GDSX (Extended General Device Support) Manual

Extended General Device Support (GDSX) Manual—529931-001
6-1
6
LINE^HANDLER Example, Running
and Managing
The typical purpose of a DEVICE^HANDLER task is to modify the communication of
each thread between a requester and another file. The typical purpose of a
LINE^HANDLER is to allow each thread to use a shared resource without allowing the
threads to interfere with each other.
The GDSX program demonstrated in this section includes a LINE^HANDLER
procedure that manages communication of multiple requester processes with the same
resource, a terminal. (Section 4, DEVICE^HANDLER Example, Running and
Managing and Section 5, DEVICE^HANDLER Example, Design use the same program
but do not call the LINE^HANDLER procedure.) Figure 6-1 shows the environment for
this example.
$A1, $A2, and $A3 are requester processes, each of which communicates
simultaneously with the same file (a terminal) by way of GDSX. T1, T2, and T3 are
DEVICE^HANDLER tasks, and LX is a LINE^HANDLER task.
Figure 6-1. Environment of the LINE^HANDLER Example
$A1
$A2
$A3
T1
T2
T3
LX
$GDS
D^H
L^H
D^H
IOCB
Queue
$TC1
VST022.vsd