Bounded Context, Subdomains and Ubiquitous language

Question

a) With BCs containing two or more subdomains there's a possibility of concepts overlapping and even worse, the same concept ( used by several of these subdomains ) may be interpreted/understood differently by each subdomain.

Regardless, if BC does contain numerous subdomains, should it provide several Ubiquitous languages, one for each subdomain, or should all subdomains share the same Ubiquitous language?

b) I assume when a single subdomain spans several BCs, each of these BCs should define its very own Ubiquitous language?

thanks

Answer 1

a) Although each domain and sub-domain may have its own language, the UL specifically targets the BC. A BC models the domain and barrows as much as possible from the already established domain language. It is called ubiquitous because it is used ubiquitously by the engineers and the domain experts, which unfortunately often cannot be said for the domain language itself.

B) Each BC should have its own UL.

When the BC models more than one (sub)domain with overlapping concepts it would be wise to consider splitting that BC. A shared kernel could be used to deduplicate the overlap that is equal in concept in both (sub)domains.