GDSX (Extended General Device Support) Manual

Extended General Device Support (GDSX) Manual—529931-001

4-1

DEVICE^HANDLER Example,

Running and Managing

The typical purpose of a DEVICE^HANDLER is to modify the communication of each

thread between a requester and another file. The GDSX program demonstrated in this

section, called the DEVICE^HANDLER example, includes a DEVICE^HANDLER

procedure that modifies communication between multiple requesters and the terminals

to which they are mapped. Figure 4-1 shows an overview of the processing done in

this unconverted example program. $A1 and $A2 are requester processes, each of

which communicates with a terminal by way of $GDS; the DEVICE^HANDLER in

$GDS does datastream conversion on messages sent from requester to terminal.

This section of the tutorial requires three terminals, designated the TACL terminal, the

first application terminal, and the second application terminal. (If a second application

terminal is not available, you can still do most of this section’s tutorial.) It is assumed

that the terminals are accessed by means of the TERMPROCESS IOP.

Figure 4-1. Overview of DEVICE^HANDLER Example

$A1

$GDS

Datastream

Conversion

Passthrough

Datastream

Conversion

Passthrough

$TC1

$TC2

D^H Task

VST012.vsd

$A1