1. Definitions

Models of interactive information processing systems fall between two boundaries that delimit the client/server model; one boundary is based on a scheme whereby all interactive processing takes place on a computer whose resources are shared by passive workstations, while the other boundary is represented by microcomputers operating in "isolated" mode (figure 1 ).

• In the case of a shared computer doing all the processing, the workstation is made up of a keyboard and a screen, and plays a passive role with regard to processing; it transmits the information entered by the user on the keyboard over the network to the processing computer; Conversely, it receives information from the processing computer via the network and displays this information on the screen;...