Re: [xml-dev] How to validate JSON against XSD schemas

[Michael Kay <mike@saxonica.com>]

My advice would be to take the data model underlying the XML Schema, then produce a JSON representation of that data model, then create custom transformations between the JSON and XML representations.

If you try to produce any kind of mechanistic conversion of the XML Schema or instances to JSON, the JSON will forever look weird, as if it was designed by XML people who didn't understand JSON. If you want your customers to be able to use JSON instead of XML then you want to make the JSON as usable as possible.

MIchael Kay

Saxonica

On 16 Jul 2018, at 20:43, Piers MacDonald <piers@piersmacdonald.com> wrote:

I know the title sounds impossible, give it a second. We have XSD schemas created by an open-standards industry group. In our service we'd like our customers to be able to use JSON or XML when supplying data. What's the best practice in a situation like this?

1. Convert JSON payloads to XML and validate against the XSD.

2. Convert the XSD to JSON Schema and validate each content-type against it's own schema

3. Convert the XSD to a class-based in language specification and do schema validation in code and then handle content negotiation in the api middleware

4. Secret super option

FWIW, these XSD schemas are not overly trivial: ~4000 lines long, multiple namespaces with a half-dozen common schemas shared between them. Changes are rare (one every 2 years) but new schemas are added much more frequently (10 per year)