History - early days

2014 - RDF Working Group

• JSON-LD v1.0
• JSON-LD API v1.0

2018-2020 - JSON-LD WG

• JSON-LD v1.1
• JSON-LD API v1.1
• JSON-LD Framing v1.1 (based on JSON-LD CG work)

History - current WG

2020-2023 (extended to 2025) - JSON-LD WG (maintenance mode)

• JSON-LD v1.1
• JSON-LD API v1.1
• JSON-LD Framing v1.1

2025-2027 - Recharter for new work

• JSON-LD, API, Framing v1.1 (maintain)
• JSON-LD, API, Framing v1.2 (new)
• CBOR-LD (new)
• YAML-LD (new)
• Notes
  • Multiple languages in JSON
  • Content hash provision in context URLs

CBOR-LD

A semantic compression format for JSON-LD

Concise Binary Object Representation for Linked Data

• Enables small data use cases: storage, transfer, constrained encoding (e.g. QR codes)
• Using semantic information from JSON-LD contexts enables powerful compression
• Extensible registry system for self-describing payloads
• Plug-and-play with JSON-LD

CBOR-LD Compression

• Build compression dictionary by processing context files that appear in the JSON-LD
  • Assign terms in contexts integer values that they will compress to
  • Deterministic algorithms: a 2nd party decompressing the payload will construct the exact same term-to-integer map
• CBOR-LD Tag registry allows further compression and self-describing payloads
• Contexts and CBOR tag are the compression dictionary: no need to modify the JSON-LD!

CBOR-LD Registry

• CBOR tag: header for CBOR payload
• CBOR-LD has a range of CBOR tags:
  • Additional precision (optionally) identifies a registry entry
  • Registry entry identifies use case, allows expression of additional compression techniques
  • Decompressor sees the tag, does a registry lookup, retrieves the decompression information
• Result: CBOR-LD payloads self-describing, can get additional compression power beyond context terms if use case requires it

CBOR-LD Compression Table

Map {
    ...
    'EnvelopedVerifiableCredential' => 110,
    'EnvelopedVerifiablePresentation' => 112,
    'JsonSchema' => 114,
    'JsonSchemaCredential' => 116,
    'VerifiableCredential' => 118,
    'VerifiablePresentation' => 120
    ...
  }

Utopia Driver's License VC

{
  "@context": [
    "https://www.w3.org/ns/credentials/v2",
    "https://w3id.org/vc-barcodes/v1",
    "https://w3id.org/utopia/v2"
  ],
  "type": [
    "VerifiableCredential",
    "OpticalBarcodeCredential"
  ],
  "credentialSubject": {
    "type": "AamvaDriversLicenseScannableInformation",
    "protectedComponentIndex": "uggAg"
  },
  "issuer": "did:key:zDnaeWjKfs1ob9QcgasjYSPEMkwq31hmvSAWPVAgnrt1e9GKj",
  ...
}

The term to ID map created by CBOR-LD when compressing a Utopia DL.

Map(97) {
  '@context' => 0,
  '@type' => 2,
  ...
  'VerifiableCredential' => 118,
  ...
  'AamvaDriversLicenseScannableInformation' => 160,
  'OpticalBarcodeCredential' => 164,
  'TerseBitstringStatusListEntry' => 166,
  ...
}

CBOR-LD parameters

registryEntryId: 100
typeTable:
{
  "context":
    {
      "https://www.w3.org/ns/credentials/v2": 32768,
      "https://w3id.org/vc-barcodes/v1": 32769,
      "https://w3id.org/utopia/v2": 32770
    },
  "https://w3id.org/security#cryptosuiteString":
    {
      "ecdsa-rdfc-2019": 1,
      "ecdsa-sd-2023": 2,
      "eddsa-rdfc-2022": 3,
      "ecdsa-xi-2023": 4
    }
}

A CBOR-LD compressed Utopia Driver's License VC

d90664a60183198000198001198002189d82187618a418b8a3189c18a618...

Diagnostic:
1636(
  {
    1: [32768, 32769, 32770],
    157: [118, 164],
    184: {156: 166, 206: 178, 208: 3851559041},
    186: {156: 160, 168: h'75820020'},
    190: 170,
    ...  
  

A Verifiable Credential Barcode (a PDF417) of the Utopia driver's license.

CBOR-LD - Road Ahead

• Added to charter
• CBOR-LD 1.0 Working Draft
• Incorporate other work
  • CBOR-LD 1.0 - primary input from JSON-LD CG report
  • JSON-LD in CBOR - alternate approach previously explored
  • CBL: Compact Encoding of JSON-LD Data using CBOR and Bitmaps for Web of Things - community paper exploring alternative approaches
• Gather WG feedback/contribution/changes

YAML-LD

• Enable human-friendly Linked Data
  • Stay compatible with JSON-LD for easy transformation
• CCG developed spec
• Stable, but needs implementers
• WG picking up to formalize and build test suite

Multiple languages in JSON

• JSON-LD's Value Object pattern expressed "alone"
• encourage implementations of Value Objects
• encourage use in JSON documents that lack `@context`
• create a referenceable spec/note for other specs

Content hash fragment for context URLs

• #hash=
• optionally used by document loaders to verify equality of contexts
• not strictly about HTTP