This document discusses Apple Enterprise Technical Support's most commonly asked technical questions about WebObjects 4 and the WebObjects Monitor utility. For general deployment questions, see the WebObjects 4 Deployment FAQ, TIL article 70001 .

Please be aware that Monitor works very differently in WebObjects 4.5 than it does in WebObjects 4. Most of this information no longer applies to WebObjects 4.5. For more information on using Monitor with WebObjects 4.5, please see the WOInfoCenter on your local WebObjects 4.5 system.

Q: How do Monitor and MonitorProxy communicate?

A: As of WebObjects 4, Monitor and MonitorProxy communicate via Apple's Distributed Objects (DO) protocol.

Q: If I want to make Monitor talk to a MonitorProxy through a firewall, what ports should I open up?

A: You'll need to open up the following ports:

A: Use -WOPort <port_number> as the argument to any WO Application. As long as that port is currently available, the application will launch and will register to the given port. If the port you specify is already in use, the application will exit with a "Could not register with nameserver" error.

Q: Who holds on to the scheduling information for WebObjects applications--Monitor or MonitorProxy?

A: Monitor. Monitor talks directly to the applications. MonitorProxy is not involved in scheduling at all. In addition the applications do not hold onto any scheduling information. If Monitor dies, your scheduling will die until Monitor is back up.

The scheduling information is stored in the Monitor.conf file, located in NEXT_ROOT/Apple/Library/WebObjects/Configuration.

Q: Why do I have instances running that the Monitor can't communicate with?

A: This may happen when you are using the "Start auto recovery application when Monitor starts" setting. If your application takes more than thirty seconds to start up, the WebObjects auto-recover feature will time out and WebObjects will try to start a second instance. The second instance will fail because the first instance is using the port; there will now be a WebObjects application running with no connection to the Monitor. Make sure that your applications start in less than thirty seconds if you want to use this procedure (this should not be a problem for most WebObjects applications.)

Q: Why doesn't Monitor notice when my applications die?

A: WebObjects 4 uses DO to determine when an application has died. If the application server and the Monitor host are on different subnets, the DO message (a broadcast message) will not be received by the Monitor system. As a result, stopped applications will appear still to be running.

Q: How do I run MonitorProxy (or Monitor) to make sure that if it dies, it'll respawn?

A: Use MonitorDaemon. Depending on which application you specify, MonitorDaemon will execute and keep up either Monitor or MonitorProxy. Usage is fairly straightforward:

MonitorDaemon Monitor

or

MonitorDaemon MonitorProxy

In NT, you will want to first install MonitorProxy as a service and then configure it to start automatically. To install MonitorProxy or Monitor as a service, type "MonitorDaemon.exe -InstallMonitorProxy" or "MonitorDaemon.exe -InstallMonitor". Then go to the Services panel within the Control Panel and select the MonitorProxy or Monitor service. Set that service to start on boot up.

In UNIX, Monitor/MonitorProxy's startup should be in a start up script. Here is an example script for Solaris that starts Monitor on port 3000:

#!/sbin/sh
#
#       MonitorDaemon (Monitor) Startup Script
#       Damien Weiss
#       Apple Computer
#       March 1, 1999
#
#ident  "@(#)womonitor  1.0     99/03/01 DAW"

# The FILE variable is just the path to the executable.  MONITOR is the
# actual command line that is executed.

FILE="/opt/Apple/Library/WebObjects/Applications/Monitor.woa/MonitorDaemon"

MONITOR="/opt/Apple/Library/WebObjects/Applications/Monitor.woa/MonitorDaemon /opt/Apple/Library/WebObjects/Applications/Monitor.woa/Monitor -WOPort 3000"

case "$1" in
'start')
if [ -f ${FILE} ]; then
${MONITOR} >/dev/null 2>&1 &
fi

;;

'stop')
pid_daemon=`/usr/bin/ps -eo pid,comm | /usr/bin/awk '{ if ($2 =="/opt/Ap
ple/Library/WebObjects/Applications/Monitor.woa/MonitorDaemon") print $1 }'`
pid_monitor=`/usr/bin/ps -eo pid,comm | /usr/bin/awk '{ if ($2 =="/opt/A
pple/Library/WebObjects/Applications/Monitor.woa/Monitor") print $1}'`
if test "$pid_daemon"
then
/usr/bin/kill $pid_daemon
/usr/bin/kill $pid_monitor
fi

;;

*)
echo "Usage: $0 { start | stop }"
exit 1
;;
esac
exit 0