question: Support custom properties in the processing schema

[sbliven]

We have a number of use cases where adding additional properties would be useful. For instance, some facilities may want to include some parameter for internal use. Such parameters would generally be ignored by any tools accepting OSC-EM as input. "Open schema" technologies like OWL and JSON-LD treat all data this way. However LinkML prefers "closed" schemas which prohibit additional properties.

Official support for open schemas is proposed in linkml/linkml#2241, but no implementation is available. JSON Schemas always seem to set additionalProperties: false for any class other than linkml:Any.

#13 introduces the Descriptor class to provide arbitrary key/value pairs, but this causes errors when generating the schema (@lolasanchezzz, can you add more details?).

How should we deal with this limitation?

• accept OSC-EM as a closed schema and don't use custom descriptors
• hack our JSON-Schema output to set additionalProperties: true
• redefined Descriptor somehow to fit the linkml limitations (how?)

[lolasanchezzz]

The thing is that I did encounter errors within the Descriptor class because there is currently no proper way to allow additional properties in LinkML. Even setting its range to Any didn’t work, as LinkML does not support open schemas in this way.

I still believe Descriptor is a good approach to introduce some flexibility in schema definitions. I'm actively exploring possible workarounds, but since the community is requesting official support for additionalProperties: true in LinkML, I would suggest keeping the Descriptor implementation commented in the scripts until an official solution is available. This way, we acknowledge the need for flexibility without introducing errors in schema generation.

I’ll keep investigating and update here if I find anything useful!