How glassfish domains are separated from each other?

Question

GlassFish allows creating N domains. Every domain has its own Java classes (libraries etc) and system settings.

For example, we have two domains - domain1 and domain2.

Via GF web console (http://localhost:4848) one system property was set for domain1 - com.temp.foo=test1. Besides via GF web console (http://localhost:7575) one system property was set for domain2 - com.temp.foo=test2.

Now, in domain1

System.out.println(System.getProperty("org.temp.foo"))
//returns `test1`

And in domain2

System.out.println(System.getProperty("org.temp.foo"))
//returns `test2`

As I understand GF and all its domains are running in one instance of JVM. And I don't understand how it is possible in one instance of JVM separate system properties. Could anyone explain?

Note: I understand that it can be a very long explanation that's why I am asking only about main principle and solutions/libraries names in an order I could read about them on the internet.

Answer 1

It seems that the understanding "GF and all its domains are running in one instance of JVM" is wrong.

As per GlassFish current version's documentation (chapter 3):

A domain contains a group of GlassFish Server instances that are administered together. [...] A GlassFish Server instance is a single Virtual Machine for the Java platform (Java Virtual Machine or JVM machine) on a single node in which GlassFish Server is running.

That means, every single instance of any domain is running in its own JVM! As a consequence, they all could have their own different system properties.

To be fair: There are means for administering virtual servers in GlassFish, that seem to share a JVM, but I think you are not speaking about them.