Collections as part of other entities

[fennibay]

Today rec:Collection (its subclass brick:Collection) can only be isPartOf Collections and no other entities (e.g. rec:Space, brick:Equipment).

We have certain scenarios where we would like to logically group entities in Collections, where:

• they do not represent a meaningful domain entity such as an equipment, zone etc.; but just a grouping of underlying entities
• they are not at top-level, but within a given context (rec:Space, brick:Equipment).

Some examples:

• CdnMsgCol: Is a collection of condensation message points within a Supply Air VAV.
• Separating different disciplines within a room: HVAC, Lighting, Shading. See RHvacCoo, RLgtCoo, RShdCoo at https://nas.desigo.tw/NGA/Help/en/en-US/10454554635.html
• Organizational "folders" in building automation projects for example for separating room automation from primary automation plants within a building.

So, I propose to extend the properties

• hasPart: allow Collection in the range
• isPartOf: allow Collection in the domain.

This might be better addressed at https://github.com/RealEstateCore/rec. Please advise.

See also: #671

/cc @ektrah

[fennibay]

I had another look at this, with the additions of #724.

Summary of the options:

Option	Description	Pros	Cons
O0	Use collections as generic folders (initial proposal)	(1) Does not introduce parallel hierarchies (2) Covers the collections under zone case	Brick doesn't intend Collection to be used directly, it is an abstract class
O1	Use the PointGroups from #724 in parallel to reflect such hierarchies	(1) No additional changes to Brick (2) Covers grouping entities under Zones	Parallel hierarchies are hard to maintain and interpret
O2	Convert such collections to generic Equipment	Would work with today's model	(1) Logical collection is not actually a physical piece of equipment (2) Doesn't cover the collections under zone case
O3	Flatten such collections	Would work with today's model	We lose the grouping information
O4	Introduce a new subclass under Collection, similar to PointGroup	(1) Does not introduce parallel hierarchies (2) Covers the collections under zone case