GDSX Manual

Operations and Support
Extended General Device Support (GDSX) Manual–134303
3-4
Running SCF and Starting Requesters
Running SCF and Starting Requesters
A GDSX application is usually designed either to never run with a LINE or to always
run with one or more LINEs. (The tutorial example programs are unusual, because they
can be run either without any LINE or with one or more LINEs.) In any case, SCF is
normally used to configure the GDSX application. The two basic configurations are:
•
Without a LINE
This type of configuration requires that the devices have unique Guardian file names
that can be opened directly by GDSX. Some access methods that support this kind
of direct access are AM3270, Async Termprocess, X25AM, and CSS Async (6100).
In this type of configuration there can be dynamic SUs and preconfigured SUs. A
dynamic SU is an SU not configured through SCF, but created when an external
process opens a file through GDSX. A preconfigured SU is an SU configured with
SCF before a requester sends GDSX an OPEN for the file associated with the SU.
•
With a LINE
These applications involve shared data communications facilities where the line (or
message switching process) has a Guardian file name, but the individual devices on
the line do not. Some data communications products that do not allow direct
addressing of terminals on lines are CP6100 ADCCP/NRM, CP6100 Bisync
Multipoint, Envoy, and EnvoyACP/XF.
In this type of configuration there can be (preconfigured) LINEs, dynamic SUs, and
preconfigured SUs.
Running GDSX Without a LINE
In all of the following examples of commands used to configure GDSX applications
without a LINE, the requester program APPLS is used. (A listing of APPLS appears in
Appendix A.)
The OUT file specified in the RUN command used to start APPL is used by APPL to
open GDSX. The OUT file always specifies the name of a GDSX process qualified by a
subdevice name. (GDSX requires that external processes provide a two-level or three-
level qualified name when opening GDSX. A simple process name, for example,
$GDSX, is not allowed.)
An example of how Pathway/TS requesters may be used in a GDSX application is
provided in “Running a Pathway/TS Application” on page 3-9.
The simplest GDSX configuration has no LINE and only dynamic SUs. Here are
commands for a configuration that does I/O by means of a device $TC1:
> RUN GDSE /NAME $GDSX, NOWAIT/
> RUN APPL /NAME $A1, OUT $GDSX.#TC1, NOWAIT/
The default for the configuration parameter MAXLINES (the maximum number of
LINE^HANDLER tasks) is 0, so this parameter value is not entered. (This is how the
GDSX example program is started in Section 4.)