NET/MASTER RMS Management and Operations Guide

2 Message Handlers, Timers,
Rulesets, and Rules
115415 NonStop NET/MASTER RMS Management and Operations Guide 2–1
This section describes the RMS message handlers, timers, rulesets, rules, and other
major elements of RMS. The following sections provide information on how to work
with the RMS elements described here:
For information on starting and controlling message handlers and timers, see
Section 9, “Controlling Message Handlers and Timers.”
For information on creating and developing rulesets and rules, see Section 5,
“Creating and Developing Rulesets and Rules,” and Section 6, “Updating and
Maintaining Rulesets, Rules, and Command Groups.”
Message Handlers The RMS message handler is an executing NCL procedure that processes messages
and takes actions according to a set of rules. You start the message handler with an
RMS ruleset. You can start the message handler as one of the following types:
EMS—An EMS-type message handler acts as the EMSPROC system-level NCL
procedure and processes external messages that come to NonStop NET/MASTER
MS. An EMS-type message handler uses the NCL verb EMSREAD to retrieve
messages. There can only be one EMS-type message handler in a NonStop
NET/MASTER MS system.
LOG—A LOG-type message handler acts as the LOGPROC system-level NCL
procedure and processes messages destined for the NonStop NET/MASTER MS
activity log. A LOG-type message handler uses the NCL verb LOGREAD to
retrieve messages. There can only be one LOG-type message handler in a
NonStop NET/MASTER MS system.
MSG—A MSG-type message handler acts as a MSGPROC system-level NCL
procedure and processes messages destined for an OCS window. A MSG-type
message handler uses the NCL verb MSGREAD to retrieve messages. There can
be only one MSG-type message handler for each OCS window.
INT—An INT-type message handler processes messages that arrive at its own
dependent queues. An INT-type message handler uses the NCL verb INTREAD
to retrieve messages. There can be more than one INT-type message handler in an
environment. You use INT-type message handlers to share the message
processing load in an environment and to target the message flow from specific
subsystems. Instead of using a single message handler to process the messages in
an environment, you use several INT-type message handlers to process the
messages—each processing a specific type of message.
Continuity of Message
Handler Operation
The EMSPROC message handler executes under the Event Management Service
Process (EMSP). If EMSP fails, it is recreated and EMSPROC restarts. Messages
received from slightly before the failure are resent to EMSPROC, to ensure that
EMSPROC misses no messages (though some messages will be reprocessed).
Therefore, you must cater for the case of EMSPROC, when restarted, receiving some
duplicate messages.
The LOGPROC message handler executes under the Activity Log Process (LOGP). If
LOGP fails, it is recreated, and LOGPROC restarts but might miss some messages.