Publish information about available commands

[ryan-summers]

It would be beneficial to the end user if there was some information about available commands automatically posted somewhere.

Ideally, wherever this information is posted would be retained so that it's accessible for any client that connects to the MQTT broker.

Ideally, an implementation would:

• Provide accepted command strings
• Indicate expected command format (e.g. JSON schema, or by example)

Such a topic could also be configured to automatically be removed as part of the will, although I am currently unsure if this would be supported via MQTT.

[jordens]

The more I think about it the more I suspect that instead of republishing the settings individually and after backtracking them from state, we may just publish a schema describing them. Could be one JSON chunk derived from the minconf structure and/or the minireq. That would also allow describing possible values, not just keys.

[ryan-summers]

I've been having similar thoughts about this in my free time. While publishing the current settings in miniconf is a good start, it's not a functionally complete approach, since it doesn't describe possible enums etc. Some time of compile-time schema generation would be helpful here, but this needs a bit more thought and investigation.

It would be nice to use JSON schema though, since then we can develop client-side software that can automatically derive available commands and their expected format. This would also make it so that the client-side software never needs to be updated and would be compatible with multiple firmware versions etc.

[jordens]

Yes. That's what I meant.