I would recommend using glassfish. This way you only have on managment tool and configurations to master and maintain.
You have a couple different ways of running Glassfish here:
1. add different HTTP listeners/servers to your existing Glassfish domain
2. create a new glassfish domain using.
The second option allows you to use different VM's. This way you would not need 2 full glassfish installs.
We use multiple domains with a single install. It allows us to keep all of our servers (domains) up to date.
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