GDSX (Extended General Device Support) Manual

Overview of GDSX
Extended General Device Support (GDSX) Manual—529931-001
1-14
Indirect Terminal Access
Using PATHCOM, you configure SUs that Pathway/iTS is to open through GDSX. For
example, if a Pathway/iTS requester is to communicate through a GDSX process
named $GDS with a subdevice DEV2 configured under line $LINE1, the file name
$GDS.#LINE1.DEV2 is used in the following PATHCOM commands:
= SET TERM TCP TCP-X
= SET TERM TYPE T16-6530:0
= SET TERM INITIAL LOGON-SCREEN
= SET TERM FILE $GDS.#LINE1.DEV2
= ADD TERM TX-2
A session or thread is established when you issue the PATHCOM command:
= START TERM TX-2
Then the TCP opens the file specified in the configuration commands,
$GDS.#LINE1.DEV2 in this example. Within the GDSX process, TSCODE receives
the open message, derives the name $LINE1.#DEV2 from the message, and
determines from configuration information previously entered with SCF that device
$DEV2 is configured under line $LINE1. TSCODE sets a flag to indicate that the SU is
open and notifies the LINE^HANDLER of the open.
The LINE^HANDLER must handle the protocol so that requests are properly routed to
the SU device under the line. Then GDSX creates a DEVICE^HANDLER task to
modify the communication of the thread, by datastream conversion, for example. The
thread established among requester, DEVICE^HANDLER task, LINE^HANDLER task,
line, and terminal is fixed for the life of the open.
Typical transaction flow in this environment can be outlined as follows and is shown in
Figure 1-8:
•
When a Pathway/iTS requester submits a request to GDSX, the request is picked
up by the DEVICE^HANDLER task associated with the requester.
•
The task processes the request, and passes it to TSCODE, which queues the
message up to the LINE^HANDLER task associated with this DEVICE^HANDLER
task.
•
At this point the LINE^HANDLER task may, for example, issue one I/O request to
the target device, or the task may issue one I/O request to each device attached to
the line (as would be the case in a multidrop environment).