
Common Configuration
# P0602477 Ver: 3.1.11 Page 215
Interapplication/Host Service Daemon Data Exchange
VMST (VMS)
In a multi-MPS network environment, applications running on different nodes can
exchange data with each other via the local VMST (VENGINE Message Server -
Extended) service daemons. VMST is an ASE software process that performs
message server functions for VENGINE. It funnels VOS messages that have been
translated by VAMP to VENGINE processes and service daemons. VMST interprets
and supports all pre-existing VMS options, allowing scripts incorporating them to
continue functioning under the present release without any modifications. For
additional information, see VMST on page 36.
VMST is aliased as vms in its SRP startup and services files, but should not be
confused with previous (“non-extended”) versions of VMS.
In order for this functionality to be enabled, the connections between VMST daemons
on the various MPS systems must be established at the time of startup. This is done by
placing vms commands with appropriate options in either the ase.cfg or
gen.cfg files, as applicable (see Starting Under SRP on page 215). In addition,
appropriate port numbers for the VMST servers must be specified in the services
file (see The /etc/services File on page 129).
The following is important information about configuring inter-VMST
communication:
• In the configuration file(s), VMST-to-VMST connections are established
from one VMST to another. Although the specification is made one way, it is
a two-way communications channel, and the applications associated with any
VMST may send messages to any applications associated with the other.
• Connections are established between the VMST processes at startup.
However, when sending messages, applications must specify the destination
VMST number and application line number. As soon as a connection is
established, applications can send data to each other in both directions.
• To guarantee a correct connection, both VMSTs (connecting and accepting)
must be started with the -s option and be specified with different service
port numbers. If the accepting VMST is not available, the connecting VMST
will retry periodically, every 3 seconds, until the connection is established.
Starting Under SRP
Previously, VMS’ were only defined in the $MPSHOME/mpsN/etc/ase.cfg file.
Under ASE 4.7.1, VMST (running in place of VMS) may also be specified in the file
$MPSHOME/common/etc/gen.cfg. When used with a single MPS, VMST is
started by SRP through the ase.cfg file. When used with multiple MPS’ (whether
real or virtual), it is started through the
gen.cfg file.
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