Browse Prior Art Database

Automated Coordination of SRPI And HLLAPI Communications

IP.com Disclosure Number: IPCOM000100326D
Original Publication Date: 1990-Apr-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 4 page(s) / 138K

Publishing Venue

IBM

Related People

Allen, MJ: AUTHOR [+4]

Abstract

Two common usages of PC-DOS-based personal computers in conjunction with CMS-based host computers are: o A PC-DOS program uses an API in the PC-DOS machine's 3270 terminal emulator to send 3270 terminal keystrokes to an attached CMS host and read 3270 terminal screens from the host. This API is called the High-Level Language Application Programming Interface, or HLLAPI. The PC-DOS program is essentially performing programmed operator function -- it is acting as a programmed typist in order to automate or simplify the PC-DOS user's interaction with CMS.

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

Automated Coordination of SRPI And HLLAPI Communications

       Two common usages of PC-DOS-based personal computers in
conjunction with CMS-based host computers are:
o    A PC-DOS program uses an API in the PC-DOS machine's 3270
terminal emulator to send 3270 terminal keystrokes to an attached CMS
host and read 3270 terminal screens from the host.  This API is
called the High-Level Language Application Programming Interface, or
HLLAPI.  The PC-DOS program is essentially performing programmed
operator function -- it is acting as a programmed typist in order to
automate or simplify the PC-DOS user's interaction with CMS.

      A PC-DOS program uses an API in the terminal emulator to send a
resource access request to a CMS-resident service program and receive
a response from that service program.  This API is called the
Server-Requester Programming Interface, or SRPI. Communications
software components in the terminal emulator and the CMS host use the
3270 terminal connection to convey the ser     vice request and the
service reply.  The PC-DOS program is unaware that data communication
is taking place or that the 3270 terminal emulation connection is
being used as a carrier.

      Prior to this invention, automatic interleaving of access to a
CMS host by a PC-DOS HLLAPI application and a PC-DOS SRPI requester
was not possible.  It was necessary for the PC-DOS user to manipulate
the 3270 terminal emulation connection and the CMS host by hand to
set up the proper host environment before starting the desired PC-DOS
program.  This invention removes the need for this manual
intervention, synchronizing SRPI and HLLAPI requests and setting up
the proper host environment automatically in response to PC-DOS
program needs.

      This invention consists of a software component called the
Arbiter.  The Arbiter governs the use of the CMS host. It keeps track
of whether a SRPI requestor or a HLLAPI program is using the host and
grants host access based on current host usage.  Having only one
access point to the host eliminates collisions between SRPI usage and
HLLAPI usage (see Fig. 1).

      The Arbiter tracks the following events in order to know the
current state of host usage:
o    The issuance of a SRPI request;
o    The completion of a SRPI request;
o    The start of a related group of HLLAPI calls;
o    The completion of a related group of HLLAPI calls.

      The Arbiter tracks the SRPI events automatically by monitoring
software interrupt 07Fh -- the entry point for SRPI requests.  It
requires the HLLAPI program, though, to signal the start and end of a
related group of HLLAPI calls by issuing two special Arbiter function
calls.  These function calls (PH-START and PH-END) define a unit of
HLLAPI work that should not be interrupted by SRPI usage.  These
function calls are necessary because individual HLLA...