Creating a Unix daemon or NT Service in 100% Java
Hello all,
had a hard time deciding where to post this question, but finally decided to do it here because it seems to relate to the lifecycle of the JVM.
I am writting a server (SocketServer-handler thread implementation) and right now it has all been a breeze, it starts, binds to its port, listens, creates sockets and threads to handle the communication and sits doing this in a loop forever until stop.
it's your regular server with the only difference that it runs on the foreground as user and not on the background as a daemon, like all good servers.
At first I thought making it a daemon thread would solve the problem, but it turns out daemon threads are only 'daemonic' relative to their amin thread and get killed when there are no more normal threads to service.
After doing some research I've found at least five different ways of doing this but all involve writting os dependent code in C, C++ or VC++, which has to horrible drawbacks: platform dependency (writting four or five implementation of a java program is an oximoron) and that I don't know C or C++ yet.
I can believe that Java has no way to preform this basic and very useful feature. Are all Java servers hybrids of Java and other languages?
Any help will be inmenselly appreciated, and credit given on the software and future article (which I will write to help any other lost souls trying to accomplish this seemingly impossible task, like me)
TIA
depeupleur
[1512 byte] By [
depeupleur] at [2007-9-26 5:44:04]
Hi jschell, thanks for your answer.
That's strange, I thought the JVM was precisely an abstraction to let Java be built on top of diverse OS. Is it too low level for the JVM to handle.
I'm also thinking of implementing it as a Servlet, if it can't be a daemon, it might be useful to use other daemons instead, like a web container.
Do you have any other suggestions.
Thanks in advance,
Here is a startup script (in /etc/rc.d/init.d/jchat on linux RH 7, and enabled with chkconfig)
##############################################
#!/bin/sh
#
# Startup script for the Java chat server
#
# chkconfig: 345 99 01
# description: Chat server (Java Application).
# processname: jchat
# pidfile: /usr/local/chat/jchat.pid
###### start editing here ######
# user to run the process as:
USER=chat
# start & stop scripts
START_SCRIPT=/usr/local/chat/start_jchat.sh
STOP_SCRIPT=/usr/local/chat/stop_jchat.sh
###### stop editing here ######
start(){
$START_SCRIPT
#su - $USER -c $START_SCRIPT
}
stop(){
$STOP_SCRIPT
#su - $USER -c $STOP_SCRIPT
}
# See how we were called.
case "$1" in
start)
start
;;
stop)
stop
;;
restart)
stop
sleep 3s
start
;;
*)
echo "Usage: $0 {start|stop|restart}"
exit 1
esac
exit 0
##############################################
Here is start_jchat.sh
##############################################
#!/bin/sh
# java location
JAVA=/usr/local/jdk/bin/java
# jar archive:
JARARCHIVE=/usr/local/chat/jchat/com.romandie.chat.jar
# postgresql driver
PGSQLDRIVER=/usr/local/pgsql/share/java/postgresql.jar
# pid file
PIDFILE=/usr/local/chat/jchat.pid
# common log file:
COMMON_LOG=/usr/local/chat/logs/jchat-common_log
#error log file:
ERROR_LOG=/usr/local/chat/logs/jchat-error_log
export CLASSPATH=$CLASSPATH:$PGSQLDRIVER:$JARARCHIVE
echo $CLASSPATH
echo -n "Starting: $JARARCHIVE"
$JAVA xx.xxxxxx.chat.Server 1>>$COMMON_LOG 2>> $ERROR_LOG &
echo $! > $PIDFILE
echo "OK"
##############################################
Here is stop_jchat.sh
##############################################
#!/bin/sh
# jar archive:
JARARCHIVE=/usr/local/chat/jchat/xxx.xxxxx.chat.jar
# pid file
PIDFILE=/usr/local/chat/jchat.pid
echo -n "Shutting down: $JARARCHIVE"
kill -9 `cat $PIDFILE`
echo "OK"
##############################################
hope this helps
-leo
