Internet-Draft api-catalog June 2023
Smith Expires 4 December 2023 [Page]
Workgroup:
Internet Engineering Task Force
Internet-Draft:
draft-smith-api-catalog-02
Published:
Intended Status:
Standards Track
Expires:
Author:
K. Smith, Ed.
Vodafone

api-catalog: A well-known URI to help discovery of APIs

Abstract

This document defines the "api-catalog" well-known URI. It is intended to facilitate discovery of the APIs published by a Web host.

Status of This Memo

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

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on 4 December 2023.

Table of Contents

1. Introduction

A Web host may publish Application Programming Interfaces (APIs) to encourage requests for interaction from external parties. Such APIs must be discovered before they may be used - i.e., the external party needs to know what APIs a given Web host exposes, including their purpose, any constraints to use, and the endpoints to interact with the APIs. To faciliate discovery of this information, this document proposes a well-known URI, 'api-catalog', as a location where a Web host's API endpoints are listed and described.

1.1. Goals and non-goals

The primary goal is to facilitate the discovery of both a Web Host's public API endpoints, and metadata that informs the potential API client of the purpose of each API and any constraints around usage.

Non-goals: this document does not mandate paths for API endpoints. i.e., it does not mandate that my_example_api should be available at example.com/.well-known/api-catalog/my_example_api (although it is not forbidden to do so).

1.2. Requirements Language

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] when, and only when, they appear in all capitals, as shown here.

2. Using the 'api-catalog' well-known URI

The api-catalog well-known URI is intended for HTTP(S) servers that publish APIs and wish to facilitate their discovery. Since the purpose of the api-catalog well-known URI is to facilitate API discovery with minimal prior knowledge, it is recommended that /.well-known/api-catalog be hosted at a predictable hostname, i.e. www.example.com . It may also be hosted at other hostnames, e.g. api.example.com, developer.example.com etc.

A Web host (example.com) supporting this URI:

3. Associated Media type: the api-catalog linkset

A request to the api-catalog well-known URI SHALL return a linkset [RFC9264] containing an array of links with the link relation "api-bookmarks" and an anchor representing the entity hosting the APIs. Following each link SHOULD return a machine-readable description of the API with sufficient information to decide if, and understand how, to use the API. (Editor's note: we can recommend the format for this machine-readble description, e.g. https://restdesc.org/)

Example request:


GET .well-know/api-catalog HTTP/1.1
Host: example.com
Accept: application/linkset+json

HTTP/1.1 200 OK
Date: Mon, 01 Jun 2023 00:00:01 GMT
Server: Apache-Coyote/1.1
Content-Type: application/linkset+json

{
"linkset": [{
        "anchor": https://example.com/,
        "api-bookmarks": [{
                "href": https://developer.example.com/apis/foo_api
        }, {
                "href": https://developer.example.com/apis/bar_api
        }, {
                "href": https://developer.example.com/apis/cantona_api
        }
        ]
}]
}

Figure 1: api-catalog linkset example

5. Conformance to RFC8615

The requirements in section 3 of [RFC8615] for defining Well-Known Uniform Resource Identifiers are met as follows:

5.1. Path prefix

The api-catalog URI SHALL be appended to the /.well-known/ path-prefix for "well-known locations".

5.2. Supported URI schemes

The api-catalog well-known URI may be used with the HTTP and HTTPS URI schemes.

5.3. Registration of the api-catalog well-known URI

See Section 6 considerations below.

6. IANA Considerations

6.1. The api-catalog well-known URI

This specification registers the "api-catalog" well-known URI in the Well-Known URI Registry as defined by [RFC6415] .

URI suffix: api-catalog

Specification document(s): draft-smith-api-catalog-02

Related information: The "api-catalog" documents obtained from the same host using the HTTP and HTTPS protocols (using default ports) MUST be identical.

This specification registers the "api-catalog" link relation by following the procedures per section 4.2.2 of [RFC8288] (Editor's note: this is TODO).

This specification registers the "api-bookmarks" link relation by following the procedures per section 4.2.2 of [RFC8288] (Editor's note: this is TODO).

7. Security Considerations

TBD

8. References

8.1. Normative References

[RFC6415]
Hammer-Lahav, E., Ed. and B. Cook, "Web Host Metadata", RFC 6415, DOI 10.17487/RFC6415, , <https://www.rfc-editor.org/info/rfc6415>.
[RFC8288]
Nottingham, M., "Web Linking", RFC 8288, DOI 10.17487/RFC8288, , <https://www.rfc-editor.org/info/rfc8288>.
[RFC8615]
Nottingham, M., "Well-Known Uniform Resource Identifiers (URIs)", RFC 8615, DOI 10.17487/RFC8615, , <https://www.rfc-editor.org/info/rfc8615>.
[RFC9264]
Wilde, E. and H. Van de Sompel, "Linkset: Media Types and a Link Relation Type for Link Sets", RFC 9264, DOI 10.17487/RFC9264, , <https://www.rfc-editor.org/info/rfc9264>.

8.2. Informative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.

Acknowledgements

TODO

Author's Address

Kevin Smith (editor)
Vodafone
One Kingdom Street
London
W2 6BY
United Kingdom