US 4,791,566 AGranted

Terminal device session management protocol

AssigneeDigital Equipment Corporation

InventorsRam Sudama, Thomas C. Porcher, Jerrold S. Leichter

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Abstract

The invention provides a new and improved system for transferring information between a host system and a terminal system. A digital data processing system includes a host computer system which runs processors and a terminal system which is connected to the application host computer system over a communication link. The terminal system includes one or more virtual terminals each of which allows an operator to enter information and allows output information 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 communication link. This may continue until another session is selected. This 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. 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.

Claims23

Dependent claims

A session management link for interconnecting a host system having at least one application process to a terminal system having at least one virtual terminal, thereby to effect the transmission of information between a selected virtual terminal and a selected application process, said link including:

A. communications link means between said host and terminal systems for transferring information therebetween;
B. host system session management facility means connected between said application processes and said communications link for transmitting information from said application processes over said communications link, and for generating a plurality of terminal session management commands and transmitting said terminal session management commands over said communications link, one type of said terminal session management command comprising a terminal select session command, each said terminal select session commands identifying a selected interconnection to a virtual terminal;
and
C. terminal system session management facility means connected between said communications link and said virtual terminals for receiving said information and said terminal session management commands transmitted from host system session management facility over said communications link, and continually directing to the selected virtual terminal all said information sent after a terminal select session command is received until a next different terminal select session command is received, so that a single terminal select session command directs all of said following information received by said terminal system session management facility means to the selected virtual terminal until said next different terminal select session command for directing said information to a different selected virtual terminal is received.

1 more element

A method of establishing a session management communications link for interconnecting a host system having at least one application process to a terminal system having at least one virtual terminal, the host system and terminal system connected by a communications link extending therebetween, whereby exchange of information is effected between a selected application process and a selected virtual terminal, said method including the steps of:

transmitting information from the application processes over the communications link by means of a host system session management facility connected between the application processes and the communications link;
transmitting terminal session management commands over the communications link from said host system session management facility, one of said terminal session management commands comprising a terminal select session command, each said terminal select session command identifying a selected interconnection to a virtual terminal;
receiving said information and terminal session select session command from said communications link by means of a terminal system session management facility connected between the communications link and the virtual terminal;
and
said terminal select session command continually directing all of the information received following a terminal select session command to the selected virtual terminal, until a next different terminal select session command is received, so that a single terminal select session command directs all of the following information to said selected virtual terminal until said next different terminal select session command for directing said information to a different selected virtual terminal is received.

2 more elements

Dependencies are inferred from the claim text.