When one of these conditions, no response or a late response, is detected, the pro­
grammable operator facility invokes one of two EXECs supplied by IBM for this
purpose. For checking a distributed system, the PROPPCHK EXEC is invoked.
For checking of the host, the PROPHCHK EXEC is invoked.
The programmable operator doing the checking invokes the EXEC. For example,
if a programmable operator on a distributed system has a HOSTCHK statement in
its routing table, the PROPHCHK EXEC would be invoked if communication with
the host system were lost for a long enough period that the request or the response
were prevented from getting through. Similarly, if a programmable operator on a
host system has a PROPCHK statement in its routing table, that programmable
operator would invoke the PROPPCHK EXEC if communication with one of the
specified distributed nodes were lost for such a period. These EXECs are supplied
as samples only and may be modified or replaced with user-written EXECs, allow­
ing the user to tailor the resulting action(s).
The IBM-supplied PROPHCHK EXEC operates as follows:
When the logical operator's node fails to respond or resumes responding, type
a message on the programmable operator console and send a message to the
userid MAINT indicating that communication with the host system has been
broken or restored.
The IBM-supplied PROPPCHK EXEC operates as follows:
For each node that has failed to respond, notify the logical operator that the
programmable operator facility is unable to communicate with that particular
node (distributed system).
For each node that has resumed responding from a failed state, notify the log­
ical operator that communication with that node (distributed system) has been
reestablished.
How the Programmable Operator Establishes Communications with IV CV
The programmable operator facility automatically establishes communications with CP through the Inter-User Communications Vehicle (lUCV). When the program­
mable operator facility is initialized, a CMSIUCV CONNECT, specifying *MSG and an application id of PROP, is issued to establish the communications path with
the Message System Service (See the "Message System Service" section earlier in
this manual). This allows the programmable operator program to read and evaluate
messages directly from CPo Several CP command settings determine the types of messages that the program­
mable operator facility can receive. The programmable operator facility issues
these SET commands when initializing, and resets them when terminating. The
commands issued during initialization are: SET MSG IUCV SET WNG IUCV SET SMSG IUCV SET EMSG IUCV SET IMSG IUCV SET CPCONIO IUCV SET VMCONIO OFF The Programmable Operator Facility 449

Message Output Format VMCONIO is set OFF so that any messages produced by CMS or the programma­
ble operator during initialization of the programmable operator facility are typed on
its virtual machine console. If VMCONIO was set to IUCV, such data would be
trapped by IUCV and not displayed.
When the programmable operator STOP command is issued, the following SET commands are issued: SET MSG ON SET WNG ON SET SMSG OFF SET EMSG ON SET IMSG ON SET CPCONIO OFF SET VMCONIO OFF Then, after the existing messages are handled, the IUCV connection is severed
using the IUCV SEVER function. Some other virtual machine settings that the programmable operator facility modi­
fies are "SET RUN ON", "SET TIMER REAL", and "TERMINAL MODE VM" at initialization, and "SET RUN OFF" and "SET TIMER ON" at termination. "SET RUN ON" is issued to ensure that the programmable operator is not held up
in CP console function mode for excessive periods of time, either because of some
operator command entry or because of logging on to a disconnected programmable
operator virtual machine. "TERMINAL MODE VM" is to ensure that program­
mable operator console commands are handled correctly.
Note: SCIF (Single Console Image Facility) operation supersedes IUCV Message System Service operation. If the programmable operator virtual machine has a SCIF secondary user, messages would be sent via SCIF to the secondary user rath­
er than handled by the programmable operator virtual machine through the IUCV Message System Service. However, the programmable operator facility may be a SCIF secondary user for another virtual machine. For example, this can be used to
control the operation of a guest operating system running in another virtual
machine. In this case, SCIF messages is presented to the programmable operator
virtual machine as IUCV message-type 8.
The messages and responses from the programmable operator facility are sent via
the CP MSGNOH command if the programmable operator virtual machine has user
class B authorization. Otherwise, the CP MESSAGE command is used. Regard­
less of which message command is used the messages from another user that are
routed to the logical operator are prefixed with the userid and nodeid of the origi­
nating user.
The format of these messages appears as follows:
col 1 I v
userid
col 10 I V
nodeid:
col 20 I v
text
Messages that the programmable operator facility sends as responses to the issuer
of a programmable operator command Of an asynchronous message to the CP operator originating at the programmable operator virtual machine have no such
prefix. 450 VM/SP System Programmer's Guide