Re: [Json] JSON Schema Language

[Pete Cordell <[e-mail]>]

On 06/05/2019 23:38, Tim Bray wrote:
> Hi all.  I haven't got around to reading the draft (but will soon).  
> Prior to that, a few notes:
> 
> 1. I'm pretty sure that we need something better than what we have in 
> the area of JSON schemas.  At least, I'm 100% sure that my job at Amazon 
> Web Services would be easier, and our customer experiences would be more 
> pleasant, if we had something.
> 
> 2. One thing schemas are useful for is to syntax-check JSON texts that 
> claim to conform to some language specification or another. Obviously no 
> schema can ever completely satisfy this requirement - there are always 
> things in specifications which are semantic and not addressable by 
> schemas - but they can still be super useful.
> 
> 3. Another thing they are useful for is for providing help to developers 
> working in strongly typed programming languages. With a well-built 
> schema it is reasonably straightforward to auto-generate nice idiomatic 
> class declarations in modern programming languages, and also to build 
> serializers/deserializers that will move data back and forth between 
> JSON blobs and programming-language constructs, or fail in a clean 
> deterministic way if the JSON fails to match the schema.

For me:

4. Person-to-person communication is an important use-case for schemas 
as a way of describing valid formats, either in design documents or 
during brainstorming sessions on whiteboards or personal notes on the 
back of envelopes.

When you do that you want to be discussing JSON rather than also working 
out a convention for defining JSON. Hence the need for something already 
defined that is readily and widely understood.

The human need puts me off a JSON format for this.  It is too long 
winded and, like W3C XML Schema, unnecessarily difficult for humans to 
use. It's why XML Relax NG Compact Syntax was developed.  And why I 
prefer JSON Content Rules JSON-like (but not JSON) syntax.

You can get an idea of a comparison of the two types of specification at:

 
http://json-content-rules.org/drafts/draft-newton-json-content-rules-10-pjc.html#rfc.section.2.3

I my mind, JCR is a clear winner in this situation.

Pete.
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Pete Cordell
Codalogic Ltd
Read & write XML in C++, http://www.xml2cpp.com
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