Remote Access to the Application Server
The presentation layer is a thin client that handles the instructions regarding the interface e.g. to select an employee, to check if all mandatory details have been entered, or to display a message if an incorrect value has been entered.
The processing of the business logic is performed on an application server. This processing retrieves, updates, inserts and deletes data, applies business rules and calculations that require interaction with the database, or may be used from more than one screen.