Browse Prior Art Database

5250 Read Modified Immediate Alternate Command

IP.com Disclosure Number: IPCOM000119223D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Eagen, ST: AUTHOR [+4]

Abstract

Described is an extension to 5250 display data stream architecture. The Read Modified Immediate Alternate command is a new type of immediate read command that reduces the amount of field data returned to the host system. This reduction in data transmission improves system response time, particularly on remote displays.

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This is the abbreviated version, containing approximately 52% of the total text.

5250 Read Modified Immediate Alternate Command

      Described is an extension to 5250 display data stream
architecture.  The Read Modified Immediate Alternate command is a new
type of immediate read command that reduces the amount of field data
returned to the host system.  This reduction in data transmission
improves system response time, particularly on remote displays.

      It is common for AS/400* systems to communicate with IBM
System/ 370* (S/370) systems and for AS/400 display users to pass
through to a host S/370 system to run S/370 applications.  This is
supported by an AS/400 operating system component called 3270 Device
Emulation (3270DE).

      The flow of data in this type of user environment is
illustrated in the figure.

      In this environment, the AS/400 acts like a remote work station
controller (WSC) to the S/370.  The S/370 application communicates
with 3270DE via a 3270 data stream. 3270DE translates this data
stream into a 5250 data stream when sending data outbound to the WSC
and vice versa when transmitting data inbound to the S/370 host.
This data stream translation enables the AS/400 user to execute S/370
applications.

      3270DE often performs immediate reads of input field data when
screen updates are requested by the host S/370 application.  An
immediate read command is a request to return all field data to the
host immediately, without waiting for the operator to press a
function key.  Immediate reads often cause large amounts of field
data to be transmitted inbound from the WSC, which degrades response
time, particularly if a remote WSC is involved.

      The Read Modified Immediate Alternate (RMIA...