How to start a independant Daemon program from another java daemon?

Question

Hello,
I made two java daemon program Daemon_A and Daemon_B. By definition these two program work whithout any user interaction but most of it they should never fall down.
So in order to be sure that the both daemon are up (and to prevent any failure) I create a mechanism to check each other and if one is down it will be restart by the other one.
Up to now I succeed to restart the one who fall down. But ... there is always a but ...
At start:
- 1) Daemon_A and Daemon_B start.
- 2) Daemon_B fall down.
- 3) Daemon_A restart Daemon_B using this:
   String[] commandArray = new String[3];
   commandArray[0] = "../bin/java";
   commandArray[1] = "-jar";
   commandArray[2] = "Daemon_B.jar";
   Process oProcess = runtime.exec ( commandArray, (String[]) null);- 4) Daemon_A and Daemon_B are UP again.
- 5) Daemon_A crash then Daemon_B is kill too.
So once the Daemon_B is restarted it seems that there is still a link between Daemon_A and Daemon_B.
As I use a command system to restart the daemon I don't understand why my Daemon_B is dependant from the Daemon_A.
Is there another way of doing this?
How can I restart my Daemon_B (from the Daemon_A) in a independant process?
As i'm running out of idea any help will be apreciate,
thanks
Emmanuel

Answer 1

Because you do not need javaw on Unix. You can achieve
what you want in the normal Unix way. Confer: nohup,
&, stderr and stdout redircetion.That's not correct, I can not achieve what I want on Unix.
Well with the above piece of code if I use javaw for launching my command through a system command (runtime.exec) on windows it will start a 100% independant process which is find.
But under unix if I keep using simply java the process will stay a child process. Which mean if the "father daemon_A" die daemon_B will die too.
So that's why I woudering if there is a similar program as javaw on unix to avoid create chid process using 'runtime.exec'.
You mentioned crontab: it does not make an item to act
as a deamon, it rather periodically runs it. Yhea you right my mistake I don't use the crontab to launch the program. I use "etc/init.d" (for sun solaris) and service for windows. Otherwise the daemons are "real" daemon: one's they are started they keep listening and should never fall. But to get a hight level of security I want to be sure if one fall it will be restarted whithout beeing a child process of the other one.
so any idea on unix of how can I re-start a daemon in a independant way?
regards,
emmanuel