TERMINAL DEVICE SESSION MANAGEMENT PROTOCOL

摘要

72896-3 An improved system for transferring information between a host system and a terminal system in a digital data processing system is described. The new system includes a host computer system which runs application processes and a terminal system which is connected to the host computer system over a communications link. The terminal system includes one or more virtual terminals each of which allows an operator to enter information for use by the application processes and allows output information from the processes to be displayed. The association between a terminal device and an application process is a session. Initially, a session is selected by means of a command transferred over the communications link. Thereafter, information, associated with the selected session, may be transferred over the communications link. This may continue until another session is selected. Command packets may be multiplexed with the information to be transferred to control other sessions without selecting another session. The new information transfer system minimizes the amount of control information which is required to identify the particular session with which data being transmitted over the communications link is associated. This is because once a session is selected, it remains selected until another session is selected, after which the data transmitted is associated with the newly selected session. Since the amount of time control information must be sent is minimized, the amount of time available to send data is maximized.