Decouple NIEM and XML Schema Simple Types?

[cdmgtri]

Migrated from NIEM/NTAC#43.

NIEM uses the xs and niem-xs namespaces for XML Schema simple types and for CSC versions of those types with the structures attribute group.

The name of the niem-xs namespace makes less sense on the NIEM JSON side. Plus, we need to bind these types differently for JSON since the XML Schema base types are not available. (We can try to simulate them as much as possible with the available JSON types and with patterns and built-in formats.) We also use simple xs types directly for attributes and for some simple type bases.

In NIEM JSON, the following seems little off:

• Element nc:VehicleCMVIndicator has type niem-xs:boolean
• Attribute nc:quantityUnitText has type xs:string

Maybe we rename the niem-xs namespace to something more generic.

• Element nc:VehicleCMVIndicator has type niem-types:BooleanType
• Attribute nc:quantityUnitText has type niem-types:StringSimpleType

And maybe we provide format-specific types or native-types schemas with the utilities.

• For NIEM XML, types:date would be a wrapper for XSD type xs:date
• For NIEM JSON, types:date would be a wrapper for JSON type string with format date.

We'll need to have JSON counterparts for other utility schemas anyway. Something like a structures.xsd and a structures.json in the utilities folder. Maybe we do the same thing and have a types.xsd and a types.json there as well. It gives us a layer of indirection.

Dr. Scott: All our targets use the same base data types.

Christina: Even JSON-LD?

[cdmgtri]

The NTAC decided to leave the types as they are. The CMF-to-JSON Schema transformation does provide patterns and definitions for XML Schema simple types to try to align the allowable range of values consistently between XML and JSON representations.