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Applications and Real-Time HTTPAPI Internet-Draft This document registers the following media types used in APIs on the IANA Media Types registry: application/openapi+json, and application/openapi+yaml. About This Document Status information for this document may be found at . Discussion of this document takes place on the HTTPAPI Working Group mailing list (), which is archived at . Subscribe at . Working Group information can be found at . Source for this draft and an issue tracker can be found at .

Introduction OpenAPI Specification version 3 and above is a consolidated standard for describing HTTP APIs using the JSON and YAML data format. To increase interoperability when processing API description and leverage content negotiation mechanisms when exchanging OpenAPI description resources this specification register the following media types: application/openapi+json and application/openapi+yaml.

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 when, and only when, they appear in all capitals, as shown here. These words may also appear in this document in lower case as plain English words, absent their normative meanings. This document uses the Augmented BNF defined in and updated by . The terms "content", "content negotiation", "resource", and "user agent" in this document are to be interpreted as in .

Media Type registrations This section describes the information required to register the above media types according to .

The OpenAPI Media Types The OpenAPI Specification Media Types convey OpenAPI document (OAS) files as defined in for version 3.0 and above. Those files can be serialized in or . Since there are multiple OpenAPI Specification versions, those media types support the version parameter. The following example conveys the desire of a client to receive an OpenAPI Specification resource preferably in the following order:

1. openapi 3.1 in YAML
2. openapi 3.0 in YAML
3. any openapi version in JSON

Media Type application/openapi+json The following information serves as the registration form for the application/openapi+json media type.

Type name:

application

Subtype name:

openapi+json

Required parameters:

None

Optional parameters:

version; unrecognized parameters should be ignored

Encoding considerations:

Same as "application/json"

Security considerations:

See of this document, "application/json" and

Interoperability considerations:

See "application/json" and

Published specification:

this document,

Applications that use this media type:

HTTP

Fragment identifier considerations:

or the specific version of the OpenAPI document.

Additional information:

• Deprecated alias names for this type: N/A
• Magic number(s): N/A
• File extension(s): json
• Macintosh file type code(s): N/A

Person and email address to contact for further information:

See Authors' Addresses section.

Intended usage:

COMMON

Restrictions on usage:

None.

Author:

See Authors' Addresses section.

Change controller:

IETF

Media Type application/openapi+yaml The following information serves as the registration form for the application/openapi+yaml media type.

Type name:

application

Subtype name:

openapi+yaml

Required parameters:

N/A

Optional parameters:

version; unrecognized parameters should be ignored

Encoding considerations:

Same as "+yaml" Structured Syntax Suffix

Security considerations:

See of this document, "+yaml" Structured Syntax Suffix and

Interoperability considerations:

See "+yaml" Structured Syntax Suffix and

Published specification:

Applications that use this media type:

HTTP

Fragment identifier considerations:

or the specific version of the OpenAPI document.

Additional information:

• Deprecated alias names for this type: N/A
• Magic number(s): N/A
• File extension(s): Same as "application/yaml"
• Macintosh file type code(s): N/A

Person and email address to contact for further information:

See Authors' Addresses section

Intended usage:

COMMON

Restrictions on usage:

None.

Author:

See Authors' Addresses section

Change controller:

IETF

Interoperability Considerations Interoperability requirements for media type registrations are discussed in Section 4.6 of . and in the Interoperability Considerations of the "+yaml" Structured Syntax Suffix.

Security Considerations Security requirements for media type registrations are discussed in Section 4.6 of . and in the Security Considerations of the "+yaml" Structured Syntax Suffix.

General Considerations All REST API Media Types might reference nested or external resources, as well as processable information like HTML. Implementations that try to dereference or process those resource automatically might be subject to various security risks, from resource exhaustion (e.g., caused by cyclic references) to retrieval and processing of malicious code (e.g., embedded as markup language).

IANA Considerations This specification defines the following new Internet media types . IANA is asked to update the "Media Types" registry at https://www.iana.org/assignments/media-types with the registration information provided in the sections below.

Media Type	Registration information section
application/openapi+yaml	of this document
application/openapi+json	of this document

Normative References JavaScript Object Notation (JSON) is a lightweight, text-based, language-independent data interchange format. It was derived from the ECMAScript Programming Language Standard. JSON defines a small set of formatting rules for the portable representation of structured data. This document removes inconsistencies with other specifications of JSON, repairs specification errors, and offers experience-based interoperability guidance. In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. Internet technical specifications often need to define a formal syntax. Over the years, a modified version of Backus-Naur Form (BNF), called Augmented BNF (ABNF), has been popular among many Internet specifications. The current specification documents ABNF. It balances compactness and simplicity with reasonable representational power. The differences between standard BNF and ABNF involve naming rules, repetition, alternatives, order-independence, and value ranges. This specification also supplies additional rule definitions and encoding for a core lexical analyzer of the type common to several Internet specifications. [STANDARDS-TRACK] This document extends the base definition of ABNF (Augmented Backus-Naur Form) to include a way to specify US-ASCII string literals that are matched in a case-sensitive manner. The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypertext information systems. This document describes the overall architecture of HTTP, establishes common terminology, and defines aspects of the protocol that are shared by all versions. In this definition are core protocol elements, extensibility mechanisms, and the "http" and "https" Uniform Resource Identifier (URI) schemes. This document updates RFC 3864 and obsoletes RFCs 2818, 7231, 7232, 7233, 7235, 7538, 7615, 7694, and portions of 7230. This document defines procedures for the specification and registration of media types for use in HTTP, MIME, and other Internet protocols. This memo documents an Internet Best Current Practice.

Acknowledgements Thanks to Erik Wilde and David Biesack for being the initial contributors of this specification, and to Darrel Miller and Rich Salz for their support during the adoption phase. In addition to the people above, this document owes a lot to the extensive discussion inside and outside the HTTPAPI workgroup. The following contributors have helped improve this specification by opening pull requests, reporting bugs, asking smart questions, drafting or reviewing text, and evaluating open issues: Austin Wright, Ben Hutton and Jason Desrosiers.

FAQ

Q: Why this document?

After all these years, we still lack a proper media type for REST related document types. This has some security implications too (eg. wrt on identifying parsers or treat downloads)

Change Log RFC EDITOR PLEASE DELETE THIS SECTION.

Since -00

• Split YAML registrations in a separate I-D.

Since -04

• Split JSONSCHEMA registrations in a separate I-D.