title: Domain driven design is confusing
body: <p>1) What are the <code>BLL-services</code>? What's the difference between them and <code>Service Layer</code> services? What goes to domain services and what goes to service layer?</p>
  
  <p>2) Howcome I refactor BBL model to give it a behavior: <code>Post</code> entity holds a collection of feedbacks which already makes it possible to add another <code>Feedback</code> thru <code>feedbacks.Add(feedback)</code>. Obviosly there are no calculations in a plain blog application. Should I define a method to add a <code>Feedback</code> inside <code>Post</code> entity? Or should that behavior be mantained by a corresponing service?</p>
  
  <p>3) Should I use <code>Unit-Of-Work</code> (and <code>UnitOfWork-Repositories</code>) pattern like it's described in <a href="https://rads.stackoverflow.com/amzn/click/com/0470292784" rel="nofollow noreferrer" rel="nofollow noreferrer">http://www.amazon.com/Professional-ASP-NET-Design-Patterns-Millett/dp/0470292784</a> or it would be enough to use <code>NHibernate ISession</code>?</p>