Building Blocks for HTTP APIsM. Nottingham
Internet-DraftJuly 1, 2024
Intended status: Standards Track
Expires: January 2, 2025

The Link-Template HTTP Header Field


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

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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

Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., “HTTP Semantics”, STD 97, RFC 9110, DOI 10.17487/RFC9110, June 2022, <>.
Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels”, BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <>.
Leiba, B., “Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words”, BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <>.
Nottingham, M. and P. Kamp, “Structured Field Values for HTTP”, Internet-Draft draft-ietf-httpbis-sfbis-06 (work in progress), April 2024.
Davis, M. and M. Suignard, “Unicode Security Considerations”, Unicode Technical Report #16, September 2014, <>.
Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax”, STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005, <>.
Gregorio, J., Fielding, R., Hadley, M., Nottingham, M., and D. Orchard, “URI Template”, RFC 6570, DOI 10.17487/RFC6570, March 2012, <>.
Nottingham, M., “Web Linking”, RFC 8288, DOI 10.17487/RFC8288, October 2017, <>.

Author's Address

Mark Nottingham