Hi...yes, GetOrders exists (for real) in domain 'B'. All domain 'A' has is the interface, so that's what it works against. Domain 'A' doesn't "care" about what's in 'B'....just that you pass it an account ID integer, and you get back a set of orders.
Fundamentally, it's just like setting up an API (and, of course, the 'I' stands for interface)
Thanks for reminding me, I gotta get my butt in gear and get that blog updated!
Kevin