Building Blocks for HTTP APIsM. Nottingham
Internet-DraftFebruary 19, 2024
Intended status: Standards Track
Expires: August 22, 2024

The Link-Template HTTP Header Field

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.

About This Document

This note is to be removed before publishing as an RFC.

The latest revision of this draft can be found at <https://ietf-wg-httpapi.github.io/link-template/draft-ietf-httpapi-link-template.html>. Status information for this document may be found at <https://datatracker.ietf.org/doc/draft-ietf-httpapi-link-template/>.

Discussion of this document takes place on the Building Blocks for HTTP APIs Working Group mailing list (<mailto:httpapi@ietf.org>), which is archived at <https://mailarchive.ietf.org/arch/browse/httpapi/>. Subscribe at <https://www.ietf.org/mailman/listinfo/httpapi/>.

Source for this draft and an issue tracker can be found at <https://github.com/ietf-wg-httpapi/link-template>.

Status of this Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on August 22, 2024.

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1. Introduction

[URI-TEMPLATE] defines a syntax for templates that, when expanded using a set of variables, results in a URI [URI].

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.

1.1. Notational Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

This specification uses the following terms from [STRUCTURED-FIELDS]: List, String, Display String, Parameter.



3. Security Considerations

The security consideration for the Link header field in [WEB-LINKING] and those for URI Templates [URI-TEMPLATE] both apply.

Target attributes that are conveyed via Display Strings can be vulnerable to a wide variety of attacks. See [UNICODE-SECURITY] for advice regarding their handling. Specific advice is not given by this specification, since there are a variety of potential use cases for such attributes.


4. IANA Considerations

This specification enters the "Link-Template" into the Hypertext Transfer Protocol (HTTP) Field Name Registry.

5. Normative References

[HTTP]
Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., “HTTP Semantics”, STD 97, RFC 9110, DOI 10.17487/RFC9110, June 2022, <https://www.rfc-editor.org/info/rfc9110>.
[RFC2119]
Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels”, BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174]
Leiba, B., “Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words”, BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[STRUCTURED-FIELDS]
Nottingham, M. and P. Kamp, “Structured Field Values for HTTP”, Internet-Draft draft-ietf-httpbis-sfbis-05 (work in progress), January 2024.
[UNICODE-SECURITY]
Davis, M. and M. Suignard, “Unicode Security Considerations”, Unicode Technical Report #16, September 2014, <http://www.unicode.org/reports/tr36/>.
[URI]
Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax”, STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005, <https://www.rfc-editor.org/info/rfc3986>.
[URI-TEMPLATE]
Gregorio, J., Fielding, R., Hadley, M., Nottingham, M., and D. Orchard, “URI Template”, RFC 6570, DOI 10.17487/RFC6570, March 2012, <https://www.rfc-editor.org/info/rfc6570>.
[WEB-LINKING]
Nottingham, M., “Web Linking”, RFC 8288, DOI 10.17487/RFC8288, October 2017, <https://www.rfc-editor.org/info/rfc8288>.

Author's Address

Mark Nottingham
Prahran
Australia
EMail: mnot@mnot.net
URI: https://www.mnot.net/