W3C home > Mailing lists > Public > public-credentials@w3.org > April 2021

Re: JSON-LD (Was:Re: Vaccination Certificate Test Suite)

From: Leonard Rosenthol <lrosenth@adobe.com>
Date: Mon, 26 Apr 2021 13:15:57 +0000
To: Nikos Fotiou <fotiou@aueb.gr>, Manu Sporny <msporny@digitalbazaar.com>
CC: "public-credentials@w3.org" <public-credentials@w3.org>
Message-ID: <MN2PR02MB699255F40B21AA45EF13F6DBCD429@MN2PR02MB6992.namprd02.prod.outlook.com>
Nikos  I am sure others will step in with more specifics, but the general answer is that all of these things exist as a way to enable the various requirements in the JSON-LD spec (https://www.w3.org/TR/json-ld/).  To quote:

In addition to all the features JSON provides, JSON-LD introduces:

  *   a universal identifier mechanism for JSON objects<https://tools.ietf.org/html/rfc8259#section-4> via the use of IRIs<https://tools.ietf.org/html/rfc3987#section-2>,
  *   a way to disambiguate keys shared among different JSON documents by mapping them to IRIs<https://tools.ietf.org/html/rfc3987#section-2> via a context<https://www.w3.org/TR/json-ld/#dfn-context>,
  *   a mechanism in which a value in a JSON object<https://tools.ietf.org/html/rfc8259#section-4> may refer to a resource<https://www.w3.org/TR/rdf11-concepts/#dfn-resource> on a different site on the Web,
  *   the ability to annotate strings<https://infra.spec.whatwg.org/#javascript-string> with their language,
  *   a way to associate datatypes with values such as dates and times,
  *   and a facility to express one or more directed graphs, such as a social network, in a single document.

Many of these are key features of Linked Data technologies such as RDF, which is a key driver behind the LD part of JSON-LD (https://www.w3.org/TR/json-ld/#relationship-to-rdf).


On 4/26/21, 8:06 AM, "Nikos Fotiou" <fotiou@aueb.gr> wrote:
I will begin by apologizing for the dump questions, but I still haven't completely understood JSON-LD. I have two questions regarding https://w3c-ccg.github.io/vaccination-vocab/context/v1/index.json

1) What is the purpose of lines 7-10, i.e.,
        "description": "http://schema.org/description",
        "identifier": "http://schema.org/identifier",
        "name": "http://schema.org/name",
        "image": "http://schema.org/image"
and why these attributes are redefined inside VaccinationCertificate attribute (lines 18-21)?

2)  In various places there is the following line
"@type": "http://www.w3.org/2001/XMLSchema#dateTime"

Firstly, I thought that the @type property would lead to something machine readable so that type checks are automated. Even if this is not the case, http://www.w3.org/2001/XMLSchema#dateTime contains no information about this type. Is there any implicit agreement that this URL corresponds to a "date"? The closest I found by following links was that

But even this, it says: "dateTime uses the date/timeSevenPropertyModel, with no properties except timezoneOffset permitted to be absent." Hence **if** this is the correct type, all the examples are not correct since they do not include the time part, in the `birthDate` attribute which is of that type.

Nikos Fotiou - http://pages.cs.aueb.gr/~fotiou
Researcher - Mobile Multimedia Laboratory
Athens University of Economics and Business

> On 25 Apr 2021, at 7:13 PM, Manu Sporny <msporny@digitalbazaar.com<mailto:msporny@digitalbazaar.com>> wrote:
> TL;DR: A new W3C CCG Capability has been created to  generate weekly NxN
> interoperability test reports for W3C  Verifiable Credential Vocabularies. The
> Vaccination  Certificate Vocabulary is the first test report to benefit  from
> this new capability. An example of the test suite output can be viewed here:
> https://w3id.org/vaccination/interop-reports#Polio
> On 4/8/21 1:29 PM, Manu Sporny wrote:
>> You can view the latest Vaccination Certificate test suite report here:
>> https://w3id.org/vaccination/interop-reports
> With a huge thanks to Andrew Jones, a new release of the Vaccination
> Certificate test suite has been released:
> https://github.com/digitalbazaar/vaccination-certificate-test-suite/
> Improvements include:
> 1. A weekly continuous-integration / continuous-testing
>   automation that tests all known VC HTTP API issuers
>   against all known VC HTTP API verifiers that are
>   passing the test suite. PRs welcome to add other
>   issuers or verifiers. You can see the latest run
>   here:
> https://github.com/digitalbazaar/vaccination-certificate-test-suite/runs/2429248801?check_suite_focus=true#step:9:675
> 2. An option to manually trigger a complete test run
>   and upload the latest report to the interoperability
>   reports website.
> 3. Use of the 2020 Ed25519 cryptosuite to provide
>   compression-friendly input to CBOR-LD:
> https://w3id.org/vaccination/interop-reports#Polio
> 4. Use of the new base32 encoding to alphanumeric QR Codes
>   (ensures QR Codes can be read by a large portion of QR
>   Code reader devices):
> https://w3id.org/vaccination/interop-reports#Polio
> 5. Linkability to examples so that people can link to,
>   and have a good understanding of, what each payload
>   looks like:
> https://w3id.org/vaccination/interop-reports#example-4-polio-vaccination-certificate
> 6. A generalized mocha reporter that is optimized for
>   showing an interop compatibility matrix, which is
>   useful during the W3C Candidate Recommendation phase
>   (to demonstrate NxN interoperability status for
>   various implementations):
> https://github.com/digitalbazaar/mocha-w3c-interop-reporter
> The latest full test report is available here:
> https://w3id.org/vaccination/interop-reports
> -- manu
> --
> Manu Sporny - https://www.linkedin.com/in/manusporny/
> Founder/CEO - Digital Bazaar, Inc.
> blog: Veres One Decentralized Identifier Blockchain Launches
> https://tinyurl.com/veres-one-launches
Received on Monday, 26 April 2021 13:16:14 UTC

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