Browse Prior Art Database

Data Stream Queue to Simulate Contention Error Capability

IP.com Disclosure Number: IPCOM000113795D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 84K

Publishing Venue

IBM

Related People

Kiel, HG: AUTHOR [+2]

Abstract

Described is a Personal Computer (PC) emulator which emulates a non-programmable terminal that simulates contention error processing. Host data streams can be suspended when the message line is in use (simulating a contention error) and processed later when the user presses the Reset key (simulating a contention error being resolved).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Data Stream Queue to Simulate Contention Error Capability

      Described is a Personal Computer (PC) emulator which emulates a
non-programmable terminal that simulates contention error processing.
Host data streams can be suspended when the message line is in use
(simulating a contention error) and processed later when the user
presses the Reset key (simulating a contention error being resolved).

      A Non-Programmable Terminal (NPT) can communicate with a host
computer system through a Work Station Controller (WSC).  The WSC can
communicate with the host using a SNA protocol and host data streams.
The host data stream may allow an application to define which line of
the display screen should be the "error message line".  On some NPTs,
the default error message line may be a separate message line, below
the host display screen.  The host data stream may allow an
application to write a one line message to the error message line.

      When a message is on the display screen (the message line is in
use), the only valid keystrokes are Reset and Help.  When the user
presses the Reset key, the message is removed and the user can again
type data into entry fields.  Note: if the WSC detects a keystroking
error, an error message is written by the WSC to the message line.

      The host SNA component may retain a copy of the last host data
stream sent to a WSC for a NPT.  If the WSC receives a host data
stream and the message line is in use on the host display screen
(either because of a host data stream or a keystroking error), then
the WSC will reject the host data stream with a "Contention Error".
The contention error indicates that the session is temporarily
unavailable.  The host SNA component receives the contention error.
When the user presses the Reset key, which makes the message line
not-in-use, the WSC informs the host SNA component that the
"Contention Error Was Resolved".  Then, the host SNA component...