Communication between BLL and DAL

Question

Solution setup:

• DAL (class library)
• BLL (class library)
• Common (class library (some common functionality - enums, logging, exceptions,...))

Answer 1

Pushing the domain entities into the dal is an option that would remove the crcular dependency, but may not match your intent. This isn't unheard of, though; for example LINQ-to-SQL gnerated entities would live in the DAL.

Other options:

• put them into a common lower assembly (but that may leave your BL rather empty)
• use IOC to remove / reverse the reference between BL/DAL

There are no single right answers here.

Re DataTable; personally I agree - I'm not a fan ;) However, they can be used successfully and reasonably. But if I had to use them, I'd be keeping them in the DAL as an implementation detail - and not exposing them above that.