele:

I'd prefer to see specific security considerations associated with "Display Strings", based on this MUST:

"These Parameter values MUST be Strings, unless they contain non-ASCII characters, in which case they MUST be Display Strings. "

... and the following comment in the normative reference:

"It is NOT RECOMMENDED that they be used in situations where a String (Section 3.3.3) or Token (Section 3.3.4) would be adequate, because Unicode has processing considerations (e.g., normalization) and security considerations (e.g., homograph attacks) that make it more difficult to handle correctly."

[Ballot comment]
Hi Mark,

Thanks for this document.  I have one minor comment:

(1) p 1, sec 1.  Introduction

  This specification defines a HTTP header field [HTTP] for conveying
  templates for links in the headers of a HTTP message.  It is
  complimentary to the Link header field defined in Section 3 of
  [WEB-LINKING], which carries links directly.

As a minor comment, it wasn't entirely clear to me what these HTTP templates are used for and why it is helpful to carry them in the HTTP headers (as opposed to the body).  Hence please consider whether adding a paragraph to the intro, highlighting potential use cases, or perhaps giving an example of what is useful for may be helpful to readers.

Regards,
Rob

[Ballot comment]
Nice and clear shepherd write-up for a useful document (even to my non-expert eyes).

Minor regret: the companion documents in other WG are not on the same telechat date.

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

The IANA Functions Operator has completed its review of draft-ietf-httpapi-link-template-02. If any part of this review is inaccurate, please let us know.

The IANA Functions Operator understands that, upon approval of this document, there is a single action which we must complete.

In the Hypertext Transfer Protocol (HTTP) Field Name Registry located at:

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

a single new registration is to be made as follows:

Field Name: Link-Template
Template:
Status: permanent
Reference: [ RFC-to-be ]

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 this is 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.

For definitions of IANA review states, please see:

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

Thank you,

David Dong
IANA Services Specialist

The following Last Call announcement was sent out (ends 2023-05-29):

From: The IESG
To: IETF-Announce
CC: Zaheduzzaman.Sarker@ericsson.com, darrel@tavis.ca, draft-ietf-httpapi-link-template@ietf.org, httpapi-chairs@ietf.org, httpapi@ietf.org, rsalz@akamai.com
Reply-To: last-call@ietf.org
Sender:
Subject: Last Call:  (The Link-Template 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 Link-Template 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 2023-05-29. 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 the Link-Template HTTP header field,
  providing a means for describing the structure of a link between two
  resources, so that new links can be generated.




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



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?

A few "prominent in the field" people were those most active in the discussions.
Consensus to adopt was strong, WGLC received no comments.
There was little change over the course of the revisions; this is probably
because it was trying to solve a single problem, and the author is an expert.
There was interest in using this.

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

No. Some found the `var-base` concept confusing, but it does have an example and should
be familiar to those involved in URI's.

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)?

N/A.

## 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. Several people see the need to be able to "templatize" HTTP link relations.
The authors (and many of those who reviewed and comment) are active members of
both HTTPAPI and HTTP-BIS working groups.

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.

N/A

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?

In the view of the Chairs (one of whom is the Shepherd) this is complete,
understandable, and ready to submit for publication.

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?

It's all fine.

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. As this adds an HTTP header field, that is appropriate. Yes, the
desired state is properly reflected.

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.

The author says he is not aware of any IPR.

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.)

draft-ietf-httpbis-semantics is now RFC 9110; this can be corrected in AUTH48.

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

All good.

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

There are 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.

No.

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]).

This adds a new HTTP header field into the registry, with semantics described in the document.

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.

None.

[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://trac.ietf.org/trac/ops/wiki/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://trac.ietf.org/trac/iesg/wiki/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?

A few "prominent in the field" people were those most active in the discussions.
Consensus to adopt was strong, WGLC received no comments.
There was little change over the course of the revisions; this is probably
because it was trying to solve a single problem, and the author is an expert.
There was interest in using this.

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

No. Some found the `var-base` concept confusing, but it does have an example and should
be familiar to those involved in URI's.

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)?

N/A.

## 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. Several people see the need to be able to "templatize" HTTP link relations.
The authors (and many of those who reviewed and comment) are active members of
both HTTPAPI and HTTP-BIS working groups.

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.

N/A

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?

In the view of the Chairs (one of whom is the Shepherd) this is complete,
understandable, and ready to submit for publication.

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?

It's all fine.

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. As this adds an HTTP header field, that is appropriate. Yes, the
desired state is properly reflected.

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.

The author says he is not aware of any IPR.

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.)

draft-ietf-httpbis-semantics is now RFC 9110; this can be corrected in AUTH48.

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

All good.

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

There are 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.

No.

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]).

This adds a new HTTP header field into the registry, with semantics described in the document.

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.

None.

[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://trac.ietf.org/trac/ops/wiki/yang-review-tools
[5]: https://www.rfc-editor.org/rfc/rfc8342.html
[6]: https://trac.ietf.org/trac/iesg/wiki/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/

The Author believes this document is ready for working group last call. Having re-read it, at least one of the WG chairs agrees :)

Please reaad the document -- it's really short! -- and post any comments to the mailing list.  Indications of support for advancing this to the IESG would be helpful.

Thanks.