List of the valid or invalid connections between different entity types

[duncangreene]

Presumably there are checks in place in the Validator tooling that govern what connections are valid between different entity types.

Some (assumed) examples below.

Valid
HVAC/AHU_CSP_DFSS_DX2ZC_ECONZ feeds HVAC/VAV_SD
METERS/EM_PWM measures METERS/LOADTYPE_MECHANICAL
FACILITES/ROOM contains LIGHTING/LT_SS

Invalid
HVAC/AHU_CSP_DFSS_DX2ZC_ECONZ measures HVAC/VAV_SD
METERS/EM_PWM controls METERS/LOADTYPE_MECHANICAL
FACILITES/ROOM has_range LIGHTING/LT_SS
METERS/EM_PWM measures FACILITIES/ROOM

I had a very brief scrape through the code in the repo but couldn't deduce a lookup table of sorts that might yield the above information.

Any ideas?

[shambersafai]

The validators only enforce what is explicitly called out as requirements in the ontology yaml files, i.e. uses fields listed on an abstract type, implement abstracts listed on a canonical type, etc. We'd want to avoid hard coding additional restrictions in the validators that are not obvious rules surfaced to users. If we wanted to add validation for this then we would need to create something like a list of allowable source general types and allowable target general types for each connection type in the connections yaml file itself, then have the validator reference and enforce that. I have not personally had the desire to make such restrictions for the following reasons:

1. These lists would be quite long.
2. These lists would need to be edited any time a new general type is created.
3. Even at the general type level it wouldn't be granular enough to provide fully correct restrictions, i.e. a hot water system would feed a VAV with reheat, but not a cooling only VAV. I cannot think of a feasible way to create restrictions at the full entity type level.

My preference due to these reasons is to leave the connections unrestricted in validation and provide clear enough documentation to guide users to make use of them correctly. Let me know your thoughts.