NET/MASTER Network Control Language (NCL) Programmer's Guide

Displaying a Panel
Working With Panels
14–60 106160 Tandem Computers Incorporated
If the current owner of the window is executing with CONTROL SHAREW in effect, it
automatically gives up its ownership to any other NCL process that executes a PANEL
verb. The previous owner is then logically stacked behind the new owner. When the
new owner ends or executes the PANELEND verb, the previous owner’s panel is
redisplayed.
The most common use of asynchronous NCL processes competing for a window is in
an OCS environment. A user may have several independent NCL processes executing
in the NCL processing environment associated with an OCS window. These NCL
processes might monitor the status of various items in the network and report to the
operator when an error condition occurs by issuing a PANEL verb to take over the
window.
The NCL processes would be written to use the CONTROL NOSHAREW option,
preventing any other NCL processes from “stealing” the window from them once they
had displayed their panel. On acknowledgement of their panel by the operator, the
NCL processes would then issue the PANELEND verb to release their ownership. The
window would then revert to the next waiting NCL process, or to OCS.
Note If a panel description file is defined using INWAIT=0, indicating that the issuing NCL process regains
control immediately after the panel is displayed, NonStop NET/MASTER MS guarantees to display the
panel before the issuing NCL process is allowed to continue. This may involve a wait for some other NCL
process to release control of the window.