Network Working Group E. Pot
Internet-Draft
Intended status: Standards Track G. Sullice
Expires: May 5, 2021 Acquia, Inc.
November 01, 2020
JSON serialization for Web Linking
draft-pot-json-link-02
Abstract
This specification defines a serialization of Web Linking [RFC8288]
in the JSON [RFC8259] format.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Format . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. The link object. . . . . . . . . . . . . . . . . . . . . 3
2.1.1. rel . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.2. href . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.3. anchor . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.4. Other attributes . . . . . . . . . . . . . . . . . . 4
2.1.5. Extension Attributes . . . . . . . . . . . . . . . . 4
2.1.6. Example . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Lists of links . . . . . . . . . . . . . . . . . . . . . 4
2.2.1. Example . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Document-level links . . . . . . . . . . . . . . . . . . 5
2.3.1. Example . . . . . . . . . . . . . . . . . . . . . . . 5
3. IANA considerations . . . . . . . . . . . . . . . . . . . . . 6
4. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Normative References . . . . . . . . . . . . . . . . . . 6
4.2. Informative References . . . . . . . . . . . . . . . . . 6
Appendix A. Typescript definitions . . . . . . . . . . . . . . . 7
Appendix B. JSON-SCHEMA definitions . . . . . . . . . . . . . . 7
B.1. Link . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Appendix C. Changelog . . . . . . . . . . . . . . . . . . . . . 8
C.1. Changes since -?? . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
There are many JSON-based standards and formats that require the need
to express a link. Examples can be found in [draft-kelly-json-hal],
[JSON-API], [WEBTHING], [draft-nottingham-json-home],
[COLLECTIONJSON], [SIREN] and many others.
Because there hasn't been an accepted reference for serializing Web
Links in JSON, it's typical for authors of new formats to invent
their own. This has resulted in many minor differences between
serializations, making it difficult to write generic parsers.
This document is an attempt to define a standard JSON serialization
for Web linking. A primary goal is to define a format that's
relatively uncontroversial and similar to existing serializations.
Furthermore, this specification defines an optional format for groups
of links and a recommendation for defining document-wide links.
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2. Format
2.1. The link object.
A link will be encoded as a JSON [RFC8259] object. The object might
support the properties from the following chapters, but only "rel"
and "href" are required.
2.1.1. rel
The "rel" property refers to Section 3.3 of [RFC8288]. The "rel"
property must be a string.
There is no support to encode multiple relation types for a single
link. To encode multiple relation types, the link must appear
multiple times in the document.
2.1.2. href
The "href" property refers to the Link Target, defined in Section 3.1
of [RFC8288].
The property is required and must be specified as a string.
2.1.3. anchor
The "anchor" attribute is defined in Section 3.2 of [RFC8288]. This
specification alters the behavior of anchor. By default, if anchor
is not specified the link context is considered to be the URL of the
representation it is associated with.
If the link appears alongside a link with the 'self' relation type
(for example in Section 2.2 of links, the target of the self link
MUST be used as the default link context, unless the anchor attribute
is defined.
If the link is not part of a list of links that has a link relation
of type 'self', the default behavior is to use the URL of the
representation it's associated with.
However, implementors of this specification MAY override this.
Because JSON links may have deeper contextual meaning depending on
where it appears in the document.
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2.1.4. Other attributes
The link object may also encode the "hreflang", "media", "type"
attributes. These properties are all defined in Section 3.4.1 of
[RFC8288]. In their JSON serialization they are all optional, and
must be encoded as a string.
Section 3.4.1 also defines a "title*" attribute, which may contain an
alternative encoding for the "title" attribute.
JSON only supports UTF-8 encoding. As such, it is not needed to make
this distinction. The link title is always encoded using the "title"
property.
2.1.5. Extension Attributes
Similar to [RFC8288], other documents may define new target
attributes for links. Parsers that don't understand any attributes
appearing on a link MUST ignore them.
2.1.6. Example
This section is non-normative.
{
"href": "https://evertpot.com/",
"rel": "author",
"title": "Evert Pot"
}
2.2. Lists of links
Authors that wish to encode a set of links in a document, SHOULD use
an array of links.
2.2.1. Example
This section is non-normative.
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[
{
"href": "https://evertpot.com/",
"rel": "author",
"title": "Evert Pot"
},
{
"href": "https://test.example/",
"rel": "self"
}
}
2.3. Document-level links
If a JSON representation wants to define document-level links,
implementors of this specification SHOULD use a top-level "links"
property to define these.
The "links" property contains a list of links.
The links appearing in this list are considered semantically
equivalent to the links appear in the "Link" header, as defined in
Section 3.5 of [RFC8288].
Implementors of this specification MAY make an effort to expose links
from the HTTP Link header and the document-level links via a unified
interface.
2.3.1. Example
This section is non-normative.
{
"links": [
{
"href": "https://evertpot.com/",
"rel": "author",
"title": "Evert Pot"
},
{
"href": "https://test.example/",
"rel": "self"
}
]
}
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3. IANA considerations
We would like to register the 'application/links+json' media-type for
documents wishing to implement this spec.
TBD?
4. References
4.1. Normative References
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
[RFC8288] Nottingham, M., "Web Linking", RFC 8288,
DOI 10.17487/RFC8288, October 2017,
<https://www.rfc-editor.org/info/rfc8288>.
4.2. Informative References
[COLLECTIONJSON]
Mike Amundsen, ., "Collection+JSON", n.d.,
<http://amundsen.com/media-types/collection/format/>.
[draft-kelly-json-hal]
Kelly, M., "JSON Hypertext A:wpplication Language", n.d.,
<https://tools.ietf.org/html/draft-kelly-json-hal>.
[draft-nottingham-json-home]
Nottingham, M., "Home Documents for HTTP APIs", n.d.,
<https://tools.ietf.org/html/draft-nottingham-json-home>.
[JSON-API]
"JSON:API", n.d., <https://jsonapi.org/format/>.
[SIREN] Kevin Swiber, ., "Siren: a hypermedia specification for
representing entities", n.d.,
<https://github.com/kevinswiber/siren>.
[WEBTHING]
Ben Francis, ., "Web Thing API", n.d.,
<https://iot.mozilla.org/wot/>.
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Appendix A. Typescript definitions
type Link = {
href: string,
rel: string,
anchor?: string,
hreflang?: string,
media?: string,
type?: string,
}
type LinkSet = Link[];
type DocumentLinks = {
links: LinkSet
}
Appendix B. JSON-SCHEMA definitions
B.1. Link
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{
"$schema": "http://json-schema.org/draft-07/schema#",
"$id": "...",
"type": "object",
"additionalProperties": true,
"required": [
"href",
"rel"
],
"properties": {
"href": {
"type": "string",
"format":"uri-reference"
},
"rel": {
"type": "string",
},
"title": {
"type": "string"
},
"type": {
"type": "string"
},
"hreflang": {
"type": "string",
},
"media": {
"type": "string"
}
}
}
Appendix C. Changelog
C.1. Changes since -??
Authors' Addresses
Evert Pot
Email: me@evertpot.com
URI: https://evertpot.com/
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Gabriel Sullice
Acquia, Inc.
Email: gabriel@sullice.com
URI: https://sullice.com
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