Experimental Physics and
Industrial Control System

NICOLE Remi via Tech-talk <tech-talk at aps.anl.gov> · Mon, 13 May 2024 13:14:31 +0000

Hello all,

I've seen that the Archiver Appliance installation guide[1] creates a
setup where it starts 4 separate instances of Tomcat:

- an instance for the engine
- an instance for the retrieval
- an instance for the etl
- an instance for the mgmt

[1]:
https://urldefense.us/v3/__https://slacmshankar.github.io/epicsarchiver_docs/installguide.html__;!!G_uCfscf7eWS!Z2-GGCoxxH2RhA7sGMTUxoZOyXLRxjdk_VU9aaPMtJ3-yGULuO75DEzFXGGqqyZIxLwKV9GHm7sR6wDnWhTQXIRIZw$ 

While trying to integrate it into EPNix[2], I found that the NixOS
configuration system currently doesn't have support for creating
multiple Tomcat instances.

[2]: https://urldefense.us/v3/__https://epics-extensions.github.io/EPNix/__;!!G_uCfscf7eWS!Z2-GGCoxxH2RhA7sGMTUxoZOyXLRxjdk_VU9aaPMtJ3-yGULuO75DEzFXGGqqyZIxLwKV9GHm7sR6wDnWhRqeU-Bpw$ 

So I've tried to put the 4 .war files inside the same Tomcat instance,
and everything seems to be working quite well.

My question is: what was the reasoning behind starting multiple Tomcat
servers inside the same server? Does it have something to do with
reliability? Or for ease of migration?

By intuition, I kinda prefer having the one instance, because it has
less configuration to maintain, and shoudl consume less resources, but
I might be missing something.

Thanks in advance and have a great dat!
-- 
Rémi NICOLE <remi.nicole at cea.fr>
CEA/DRF/IRFU/DIS/LDISC

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System