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Some things that might help with PROPOSAL regarding JSON-LD material

From: Telford-Reed, Nick <Nick.Telford-Reed@worldpay.com>
Date: Wed, 10 Feb 2016 17:31:31 +0000
To: "public-payments-wg@w3.org" <public-payments-wg@w3.org>
CC: 'Ian Jacobs' <ij@w3.org>, Manu Sporny <msporny@digitalbazaar.com>
Message-ID: <F83606EEAA40AC4EA2919143B15B74C189CC8AC6@UKDC2-PC-MBX03.worldpay.local>
Hello All

If, like me, you have not spent the last several years deeply involved in web and browser specifications but come from the payments industry, you might (like me) find the debate around JSON-LD difficult to follow.

I have found the following resources (starring our very own Manu Sporny) to be useful introductions to the technology in question. If you have 30 minutes, then I heartily recommend:

An introduction to linked data: http://www.youtube.com/watch?v=4x_xzT5eF5Q 
An introduction to JSON-LD: http://www.youtube.com/watch?v=vioCbTo3C-4

I feel like I have at least a grounding in these technologies now, which is helpful.

I'm sure the group will have its say tomorrow on the virtues on JSON-LD and on this proposal.  My own very high level summary is as follows:

PRO: JSON-LD has some very attractive features especially in the extensibility of our work. In particular, I find the idea of defining contexts for any given payment instrument to be quite compelling, rather than tying many different ways of paying to a pre-determined syntax and API. JSON-LD is also a W3C recommendation http://www.w3.org/TR/json-ld/ 

CON: JSON-LD is still emerging as a technology for API development and I think there are concerns (which should be voiced)  about the degree to which introducing JSON-LD to the payments API may make implementations more daunting to the developer community and/or cause friction for adoption

I am about to send out an agenda for tomorrow where we will discuss this further.

Please feel free to weigh in.  This is everybody's group and I'd love to hear from as many voices as possible. 

Nick Telford-Reed
e: nick.telford-reed@worldpay.com | m: +447799473854 | t: +44 203 664 5069

> -----Original Message-----
> From: Ian Jacobs [mailto:ij@w3.org]
> Sent: 10 February 2016 15:05
> To: Manu Sporny
> Cc: public-payments-wg@w3.org
> Subject: Re: PROPOSAL regarding JSON-LD material
> [snip]
> >> ======== PROPOSAL
> >>
> >> * In the base API specification(s), JSON (1) is the message format
> >> required for conformance.
> >
> > Conformance in the Browser API specs (I'm assuming that's what you
> > mean by "base") require a ECMAScript Object matching the interface
> > and/or dictionary definitions. None of the current specification
> > proposals establish JSON as the message format required for conformance.
> The payment request spec has a dependency [1] on ECMA-262 6th Edition
> that seems to refer to JSON objects, and I see statements that say “if not a
> JSOn object then it’s an error.” There are also JSON-looking examples in that
> spec.
> So that’s what I’m referring to. My main point is to say that there is strong
> agreement to use JSON when we need to exchange relevant data, and there
> is not strong agreement to use JSON-LD.
> [1]
> http://wicg.github.io/paymentrequest/specs/paymentrequest.html#depen

> dencies
> >
> >> I believe this requirement is uncontroversial.
> >
> > I don't know if you're saying JSON is the base message format in the
> > Messages spec, or if you're saying JSON is the base message format in
> > the API spec. I'd be a -1 for either proposal.
> >
> > I'd be a +1 for the use of WebIDL to express a message format in the
> > browser API specs as long as there is a clear extensibility story with
> > the use of JSON-LD. This is what the Web Payments CG proposal has been
> > modified to do at this point. We can tweak it here and there, but it's
> > good enough right now for us to focus our efforts on the high-level
> > Checkout API / low-level Payment API.
> >
> >> Still for discussion within the WG:
> >>
> >> - What is the behavior of conforming processors when they encounter
> >> unrecognized properties? I am hearing most support for "leave them
> >> and their values untouched."
> >
> > +1
> >
> >> - What is the behavior of conforming processors when they encounter
> >> unrecognized values of recognized properties? Is the answer "throw an
> >> error" and we define that error handling? or ignore them?
> >
> > Unfortunately, I think the only rational answer at this point is "it
> > depends, but throw an error for the cases where we clearly know there
> > is an error". So this is a case where we clearly know there is an error:
> >
> > FinancialAmount {
> >  "amount": "4f.00",
> >  "currency": "USD"
> > }
> >
> > but here, it's a bit fuzzier:
> >
> > FinancialAmount {
> >  "amount": "0.0024",
> >  "currency": "BTC"
> > }
> >
> > ... and we may not want the browser throwing errors w/ financial
> > amounts at all, instead passing it through to the payment processor to
> handle.
> > In some cases, we may even want to pass it through to the payment
> > processor and in other cases we may not want to do that.
> It seems we need to have more discussion about error handling in the spec;
> that’s fine.
> >
> >> * The Working Group SHOULD publish a companion specification that
> >> explains how to use JSON-LD with the API.
> >
> > That companion specification MUST contain normative language on how
> > you interpret the messages as JSON-LD in order to ensure interoperability.
> > There MUST be a normative link between the API spec and the companion
> > specification.
> >
> >> * If the Working Group publishes a companion specification, the base
> >> API specification(s) SHOULD include a short, informative reference to
> >> that specification. (e.g., with a sentence like "For information
> >> about using JSON-LD with this API, see [OtherSpec].”).
> >
> > -1 for informative. +1 for normative, with language like this:
> >
> > """
> > If an object in this API is to be interpreted as JSON-LD, the rules in
> > COMPANION_SPEC MUST be used to ensure proper message
> interoperability
> > with this API and systems that use JSON-LD-based payment messages.
> > """
> >
> > If you don't have that in there, there is no normative statement on
> > how you use the API objects w/ JSON-LD. I'd be strongly opposed to
> > anything that doesn't ensure interoperability. Clearly, we want to
> > keep the options open, but not so open that it prevents widespread
> interoperability.
> I believe we do not have enough information to determine that a JSON-LD
> specification will lead to interoperability. That is why I favor publishing
> material to start that discussion, then taking the necessary time to work with
> the ecosystem to develop that interoperability. That work should not affect
> the timeline of the browser API.
> I want that work to happy, but do not feel there is a benefit to stronger
> language at this time.
> >
> >> * It gives visibility to the use of JSON-LD with the API. I do not
> >> yet have a sense of "how normative" that companion specification
> >> should be, and therefore this proposal does not address the content
> >> and normative status of that specification. By decoupling the JSON-LD
> >> specification, it can evolve independently as the group sees most
> >> fit.
> >
> > My concern is that we're marginalizing the importance of JSON-LD to
> > the extensibility story without the group fully understanding why
> > we're suggesting JSON-LD is a good solution to the extensibility story.
> I think everyone agrees that the API should enable the exchange of custom
> data.
> I do not believe we have consensus today that there is only one way to
> exchange custom data.
> It is therefore inappropriate to mandate a single approach at this time.
> I do support saying “When you use JSON-LD for custom data, do so like this.”
> and describing that in the companion spec.
> > I'm
> > unconvinced that the group understands why this is important to the
> > interoperable/extensible ecosystem we're trying to build and we're
> > going to prematurely marginalize a key technology as a result of the
> > group not understanding what the proposal in front of them means.
> >
> >> * It keeps the base API specification(s) focused on requirements for
> >> implementers of the defined API. It will also shorten that
> >> specification.
> >
> > We're talking about the difference of a few sentences, I don't think
> > length is an issue here.
> >
> > I'm fine w/ pointing to an external spec as long as:
> >
> > * The link is specific and normative ("if you want to interpret as
> > JSON-LD, follow these rules”).
> I believe that level of mandate is premature.
> > * The external spec is normative.
> That can be determined later once we have more information.
> >
> >> * I would like to see work on the companion specification begin soon
> >> so that we can start to engage with stakeholders in the ecosystem.
> >
> > Is that companion specification the Messages specification? If so,
> > we've already started it here:
> >
> > http://web-payments.github.io/web-payments-messaging/

> >
> > Also note that we can pull in ISO20022 much more easily if we use
> > JSON-LD (as the separation between data model and syntax is the same).
> > That is not true for JSON (where the data model is bound to the syntax).
> >
> >> stakeholders in the ecosystem
> >
> > We should note that Dan Brickley from Google has stated that they're
> > seeing JSON-LD published on millions of websites[1]
> While I am thrilled to hear that JSON-LD has traction, I believe that the use of
> JSON-LD in schema.org is a different use case from what we are talking about
> in the browser API. I do not believe that the data from schema.org is directly
> relevant, though it is certainly good to see adoption in other contexts.
> > and Omar Khan from
> > Wells Fargo has asked us[2] to keep JSON-LD in the spec as a
> > recommended extensibility mechanism (because they'd like to use it).
> I have had several conversations with the people doing the FIBO work and
> they do seem enthusiastic about semantic web technology. That is not a
> sufficient condition to say that we should mandate JSON-LD today. It is
> definitely a piece of what I believe is necessary work to understand the
> interoperability needs and expectations of the ecosystem where this API will
> be used.
> Ian
> >
> > -- manu
> >
> > [1]https://github.com/w3c/webpayments/issues/27#issuecomment-

> 179207196
> > [2]https://lists.w3.org/Archives/Public/public-payments-wg/2016Feb/015

> > 4.html
> >
> > --
> > Manu Sporny (skype: msporny, twitter: manusporny, G+: +Manu Sporny)
> > Founder/CEO - Digital Bazaar, Inc.
> > blog: Web Payments: The Architect, the Sage, and the Moral Voice
> > https://manu.sporny.org/2015/payments-collaboration/

> >
> --
> Ian Jacobs <ij@w3.org>      http://www.w3.org/People/Jacobs

> Tel:                       +1 718 260 9447

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Received on Wednesday, 10 February 2016 17:32:00 UTC

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