Re: [Json] JSON Schema Language
Rob Sayre <sayrer@gmail.com> Wed, 29 May 2019 03:54 UTC
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From: Rob Sayre <sayrer@gmail.com>
Date: Tue, 28 May 2019 20:54:30 -0700
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To: Tim Bray <tbray@textuality.com>
Cc: Carsten Bormann <cabo@tzi.org>, JSON WG <json@ietf.org>, Ulysse Carion <ulysse@segment.com>
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Subject: Re: [Json] JSON Schema Language
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On Tue, May 28, 2019 at 8:47 PM Tim Bray <tbray@textuality.com> wrote: > TBH, what I want from a schema system is (a) useful error messages and (b) > ability to drive code generation, classes and serializer/deserializers and > so on. > No problem. If it can drive serializer/deserializers, let's spec out some conformance tests. - Rob > On Tue, May 28, 2019 at 8:40 PM Rob Sayre <sayrer@gmail.com> wrote: > >> On Tue, May 28, 2019 at 8:23 PM Tim Bray <tbray@textuality.com> wrote: >> >>> What do you mean by “Output specification”? >>> >> >> Fair question. I'd say a good example might be the objects transferable >> across postMessage() in browser JavaScript. >> >> >> https://html.spec.whatwg.org/multipage/structured-data.html#transferable-objects >> >> It seems like a deep problem at first, but it isn't. Those message >> formats add Date objects and a few other things, but not that much. >> >> - Rob >> >> >> >> >> >>> On Tue, May 28, 2019 at 8:01 PM Rob Sayre <sayrer@gmail.com> wrote: >>> >>>> I'm not sure this schema language will be productive as a source format >>>> in the long term, but I don't think it will be harmful. So, it's not worth >>>> an objection. The worst case would be that servers claim to conform to this >>>> schema language, but fail to serve schema-conformant JSON in practice. This >>>> seems like the likely outcome, in the absence of an output specification. >>>> >>>> I have to say, I think I am uniquely qualified to raise this point. I >>>> objected to the original JSON Stringify specification, which was something >>>> pretty close to string concatenation, and got it corrected to something >>>> close to its current form. >>>> >>>> If a schema language doesn't provide an output specification, it's >>>> probably not going to work in practice. Best case, it's a standards >>>> checkbox. >>>> >>>> - Rob >>>> >>>> >>>> On Tue, May 28, 2019 at 7:41 PM Tim Bray <tbray@textuality.com> wrote: >>>> >>>>> So Carsten, I am a person who would benefit from a super-simple JSON >>>>> schema langauge; in effect, something like JSL + enums + timestamps. >>>>> Furthermore, as I've said, I'm willing to invest some IETF-work cycles to >>>>> get such a thing, in the event we could interest the community. Do you >>>>> think that doing such a JSL and defining it using established CDDL >>>>> semantics might be a good idea? >>>>> >>>>> Alternately, might we retain CDDL syntax and define a profile/subset >>>>> which would be appropriate for us JSON-only simpletons? >>>>> >>>>> I'm not terribly fussy about mechanisms. >>>>> >>>>> >>>>> >>>>> On Fri, May 10, 2019 at 12:16 AM Carsten Bormann <cabo@tzi.org> wrote: >>>>> >>>>>> On May 10, 2019, at 05:55, Ulysse Carion <ulysse@segment.com> wrote: >>>>>> > >>>>>> > Carsten, >>>>>> > >>>>>> > Do you think that our difference in opinion on CDDL vs JSON Schema >>>>>> > Language may be attributable to a difference in requirements? >>>>>> >>>>>> Hi Ulysse, >>>>>> >>>>>> I’m not even sure we disagree. That was why I became interested in >>>>>> converting between JSL and CDDL. As I was trying to show, CDDL might make >>>>>> a fine presentation language for JSL, and JSL might be a nice “profile” for >>>>>> CDDL that is very simple to process. >>>>>> >>>>>> > It seems to me that your use-case is centered around defining >>>>>> > standards and other complex data requirements. CDDL is, in my view, >>>>>> > unquestionably a better choice for this use-case. In my mind, CDDL >>>>>> is >>>>>> > ABNF for CBOR, and that is undeniably what standards dealing with >>>>>> CBOR >>>>>> > or its near-equivalents require. The existing references, from RFCs, >>>>>> > to CDDL are testament to this. >>>>>> >>>>>> Yes, you are describing the intention correctly. I would add that >>>>>> CDDL has proven as useful for describing pure JSON protocols as for CBOR. >>>>>> >>>>>> Not all JSON/CBOR protocols need the full capabilities of CDDL. For >>>>>> instance, the example in the CDDL spec for RFC 7071 could easily be >>>>>> expressed in JSL, except for two details: reputation-object is not meant to >>>>>> be extensible (reputon is), and there are some value constraints (some >>>>>> values are integers). >>>>>> >>>>>> > But I (and I suspect Tim) am more preoccupied solely with defining >>>>>> the >>>>>> > mundane sorts of messages that come out of JSON event processing and >>>>>> > repetitive JSON APIs. Tim has blogged (see link in my original >>>>>> email) >>>>>> > about dealing with AWS's CloudWatch events. That's messages that >>>>>> look >>>>>> > like this: >>>>>> > >>>>>> > >>>>>> https://docs.aws.amazon.com/AmazonCloudWatch/latest/events/EventTypes.html >>>>>> > >>>>>> > Tons of messages, and frequently being added and updated. But none >>>>>> of >>>>>> > these messages are particularly exciting from a schema perspective. >>>>>> >>>>>> Well, I just had a look at (randomly selected) >>>>>> >>>>>> https://docs.aws.amazon.com/AmazonCloudWatch/latest/events/EventTypes.html#health-event-types >>>>>> You’d need to add enumerations to JSL. There are also timestamps in >>>>>> the object (ironically in two different formats). There is a table that >>>>>> maps language tags to messages in that language. (And the second and third >>>>>> example have a missing bracket.) But I can’t really say, because the >>>>>> description by example only just begins to expose the actual intention. >>>>>> >>>>>> > CDDL can do much more than is necessary for merely representing >>>>>> > CloudWatch events. This may seem like a good thing, but such excess >>>>>> > capability reduces the suitability of the solution. JSON Schema >>>>>> > Language is intentionally small and scuttled in scope, so as to >>>>>> > simplify code and UI generation. By being so limited in scope, JSON >>>>>> > Schema Language fits more easily into the architecture of a system >>>>>> > that would like to integrate it. >>>>>> >>>>>> I’ve seen my share of developments that start simple. How much >>>>>> functionality will be added to JSL before it becomes a standard? Also, the >>>>>> law of extensibility tells us it will be extended even after becoming a >>>>>> standard. >>>>>> >>>>>> Of course, in its domain, CDDL is incredibly simple. Compare to JCR: >>>>>> JCR is about three times as complex as CDDL. This is because CDDL was >>>>>> built from a few very simple building blocks, which combine nicely to >>>>>> provide its functionality. JCR is more of an accretion of features, which >>>>>> in sum can do most of what CDDL can do. >>>>>> >>>>>> But back to JSL and CDDL: >>>>>> What I’m interested in is what are the sweet spots on this >>>>>> functionality vs. complexity continuum. I think we have found two of these >>>>>> sweet spots (at least maybe after a little more calibration). Now how do >>>>>> we handle the onslaught of applications that don’t quite fit the sweet >>>>>> spots? >>>>>> >>>>>> The question that intrigues me: Is it possible to define something >>>>>> that is as simple as JSL when you need just that, but allows dipping into >>>>>> the capabilities of something like CDDL where needed? >>>>>> >>>>>> By the way: You may not be aware of the WISHI activity we have in the >>>>>> T2TRG (thing-to-thing research group) of the IRTF. Here we look at >>>>>> modeling (not just for data) and at translating between different modeling >>>>>> approaches. http://wishi.space if you want to have a look. >>>>>> >>>>>> Grüße, Carsten >>>>>> >>>>>> _______________________________________________ >>>>>> json mailing list >>>>>> json@ietf.org >>>>>> https://www.ietf.org/mailman/listinfo/json >>>>>> >>>>> _______________________________________________ >>>>> json mailing list >>>>> json@ietf.org >>>>> https://www.ietf.org/mailman/listinfo/json >>>>> >>>>
- [Json] JSON Schema Language Ulysse Carion
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] JSON Schema Language Carsten Bormann
- Re: [Json] JSON Schema Language Austin Wright
- Re: [Json] JSON Schema Language Carsten Bormann
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] JSON Schema Language Austin Wright
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] JSON Schema Language Carsten Bormann
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] JSON Schema Language Austin Wright
- Re: [Json] JSON Schema Language Carsten Bormann
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language John Cowan
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] JSON Schema Language Austin Wright
- Re: [Json] JSON Schema Language Carsten Bormann
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] JSON Schema Language Carsten Bormann
- Re: [Json] JSON Schema Language Austin Wright
- Re: [Json] JSON Schema Language Carsten Bormann
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] JSON Schema Language Phillip Hallam-Baker
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Austin Wright
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Austin Wright
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Austin Wright
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Tim Bray
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Peter Patel-Schneider
- Re: [Json] JSON Schema Language Pete Cordell
- Re: [Json] JSON Schema Language Carsten Bormann
- Re: [Json] JSON Schema Language Phillip Hallam-Baker
- Re: [Json] JSON Schema Language Austin Wright
- Re: [Json] JSON Schema Language Erik Wilde
- Re: [Json] JSON Schema Language Phillip Hallam-Baker
- Re: [Json] JSON Schema Language Phillip Hallam-Baker
- Re: [Json] JSON Schema Language Austin Wright
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Erik Wilde
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Ulysse Carion
- Re: [Json] JSON Schema Language John Cowan
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] JSON Schema Language Carsten Bormann
- Re: [Json] JSON Schema Language Pete Cordell
- Re: [Json] JSON Schema Language Pete Cordell
- Re: [Json] JSON Schema Language Carsten Bormann
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Nico Williams
- Re: [Json] JSON Schema Language Erik Wilde
- [Json] Adding integers to JSON (Re: JSON Schema L… Carsten Bormann
- Re: [Json] JSON Schema Language Anders Rundgren
- Re: [Json] Adding integers to JSON (Re: JSON Sche… Nico Williams
- Re: [Json] JSON Schema Language Daniel P
- Re: [Json] Adding integers to JSON (Re: JSON Sche… Nico Williams
- Re: [Json] Adding integers to JSON (Re: JSON Sche… Carsten Bormann
- Re: [Json] Adding integers to JSON (Re: JSON Sche… Austin Wright
- Re: [Json] Adding integers to JSON (Re: JSON Sche… Carsten Bormann
- Re: [Json] Adding integers to JSON (Re: JSON Sche… Phillip Hallam-Baker
- Re: [Json] Adding integers to JSON (Re: JSON Sche… Carsten Bormann
- Re: [Json] Adding integers to JSON (Re: JSON Sche… Phillip Hallam-Baker
- Re: [Json] Adding integers to JSON (Re: JSON Sche… John Cowan
- Re: [Json] JSON Schema Language Ulysse Carion
- Re: [Json] Adding integers to JSON (Re: JSON Sche… Austin Wright
- Re: [Json] JSON Schema Language Carsten Bormann
- Re: [Json] JSON Schema Language Rob Sayre
- Re: [Json] Adding integers to JSON (Re: JSON Sche… Manger, James
- Re: [Json] Adding integers to JSON (Re: JSON Sche… Anders Rundgren
- Re: [Json] JSON Schema Language Phillip Hallam-Baker
- Re: [Json] JSON Schema Language John Cowan
- Re: [Json] JSON Schema Language Tim Bray
- Re: [Json] JSON Schema Language Rob Sayre
- Re: [Json] JSON Schema Language Tim Bray
- Re: [Json] JSON Schema Language Rob Sayre
- Re: [Json] JSON Schema Language Tim Bray
- Re: [Json] JSON Schema Language Rob Sayre
- Re: [Json] JSON Schema Language Pete Cordell
- Re: [Json] JSON Schema Language Nico Williams
- [Json] A minimal examplotron-style JSON validatio… John Cowan
- Re: [Json] A minimal examplotron-style JSON valid… Nico Williams
- Re: [Json] JSON Schema Language Phillip Hallam-Baker
- Re: [Json] A minimal examplotron-style JSON valid… Pete Cordell
- Re: [Json] A minimal examplotron-style JSON valid… Carsten Bormann
- Re: [Json] A minimal examplotron-style JSON valid… Ulysse Carion
- Re: [Json] A minimal examplotron-style JSON valid… Carsten Bormann
- Re: [Json] A minimal examplotron-style JSON valid… John Cowan
- Re: [Json] A minimal examplotron-style JSON valid… John Cowan
- Re: [Json] A minimal examplotron-style JSON valid… Pete Cordell
- Re: [Json] A minimal examplotron-style JSON valid… Nico Williams
- Re: [Json] A minimal examplotron-style JSON valid… John Cowan
- Re: [Json] A minimal examplotron-style JSON valid… Nico Williams
- Re: [Json] A minimal examplotron-style JSON valid… John Cowan
- Re: [Json] A minimal examplotron-style JSON valid… Nico Williams