OO Design for Business Logic

Question

I have one Sell Operation object and two Buy Operation objects, I want to implement such a behavior that one Sell operation performs two Buy operations, it looks like this:

sellOperation.Discharge (oneBuyOperation);
sellOperation.Discharge (twoBuyOperation);

so I want to ask if I should call the repository function in the "discharge" method, or should I call the method of saving the repository outside the "Unload" method. as:

opRepository.Save (sellOpertion);

So, can anyone give me some advice on what you are going to implement in this scenario? using a service class or something better?

Answer 1

- - .

, , oneBuyOperation , BuyOperation. , , .

, "", sellOperation "", , .

using(UnitOfWork.Start())
{
    sellOperation.Discharge(oneBuyOperation);
    sellOperation.Discharge(twoBuyOperation);  

    UnitOfWork.CurrentSession.Save(sellOperation);
}

.

Answer 2

.

, Sell object Discharge(). :

sellOperation.Discharge();

http://en.wikipedia.org/wiki/Observer_pattern
http://www.dofactory.com/Patterns/PatternObserver.aspx