Browse Prior Art Database

3270 Data Stream Performance Improvement

IP.com Disclosure Number: IPCOM000105470D
Original Publication Date: 1993-Aug-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 121K

Publishing Venue

IBM

Related People

Mathewson II, JM: AUTHOR

Abstract

One of the critical resources in the exchange of information is the transmission media that is used to move the information from an application to a user and vice versa. Because of this, a number of different schemes to reduce the amount of data being transmitted have been developed. The following are some examples of how this has been addressed in the past.

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

3270 Data Stream Performance Improvement

      One of the critical resources in the exchange of information is
the transmission media that is used to move the information from an
application to a user and vice versa.  Because of this, a number of
different schemes to reduce the amount of data being transmitted have
been developed.  The following are some examples of how this has been
addressed in the past.

     In the original 3270 Data Stream definition, the suppression of
     nulls on and inbound read modified operation was an initial
method
     to reduce transmission traffic.

     Format Storage enabled applications to transmit data once that
     could be used subsequently many times over.

     This disclosure addresses further techniques to reduce the
transmission traffic of a 3270 Data Stream.  it is based on studies
done of actual 3270 Data Streams.

     It has been determined that a large number of Set Buffer Address
(SBA) orders only reposition the next write location less than 64
bytes from the current write location.  The following makes use of
this information.

     The 3270 architecture defines two bytes following an SBA, Repeat
to Address (RA), and Erase Unprotected to Address (EUA) orders for
addressing.  The address byte interpretation is determined by the two
high orders bits of the first address byte.  The current definition
of the two high order bits of the first address byte used B'00' to
indicate a 14-bit address and B'01' and B'11' to indicate an encoded
12-bit address.  the bit combination B'10' is rejected if received as
an invalid address.

     Therefore, we can take B'10' to indicate a 6-bit increment/count
and only a single byte of address is sent instead of two.

     In existing 3270 data streams, the repeat to address order is
used extensively to repeat either NULLS ('00'X) or BLANKS ('40'X).
Therefore, it would be advantageous to not have to indicate what
character should be repeated if you could designate what character
should be repeated once for the entire data stream.

     This function is provided by the following method.  To the SET
ATTRIBUTE (SA) order add a TYPE VALUE of '3C'X, which will define the
character that should be repeated following the RA order.

     The default state is "FF'X which indicates that the character to
be repeated must be included in the order sequence.  The value
remains in effect until another SA with TYPE '3C'X changes it.  A
Write-type command resets this value to default state.

The following example may help.  Assume the data stream is:

          F5063C0005D1283CE23C000...