Linkset: Media Types and a Link Relation Type for Link SetsAxwayerik.wilde@dret.nethttp://dret.net/netdret/Data Archiving and Networked Servicesherbert.van.de.sompel@dans.knaw.nlhttps://orcid.org/0000-0002-0715-6126This specification defines two formats and respective media types for representing sets of links as stand-alone documents. One format is JSON-based, the other aligned with the format for representing links in the HTTP "Link" header field. This specification also introduces a link relation type to support discovery of sets of links.Please discuss this draft on the "Building Blocks for HTTP APIs" mailing list ().Online access to all versions and files is available on GitHub ().Resources on the Web often use typed Web Links , either embedded in resource representations, for example using the <link> element for HTML documents, or conveyed in the HTTP "Link" header field for documents of any media type. In some cases, however, providing links in this manner is impractical or impossible and delivering a set of links as a stand-alone document is preferable.Therefore, this specification defines two formats for representing sets of Web Links and their attributes as stand-alone documents. One serializes links in the same format as used in HTTP the Link header field, and the other serializes links in JSON. It also defines associated media types to represent sets of links and the "linkset" relation type that supports discovery of any resource that conveys a set of links as a stand-alone document.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.This specification uses the terms "link context" and "link target" as defined in .In the examples provided in this document, links in the HTTP "Link" header field are shown on separate lines in order to improve readability.
Note, however, that as per , line breaks are deprecated in values for HTTP fields; only whitespaces and
tabs are supported as separators.The following sections describe use cases in which providing links by means of a standalone document instead of in an HTTP "Link" header field or as links embedded in the resource representation is advantageous or necessary.For all scenarios, links could be provided by means of a stand-alone document that is formatted according to the JSON-based serialization, the serialization aligned with the HTTP "Link" field format, or both. The former serialization is motivated by the widespread use of JSON and related tools, which suggests that handling sets of links expressed as JSON documents should be attractive to developers. The latter serialization is provided for compatibility with the existing serialization used in the HTTP "Link" field and to allow reuse of tools created to handle it.It is important to keep in mind that when providing links by means of a standalone representation, other links can still be provided using other approaches, i.e. it is possible to combine various mechanisms to convey links.In some cases it is useful that links pertaining to a resource are provided
by a server other than the one that hosts the resource. For example, this allows:
Providing links in which the resource is involved not just as link context but
also as link target.
Providing links pertaining to the resource that the server hosting that
resource is not aware of.
External management of links pertaining to the resource in a special-purpose link
management service.
In such cases, links pertaining to a resource can be provided by another, specific resource.
That specific resource may be managed by the same or by another custodian as the resource to which the links pertain.
For clients intent on consuming links provided in that manner, it would be beneficial if the following conditions were met:
Links are provided in a document that uses a well-defined media type.
The resource to which the provided links pertain is able to link to the resource that provides these links using a well-known
link relation type.
These requirements are addressed in this specification through the definition of two media types and a link relation type, respectively.In some cases, it is not straightforward to write links to the HTTP "Link" header field
from an application. This can, for example, be the case because not all
required link information is available to the application or because the
application does not have the capability to directly write HTTP fields.
In such cases, providing links by means of a standalone document can be a solution.
Making the resource that provides these links discoverable can be achieved by means of a
typed link.When conveying links in an HTTP "Link" header field, it is possible for the size of the HTTP
response fields to become unpredictable. This can be the case when links are determined
dynamically dependent on a range of contextual factors. It is possible to statically configure
a web server to correctly handle large HTTP response fields by specifying an upper bound
for their size. But when the number of links is
unpredictable, estimating a reliable upper bound is challenging.HTTP defines error codes related to excess communication
by the user agent ("413 Request Entity Too Large" and "414 Request-URI Too Long"), but no specific
error codes are defined to indicate that response field content exceeds the upper bound that can
be handled by the server, and thus it has been truncated.
As a result, applications take counter measures aimed at controlling
the size of the HTTP "Link" header field, for example by limiting the links they provide to those
with select relation types, thereby limiting the value of the HTTP "Link" header field to clients.
Providing links by means of a standalone document overcomes challenges related to the unpredictable
nature of the size of HTTP "Link" header fields.This section specifies two document formats to convey a set of links. Both are based on the abstract model
specified in Web Linking
that defines a link as consisting of a "link context", a "link relation type", a "link target",
and optional "target attributes":
The format defined in is near identical to the field value
of the HTTP "Link" header field as specified in Web Linking .
The format defined in is based on JSON.
Note that deprecates the "rev" construct that was provided by as a means to express links with a directionality that is the inverse of direct links that use the "rel" construct. In both serializations for link sets defined here, inverse links may be represented as direct links using the "rel" construct and by switching the position of the resources involved in the link.This document format is near identical to the field value of the
HTTP "Link" header field as defined in
, more specifically by
its ABNF production rule for "Link" and subsequent ones. It differs only from the format for field values of the
HTTP "Link" header in that not only spaces and horizontal tabs are allowed as separators but also newline
characters as a means to improve readability for humans.
The use of non-ASCII characters in the field value of the HTTP "Link" Header field is not allowed.The assigned media type for this format is "application/linkset".When converting an "application/linkset" document to a field value for the
HTTP "Link" header, newline characters SHOULD be removed in order to comply with
.In order to support use cases where "application/linkset" documents are re-used
outside the context of an HTTP interaction,
it is RECOMMENDED to make them self-contained by adhering to the following guidelines:
For every link provided in the set of links, explicitly provide the link context
using the "anchor" attribute.
For link context ("anchor" attribute) and link target
("href" attribute), use URI references that are not relative references (as defined in ).
If these recommendations are not followed, interpretation of links in "application/linkset" documents will depend on
which URI is used as context.It should be noted that the "application/linkset" format specified here is different than the "application/link-format"
format specified in in that the former fully matches the
field value of the HTTP "Link" header field as defined in , whereas
the latter introduces constraints on that definition to meet requirements for Constrained RESTful Environments.This document format uses JSON as the syntax to represent
a set of links. The set of links follows the abstract model defined by Web Linking .The assigned media type for this format is "application/linkset+json".In order to support use cases where "application/linkset+json" documents are re-used
outside the context of an HTTP interaction,
it is RECOMMENDED to make them self-contained by adhering to the following guidelines:
For every link provided in the set of links, explicitly provide the link context
using the "anchor" member.
For link context ("anchor" member) and link target
("href" member), use URI references that are not relative references (as defined in ).
If these recommendations are not followed, interpretation of "application/linkset+json" will depend on which URI is used as context URI.The "application/linkset+json" serialization allows for OPTIONAL support of a JSON-LD serialization.
This can be achieved by adding an appropriate context to the "application/linkset+json" serialization using the approach described in
. Communities of practice can decide which context best meets their application needs.
shows an example of a possible context that, when added to a JSON serialization,
allows it to be interpreted as Resource Description Framework (RDF) data.In the JSON representation of a set of links:
A set of links is represented in JSON as an object which MUST contain "linkset" as its sole member.
The "linkset" member is an array in which a distinct JSON object -
the "link context object" (see ) -
is used to represent links that have the same link context.
Even if there is only one link context object, it MUST be wrapped in an array.
In the JSON representation one or more links that have the same link context
are represented by a JSON object, the link context object. A link context object
adheres to the following rules:
Each link context object MAY contain an "anchor" member with a value that represents
the link context. If present, this value MUST be a URI reference
and SHOULD NOT be a relative reference as per .
For each distinct relation type that the link context has with link targets,
a link context object MUST contain an additional member.
This member is an array in which a distinct JSON object
- the "link target object" (see ) -
MUST be used for each link target for which the relationship with
the link context (value of the encompassing anchor member) applies. The name
of this member expresses the relation type of the link as follows:
For registered relation types (),
the name of this member is the registered name of the relation type.
For extension relation types (),
the name of this member is the URI that uniquely represents the relation type.
Even if there is only one link target object it MUST be wrapped in an array.
In the JSON representation a link target is represented by a JSON object, the link target object.
A link target object adheres to the following rules:
Each link target object MUST contain an "href" member with a value that represents
the link target. This value MUST be a URI reference and SHOULD NOT be a relative reference
as per . Cases where the href member is present, but no value is provided
for it (i.e. the resource providing the set of links is the target of the link
in the link target object) MUST be handled by providing an "href" member with an empty string ("href": "").
In many cases, a link target is further qualified by target attributes.
Various types of attributes exist and they are conveyed as additional members of the link target object
as detailed in .
The following example of a JSON-serialized set of links represents one
link with its core components: link context, link relation
type, and link target.The following example of a JSON-serialized set of links represents two links
that share link context and relation type but have different link targets.The following example shows a set of links that represents two links, each with
a different link context, link target, and relation type.
One relation type is registered, the other is an extension relation type.A link may be further qualified by target attributes as defined by Web Linking.
Three types of attributes exist:
Serialisation-defined attributes described in Web Linking.
Extension attributes defined and used by communities as allowed by
.
Internationalized versions of the "title" attribute defined by and of extension attributes
allowed by .
The handling of these different types of attributes is described in the sections below. defines the following target attributes that may be used to annotate links:
"hreflang", "media", "title", "title*", and "type";
these target attributes follow different occurrence and value patterns.
In the JSON representation, these attributes MUST be conveyed as additional
members of the link target object as follows:
"hreflang": The optional and repeatable "hreflang" target attribute
MUST be represented by an array (even if there only is one value to be represented),
and each value in that array MUST be a string - representing one value
of the "hreflang" target attribute for a link - which follows the same
model as in the syntax.
"media": The optional and not repeatable "media" target attribute MUST be
represented by a "media" member
in the link target object, and its value MUST be a string that follows the
same model as in the syntax.
"type": The optional and not repeatable "type" target attribute MUST be represented by a "type" member
in the link target object, and its value MUST be a string that follows the
same model as in the syntax.
"title": The optional and not repeatable "title" target attribute MUST be represented by a "title"
member in the link target object, and its value MUST be a string that follows
the same model as in the syntax.
"title*": The optional and not repeatable "title*" target attribute
is motivated by character encoding
and language issues and follows the model defined in .
The details of the JSON
representation that applies to title* are described in
.
The following example illustrates how the repeatable "hreflang" and the
not repeatable "type" target attributes are represented in a link target object.In addition to the target attributes described in ,
also supports
attributes that follow the content model of .
In , these target
attributes are recognizable by the use of a trailing asterisk in the attribute name,
such as "title*".
The content model of uses a string-based microsyntax
that represents the character encoding, an optional language tag,
and the escaped attribute value encoded according to the specified character encoding.The JSON serialization for these target attributes MUST be
as follows:
An internationalized target attribute is represented as a member of the link context object with
the same name (including the *) of the attribute.
The character encoding information
as prescribed by is not preserved; instead, the
content of the internationalized attribute is represented in the character encoding used for the JSON set of links.
The value of the internationalized target attribute is an
array that contains one or more JSON objects. The name of one member
of such JSON object is "value"
and its value is the actual content (in its unescaped version) of the internationalized target attribute, i.e. the
value of the attribute from which
the encoding and language information are removed.
The name of another, optional, member of such JSON object is "language" and
its value is the language tag
for the language in which the attribute content is conveyed.
The following example illustrates how the "title*" target attribute
defined by is represented in a link target object.The above example assumes that the German title contains an umlaut character (in the native syntax it would be encoded as title*=UTF-8'de'n%c3%a4chstes%20Kapitel),
which gets encoded in its unescaped form in the JSON representation.
Implementations MUST properly decode/encode internationalized target attributes that follow the model of when transcoding between the "application/linkset" and the "application/linkset+json" formats.Extension target attributes are attributes that are not defined by
(as listed in ), but are nevertheless
used to qualify links.
They can be defined by communities in any way deemed necessary, and it is up to them
to make sure their usage is understood by target applications.
However, lacking standardization, there is no interoperable
understanding of these extension attributes. One important consequence is that
their cardinality is unknown to generic applications. Therefore, in the JSON serialization,
all extension target attributes are treated as repeatable.The JSON serialization for these target attributes MUST be
as follows:
An extension target attribute is represented as a member of the link target object with the same name of the attribute, including the * if applicable.
The value of an extension attribute MUST be represented by an array, even if there only is one value to be represented.
If the extension target attribute does not have a name with a trailing asterisk,
then each value in that array MUST be a string that represents one value
of the attribute.
If the extension attribute has a name with a trailing asterisk
(it follows the content model of ),
then each value in that array MUST be a JSON object. The value of each such JSON object
MUST be structured as described in .
The example shows a link target object with three extension target attributes. The value for each extension target attribute is an array. The two first are regular extension target attributes, with the first one ("foo") having only one value and the second one ("bar") having two.
The last extension target attribute ("baz*") follows the naming rule of and therefore is encoded according to the serialization described in .The Web linking model () provides for the use of extension target attributes as discussed in
.
No other form of extensions SHOULD be used.
This limitation of the JSON format allows to unambiguously round trip between links provided in the HTTP "Link" header field,
sets of links serialized according to the "application/linkset" format, and sets of links serialized
according to the "application/linkset+json" format.
Cases may exist in which the use of extensions other than those of may be useful.
For example, when a link set publishers needs to include descriptive or technical metadata for internal consumption.
In case such extensions are used they MUST NOT change the semantics of the JSON members defined in this specification.
Agents that consume JSON linkset documents can safely ignore such extensions.As a means to convey specific constraints or conventions (as per ) that apply to a link set document,
the "profile" parameter MAY be used in conjunction with the media types "application/linkset" and
"application/linkset+json" detailed in
and , respectively.
For example, the parameter could be used to indicate that a link set uses a specific, limited set of link relation
types.The value of the "profile" parameter MUST be a non-empty list of space-separated URIs,
each of which identifies specific constraints or conventions that apply to the link set document.
Profile URIs MAY be registered in the IANA Profile URI Registry in the manner specified by .The presence of a "profile" parameter in conjunction with the "application/linkset" and
"application/linkset+json" media types does not change the semantics of
a link set. As such, clients with and without knowledge of profile URIs can use the same representation. shows an example of using the "profile" parameter in conjunction with the
"application/linkset+json" media type.The target of a link with the "linkset" relation type provides a set of links,
including links in which the resource that is the link context participates.A link with the "linkset" relation type MAY be provided in the header field and/or
the body of a resource's representation. It may also be discovered by other means, such as through
client-side information.A resource MAY provide more than one link with a "linkset" relation type.
Multiple such links can refer to the same set of links expressed using different
media types, or to different sets of links, potentially provided by different third-party services.A user agent that follows a "linkset" link MUST be aware that the set of links provided by the resource that is the target of the link
can contain links in which the resource that is the context of the link does not participate; it MAY decide to ignore those links.A user agent that follows a "linkset" link and obtains links for which anchors and targets are expressed as
relative references (as per ) MUST determine what the context is for these links; it SHOULD ignore links for which it is unable to
unambiguously make that determination.As a means to convey specific constraints or conventions (as per ) that apply to a link set document,
the "profile" attribute MAY be used in conjunction with the "linkset" link relation type.
For example, the attribute could be used to indicate that a link set uses a specific, limited set of link relation
types. The value of the "profile" attribute MUST be a non-empty
list of space-separated URIs, each of which identifies specific constraints or conventions that apply
to the link set document. Profile URIs MAY be registered in the IANA Profile URI Registry in the manner specified by .
shows an example of using the "profile" attribute on a link
with the "linkset" relation type, making both the link set and the profile(s) to which it complies discoverable. and
show examples whereby a set of links is provided as "application/linkset" and "application/linkset+json" documents, respectively.
illustrates the use of the "linkset" link relation type to support discovery of sets of links and
shows how to convey profile information pertaining to a links set. shows a client issuing an
HTTP GET request against resource <https://example.org/links/resource1>. shows the response to the GET request of
. The response contains a Content-Type header field
specifying that the media type of the response is "application/linkset". A set of links, revealing authorship and versioning related
to resource <https://example.org/resource1>, is provided in the response body. The HTTP "Link" header field indicates the availability
of an alternate representation of the set of links using media type "application/linkset+json".
; rel="alternate"
; type="application/linkset+json"
; rel="author"
; type="application/rdf+xml"
; anchor="https://example.org/resource1",
; rel="latest-version"
; type="text/html"
; anchor="https://example.org/resource1",
; rel="predecessor-version"
; type="text/html"
; anchor="https://example.org/resource1?version=3",
; rel="predecessor-version"
; type="text/html"
; anchor="https://example.org/resource1?version=2",
; rel="memento"
; type="text/html"
; datetime="Thu, 13 Jun 2019 09:34:33 GMT"
; anchor="https://example.org/resource1",
; rel="memento"
; type="text/html"
; datetime="Sun, 21 Jul 2019 12:22:04 GMT"
; anchor="https://example.org/resource1",
; rel="author"
; anchor="https://example.org/resource1#comment=1"
]]>
shows the client issuing an HTTP GET
request against <https://example.org/links/resource1>.
In the request, the client uses an "Accept" header field to indicate it prefers a response in the
"application/linkset+json" format. shows the response to the HTTP GET request of .
The set of links is serialized according to the media type "application/linkset+json".
; rel="alternate"
; type="application/linkset"
Content-Length: 1349
{ "linkset":
[
{ "anchor": "https://example.org/resource1",
"author": [
{ "href": "https://authors.example.net/johndoe",
"type": "application/rdf+xml"
}
],
"memento": [
{ "href": "https://example.org/resource1?version=1",
"type": "text/html",
"datetime": "Thu, 13 Jun 2019 09:34:33 GMT"
},
{ "href": "https://example.org/resource1?version=2",
"type": "text/html",
"datetime": "Sun, 21 Jul 2019 12:22:04 GMT"
}
],
"latest-version": [
{ "href": "https://example.org/resource1?version=3",
"type": "text/html"
}
]
},
{ "anchor": "https://example.org/resource1?version=3",
"predecessor-version": [
{ "href": "https://example.org/resource1?version=2",
"type": "text/html"
}
]
},
{ "anchor": "https://example.org/resource1?version=2",
"predecessor-version": [
{ "href": "https://example.org/resource1?version=1",
"type": "text/html"
}
]
},
{ "anchor": "https://example.org/resource1#comment=1",
"author": [
{ "href": "https://authors.example.net/alice"}
]
}
]
}]]>
shows a client issuing an
HTTP HEAD request against resource
<https://example.org/resource1>. shows the response to the HEAD request of
. The response contains an HTTP "Link" header field with
a link that has the "linkset" relation type. It indicates that a set of links is provided
by resource <https://example.org/links/resource1>, which
provides a representation with media type "application/linkset+json".
; rel="linkset"
; type="application/linkset+json"
Content-Length: 236
Content-Type: text/html;charset=utf-8
]]>
The examples in this section illustrate the use of the "profile" attribute for a link with the "linkset" link relation type and the "profile" attribute for a link set media type. The examples are inspired by the implementation of link sets by GS1 (the standards body behind many of the world's barcodes). shows a client issuing an
HTTP HEAD request against trade item 09506000134352 at <https://id.gs1.org/01/9506000134352>. shows the server's response to the request of
, including a "linkset" link with a "profile" attribute
that has the Profile URI <https://www.gs1.org/voc/?show=linktypes> as its value.
Dereferencing that URI yields a profile document that lists all the link relation types that
a client can expect when requesting the link set made discoverable by the "linkset" link.
For posterity that profile document was saved in the Internet Archive at
<https://web.archive.org/web/20210927160406/https://www.gs1.org/voc/?show=linktypes>
on 27 September 2021. shows a client issuing an
HTTP HEAD request against the link set <https://id.gs1.org/01/9506000134352?linkType=all> that was discovered through the HTTP interactions shown in . shows the server's response to the request of . Note the "profile" parameter for the application/linkset+json media type, which has as value the same Profile URI <https://www.gs1.org/voc/?show=linktypes> as was used in <xref target="Response_pr_at"/>.Note that the response from the link set resource is equivalent to the response shown in , which leverages the "profile" link relation type defined in .A link with a "profile" link relation type as shown in can also be conveyed in the link set document itself. This is illustrated by . Following the recommendation that all links in a link set document should have an explicit anchor, such a link has the URI of the link set itself as anchor and the Profile URI as target. Multiple Profile URIs are handled by using multiple "href" members.The link relation type below should be registered by IANA per Web Linking:
Relation Name: linkset
Description: The link target of a link with the "linkset" relation type
provides a set of links, including links in which the link context of the link participates.
Reference: [[ This document ]]
The Internet media type for a natively encoded linkset is application/linkset.
Type name: application
Subtype name: linkset
Required parameters: none
Optional parameters: profile
Encoding considerations: Linksets are encoded according to the definition of . The encoding of is based on the general encoding rules of , with the addition of allowing indicating character encoding and language for specific parameters as defined by .
Security considerations: The security considerations of [[ This document ]] apply.
Interoperability considerations: N/A
Published specification: [[ This document ]]
Applications that use this media type: This media type is not specific to any application, as it can be used by any application that wants to interchange web links.
Additional information:
Magic number(s): N/A
File extension(s): This media type does not propose a specific extension.
Macintosh file type code(s): TEXT
Person & email address to contact for further information: Erik Wilde <erik.wilde@dret.net>
Intended usage: COMMON
Restrictions on usage: none
Author: Erik Wilde <erik.wilde@dret.net>
Change controller: IETF
The Internet media type for a JSON-encoded linkset is application/linkset+json.
Type name: application
Subtype name: linkset+json
Required parameters: none
Optional parameters: profile
Encoding considerations: The encoding considerations of apply
Security considerations: The security considerations of [[ This document ]] apply.
Interoperability considerations: The interoperability considerations of apply.
Published specification: [[ This document ]]
Applications that use this media type: This media type is not specific to any application, as it can be used by any application that wants to interchange web links.
Additional information:
Magic number(s): N/A
File extension(s): JSON documents often use ".json" as the file extension, and this media type does not propose a specific extension other than this generic one.
Macintosh file type code(s): TEXT
Person & email address to contact for further information: Erik Wilde <erik.wilde@dret.net>
Intended usage: COMMON
Restrictions on usage: none
Author: Erik Wilde <erik.wilde@dret.net>
Change controller: IETF
The security considerations of Web Linking apply, as long as they are not specifically discussing the risks of exposing information in HTTP header fields.In general, links may cause information leakage when they expose information (such as URIs) that can be sensitive or private. Links may expose "hidden URIs" that are not supposed to be openly shared, and may not be sufficiently protected. Ideally, none of the URIs exposed in links should be supposed to be "hidden"; instead, if these URIs are supposed to be limited to certain users, then technical measures should be put in place so that accidentally exposing them does not cause any harm.For the specific mechanisms defined in this specification, two security considerations should be taken into account:
The Web Linking model always has an "implicit context", which is the resource of the HTTP interaction. This original context can be lost or can change when self-contained link representations are moved. Changing the context can change the interpretation of links when they have no explicit anchor, or when they use relative URIs. Applications may choose to ignore links that have no explicit anchor or that use relative URIs when these are exchanged in stand-alone resources.
The model introduced in this specification supports "3rd party links", where one party can provide links that have another party's resource as an anchor. Depending on the link semantics and the application context, it is important to verify that there is sufficient trust in that 3rd party to allow it to provide these links. Applications may choose to treat 3rd party links differently than cases where a resource and the links for that resource are provided by the same party.
DCMI Metadata TermsA set of links rendered according to the
JSON serialization defined in can be interpreted
as RDF triples by adding a JSON-LD context that maps
the JSON keys to corresponding Linked Data terms. And, as per section 6.8,
when delivering a link set that is rendered according to the "application/linkset+json" media type to a user agent,
a server can convey the availability of such a JSON-LD context by using a link with the relation type
"http://www.w3.org/ns/json-ld#context" in the HTTP "Link" header. shows the response of an HTTP GET against the URI of a link set resource and
illustrates this approach to support discovery of a JSON-LD Context. The example is inspired by the GS1 implementation and
shows a link set that uses relation types from the GS1 vocabulary at <https://www.gs1.org/voc/>
that are expressed as HTTP URIs.
; rel="http://www.w3.org/ns/json-ld#context"
; type="application/ld+json"
Content-Length: 1532
{
"linkset": [
{
"anchor": "https://id.gs1.org/01/09506000149301",
"https://gs1.org/voc/pip": [
{
"href": "https://example.com/en/defaultPage",
"hreflang": [
"en"
],
"type": "text/html",
"title": "Product information"
},
{
"href": "https://example.com/fr/defaultPage",
"hreflang": [
"fr"
],
"title": "Information produit"
}
],
"https://gs1.org/voc/whatsInTheBox": [
{
"href": "https://example.com/en/packContents/GB",
"hreflang": [
"en"
],
"title": "What's in the box?"
},
{
"href": "https://example.com/fr/packContents/FR",
"hreflang": [
"fr"
],
"title": "Qu'y a-t-il dans la boite?"
},
{
"href": "https://example.com/fr/packContents/CH",
"hreflang": [
"fr"
],
"title": "Qu'y a-t-il dans la boite?"
}
],
"https://gs1.org/voc/relatedVideo": [
{
"href": "https://video.example",
"hreflang": [
"en",
"fr"
],
"title*": [
{
"value": "See it in action!",
"language": "en"
},
{
"value": "Voyez-le en action!",
"language": "fr"
}
]
}
]
}
]
}
]]>
In order to obtain the JSON-LD Context conveyed by the server, the user agent issues an HTTP GET against the
link target of the link with the "http://www.w3.org/ns/json-ld#context" relation type. The response to this GET is
shown in . This particular JSON-LD context maps "application/linkset+json" representations of link sets
to Dublin Core Terms . Note that the "linkset" entry in the JSON-LD context is
introduced to support links with the "linkset" relation type in link sets.Applying the JSON-LD context of to the link set of
allows transforming the "application/linkset+json" link set to an RDF link set. shows
the latter represented by means of the "text/turtle" RDF serialization.
"text/html" .
"en" .
"Product information" .
"en" .
"What's in the box?" .
"fr" .
"Information produit" .
"fr" .
"Qu'y a-t-il dans la boite?" .
"fr" .
"Qu'y a-t-il dans la boite?" .
.
.
.
.
.
.
"en" .
"fr" .
"See it in action!"@en .
"Voyez-le en action!"@fr .
]]>
This section records the status of known implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in RFC 7942 . The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations may exist.According to RFC 7942, "this will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature. It is up to the individual working groups to use this information as they see fit".GS1 is a provider of identifiers, most famously seen in EAN/UPC barcodes for retail and healthcare products, and manages an ecology of services and standards to leverage them at a global scale.
GS1 has indicated that it will fully implement this "linkset" specification as a means to allow requesting and representing links pertaining to products, shipments, assets and locations.
The current GS1 Digital Link specification makes an informative reference to version 03 of the "linkset" I-D,
mentions the formal adoption of that I-D by the IETF HTTPAPI Working Group,
and indicates it being on track to achieve RFC status.
The GS1 Digital Link specification adopts the JSON format specified by the I-D
and mentions future plans to also support the Link header format as well as their respective media types,
neither of which have changed since version 03.The FAIR Signposting Profile is a community specification aimed at improving machine navigation
of scholarly objects on the web through the use of typed web links pointing at e.g.
web resources that are part of a specific object, persistent identifiers for the object and its authors,
license information pertaining to the object. The specification encourages the use of Linksets and
initial implementations are ongoing, for example, for the open source Dataverse data repository platform
that was initiated by Harvard University and is meanwhile used by research institutions, worldwide.Open Journal Systems (OJS) is an open-source software for the management of peer-reviewed academic journals, and is created by the Public Knowledge Project (PKP), released under the GNU General Public License. Open Journal Systems (OJS) is a journal management and publishing system that has been developed by PKP through its federally funded efforts to expand and improve access to research.The OJS platform has implemented "linkset" support as an alternative way to provide links when there are more than a configured limit (they consider using about 10 as a good default, for testing purpose it is currently set to 8).Thanks for comments and suggestions provided by Phil Archer, Dominique Guinard, Mark Nottingham, Julian Reschke, Rob Sanderson, Stian Soiland-Reyes, and Sarven Capadisli.