Hi Liviu
I am one of the "3 trier" guys.
In my specification I have some thing like :
The following are the "top level" features that must be implemented:
A client program with a graphical user interface that connects to the database
A data access system that provides record locking and a flexible search mechanism
Network server functionality for the database system
So : 1.presentation layer (the GUI), 2.Service layer (Network functionality) and 3.Data Access Layer, so as you can see we have only four layers here
The lock/unlock and them visibility on the client side is a client (side) decision. I choose to hide them - this have advantages and disadvantages - and I document my decision. I think that there is no perfect solution, at the end is just a question of identify the problems, take the decisions and
justify them.
Regards M
SCJP, SCJD, SCWCD, OCPJBCD