JSON-LD update DC 2017

JSON-LD Update
State of JSON-LD in 2017
1
Gregg Kellogg
gregg@greggkellogg.net
@gkellogg
http://www.slideshare.net/gkellogg1/jsonld-update-dc-2017

Quite Successful Format
• The October 2016 Common Crawl reports over 2 million
(out of 3 million) HTML pages include JSON-LD [1].
• JSON-LD is one of the formats supported by schema.org,
in addition to Microdata and RDFa [2].
• JSON-LD is a required format in the Linked Data platform
[3].
• JSON-LD is becoming popular for many other REST APIs.
2
[1] webdatacommons.org/structureddata/#results-2016-1
[2] http://blog.schema.org/2013/06/schemaorg-and-json-ld.html
[3] https://www.w3.org/TR/ldp/

Keys to Success
• A primary goal was to allow JSON developers to
use it as if it is normal JSON.
The syntax is designed to not disturb already deployed systems running on
JSON, but provide a smooth upgrade path from JSON to JSON-LD. Since the
shape of such data varies wildly, JSON-LD features mechanisms to reshape
documents into a deterministic structure which simplifies their processing [4].
• JSON-LD allows developers to focus on the JSON,
but modelers to get back to the RDF data model for
semantic analysis and validation.
3
[4] https://www.w3.org/TR/json-ld/

JSON-LD – Key
Features
• Add @context to JSON to associate terms (properties) with
IRIs which define them.
• Describe the expected types for string values of properties
• IRI, Dates, Numbers, …
• Treat collections as lists or sets.
• Encourage the use of well-known identifiers for entities, and
provide typing (@id and @type).
• (much more, see JSON-LD 1.0 for a complete feature set).
4

JSON-LD 1.1
• It’s been over three years since JSON-LD 1.0 was published, and feature requests have been
mounting:
• 36 issues addressed since 1.0 (15 still open)
• Use objects to index into collections, rather than only array form
• Previously restricted to @index and @language. Now available on @id and @type.
• Can include @set with other container types (e.g.: "@container": ["@set",
"@language"]).
• Framing, never complete in 1.0. Now provides ability to match on @id, inclusive or exclusive
@type, property values, and specifics of a value object. Supports framing of datasets, not just
graphs.
• Contexts scoped to terms: property values or entities using a given type term can overlay
terms-specific contexts.
• Ignore some elements of JSON structure.
• Abstract from JSON-itself, allowing for YAML, CBOR and other LD representations.
5

Version Announcement
6
{
"@context":
{
"@version": 1.1,
"schema": "http://schema.org/",
"name": "schema:name",
"body": "schema:articleBody",
"words": "schema:wordCount",
"post": {
"@id": "schema:blogPost",
"@container": "@id"
}
},
"@id": "http://example.com/",
"@type": "schema:Blog",
"name": "World Financial News",
…
}
• For backwards compatibility, version 1.1 must be
specified to use new 1.1 features (may be through API).

@id Maps
7
{
"@context":
{
"@version": 1.1,
"schema": "http://schema.org/",
"name": "schema:name",
"body": "schema:articleBody",
"words": "schema:wordCount",
"post": {
"@id": "schema:blogPost",
"@container": "@id"
}
},
"@id": "http://example.com/",
"@type": "schema:Blog",
"name": "World Financial News",
"post": {
"http://example.com/posts/1/en": {
"body": "World commodities were up today with heavy trading of crude oil...",
"words": 1539
},
"http://example.com/posts/1/de": {
"body": "Die Werte an Warenbörsen stiegen im Sog eines starken Handels von Rohöl...",
"words": 1204
}
}
}

Nested Properties
8
{
"@context": {
"@version": 1.1,
"skos": "http://www.w3.org/2004/02/skos/core#",
"labels": "@nest",
"main_label": {"@id": "skos:prefLabel"},
"other_label": {"@id": "skos:altLabel"},
"homepage": {"@id": "http://schema.org/description", "@type": "@id"}
},
"@id": "http://example.org/myresource",
"homepage": "http://example.org",
"labels": {
"main_label": "This is the main label for my resource",
"other_label": "This is the other label"
}
}

Scoped Contexts
9
{
“@context": {
"@version": 1.1,
"name": "http://schema.org/name",
"interest": {
"@id":"http://xmlns.com/foaf/0.1/interest",
"@context": {"@vocab": "http://xmlns.com/foaf/0.1/"}
}
},
"name": "Manu Sporny",
"interest": {
"@id": "https://www.w3.org/TR/json-ld/",
"name": "JSON-LD",
"topic": "Linking Data"
}
}

Scoped Contexts (@type)
10
{
“@context": {
"@version": 1.1,
"name": "http://schema.org/name",
"interest": "http://xmlns.com/foaf/0.1/interest",
"Document": {
"@id": "http://xmlns.com/foaf/0.1/Document",
"@context": {"@vocab": "http://xmlns.com/foaf/0.1/"}
}
},
"@type": "Person",
"name": "Manu Sporny",
"interest": {
"@id": "https://www.w3.org/TR/json-ld/",
"@type": "Document",
"name": "JSON-LD",
"topic": "Linking Data"
}
}

Improve Compact IRIs
11
• Previously, when compacting, compact IRIs could
be created that were not intended.
• E.g., defining a term “sport” could cause the
creation of a term “sport:sEvent”, where
“schema:sportsEvent” was intended.
• Now, terms only used for creating Compact IRIs if
the term ends with a “:” or the value of the term is
an IRI ending with “/” or “#”.

Open Issues
12
• Add an @graph container type [#195].
• Unmapped JSON values [#333].
• Remove unnecessary use of @graph in framed output
[#435].
• Improve use of language maps with values not having
a language [#480].
• HTTP Request profile to specify compaction context or
frame [#491].

JSON-LD 1.1 Timeline
• All work being done in Community Group [5][6].
• With enough interest, a Working Group could be spun up to create a Recommendation,
and possibly address additional requirements.
• Suggested Plenary for TPAC 2017
• Expect community drafts to complete in Q4 2017 (Please comment to help get approved).
• Ruby implementation conforms to all changes in CG specs.
• Live at Ruby RDF Distiller.
• Changes likely easily applied to Python, Javascript, PHP, Java, C#, Go and other
implementations.
• Still no publicly available implementation in “C”.
13
[5] https://www.w3.org/community/json-ld/
[6] http://json-ld.org

Related Topics for
using JSON-LD
14

Shape Expressions
(ShEx)
• ShEx [7] is used for
validating graph
patterns, similar to,
but less complex then
SHACL.
• JSON grammar is
JSON-LD/RDF.
Also has Compact
Grammar.
15
[7] https://shexspec.github.io/spec
ex:PersonShape {
foaf:name .
}
ex:EmployeeShape {
&ex:PersonShape ;
ex:employeeNumber .
}
{ "type":"Schema", "shapes": [{
"id": "http://schema.example/PersonShape",
“type": "Shape", "expression": {
"type": "TripleConstraint",
"predicate": "http://xmlns.com/foaf/0.1/name"
}
}, {
"id": "http://schema.example/EmployeeShape":,
"type": "Shape", "expression": {
“type": "EachOf", "shapeExprs": [
“http://schema.example/PersonShape",
{ "type": "TripleConstraint",
"predicate": "http://schema.example/employeeNumber" }
]
}
}]
}

Decentralized Identifiers
• The WebDHT [8] proposes to use the block-chain
for as an identifier space with immutable content in
the block chain.
• Content is a JSON-LD document, so may be used
as the target of a @context.
• Content will not change, so may be cached or
distributed out-of-band.
• Content signed to guarantee veracity.
16
[8] http://opencreds.org/specs/source/webdht/

Linked Data Signatures
• Mechanism for signing Linked Data documents [9]
• Part of the work of the Digital Verification Community Group [10]
17
[9] https://w3c-dvcg.github.io/ld-signatures/
[10] https://w3c-dvcg.github.io/
{
"@context": "https://w3id.org/identity/v1",
"title": "Hello World!",
"signature": {
"type": "LinkedDataSignature2015",
"creator": "http://example.com/i/pat/keys/5",
"created": "2011-09-23T20:21:34Z",
"domain": "example.org",
"nonce": "2bbgh3dgjg2302d-d2b3gi423d42",
"signatureValue": "OGQzNGVkMzVm4NTIyZTkZDY...NmExMgoYzI43Q3ODIyOWM32NjI="
}
}

Verifiable Claims
• Close to becoming a
Working group [12].
• Could be a source
of identity for WoT.
• Defines a data model
and syntax for
making claims [13].
18
[12] http://w3c.github.io/vctf/charter/proposal.html
[13] https://opencreds.github.io/vc-data-model/

More Information
19
json-ld.org
github://json-ld.org/json-ld/issues
Gregg Kellogg
@gkellogg
gregg@greggkellogg.net
http://greggkellogg.net/
json-ld.org/spec/latest/json-ld/
json-ld.org/spec/latest/json-ld-api/
json-ld.org/spec/latest/json-ld-framing/

JSON-LD update DC 2017

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