Ah, but now I understand your need better. I was thinking more in the direction of internal organizational purposes, but yes, if you wanted to show your products on a webshop while not maintaining them in two places I understand the need for a hierarchy. But this is more about presentation and should be separate (in my opinion) from the assembly-part-endproduct functionality.
Anyway, my goal is to expand coreBOS, not to connect to other applications. From my experience with building the connector for Exact Online I've learned that (except for very special needs) it's best to keep it all in one app. Since coreBOS is modular and has many entry points to easily build new functionality this really isn't that hard. The hardest thing is establishing what it needs to do, not how to build that. For instance, product hierarchy could be a module where you define separate hierarchies. In the installation script you'd define a new block or field in products where a user can select a hierarchy(position) previously built in the hierarchy module. Then when your webshop connects to coreBOS via the webservice, it could also send this hierarchy information and your webshop could in turn use this to build its presentation. That's just from the top of my head.
Anyway, my goal is to expand coreBOS, not to connect to other applications. From my experience with building the connector for Exact Online I've learned that (except for very special needs) it's best to keep it all in one app. Since coreBOS is modular and has many entry points to easily build new functionality this really isn't that hard. The hardest thing is establishing what it needs to do, not how to build that. For instance, product hierarchy could be a module where you define separate hierarchies. In the installation script you'd define a new block or field in products where a user can select a hierarchy(position) previously built in the hierarchy module. Then when your webshop connects to coreBOS via the webservice, it could also send this hierarchy information and your webshop could in turn use this to build its presentation. That's just from the top of my head.