Hi Daniela,
My understanding (And it is only that) is that it is dividing your
functionality into three separate catagories.
i.e. User Interface, Business Logic and DataTransport.
The BL and /or the DT could be separate assemblies but it is not mandatory.
To me it is more about the functionality of the classes that make up the
application.
So...
I usually put all my Database accesses in one class.(DT)
The Business Layer consists of whatever classes are required to make the
application perform its function(s) eg a Widget class is a business layer
object.
Business layer objects interact with the database by having an instantiation
of the DT class.
The UI instantiates and manipulates business layer objects.
eg A widget maintenance application. based on a Database
DT Class contains methods for
WriteNewWidget
GetWidgetList
Business Layer contains
Class Widget
Class Factory (Which has a collection of Widgets)
UI Layer
Form instantiates a Factory object and has a list box which displays the
Factory's Widget Collection.
FWIW
Bob
"Daniela Roman" <da**********@rogers.comwrote in message
news:uZ**************@TK2MSFTNGP05.phx.gbl...
can someone explain to me please how to develop a 3-tier project?
Is each of the layers parta of a different dll (class library) project?
Thank you