I've tested with a simple telnet client installed inside the container, and it works well.

activate Foreground in Production, and in the terminal, use the command

telnet localhost 63300

I working on macOS, and with docker. When I activate foreground, browser tries to execute telnet with this port. Did you try to expose port to the same one on the host, 63300:63300?

When you have ISFS configured to multiple namespaces, you can just use copy-paste ability to copy files between isfs folder, or with using real folder.

https://github.com/intersystems-community/iris-driver-distribution

Still the same, only offline mode will save it only locally and will not save on server.

Why you don't want to update the server?

Yeah, this is why you need to store files locally. And it's right.

But does not say why you need to work offline, how do you check if your code is working as expected?

So, it will be like offline mode, not just local mode. In this case, you may just deactivate the connection, with "objectscript.conn.active": false.

But, many features, which require an active connection to the server will not be available as well.

Just curious, what are the reasons to work this way?

Link to documentation

Local way, is actually how it was designed by default, and how you'll get the best experience.

What issues did you face? 

In short how to start using it.

• You need to configure access to your server through parameters under "objectscript.conn"
• Use your local code, if you already have it, or export code from the server, once you are connected
• Edit and save files as a usual file, will save it on the server and compile it, in case of any compilation issues it will notify you about it.

You have to look at grade documentation. And it will be something like this. it says, to look at libs folder for jar files, usually it only uses some remote repositories like maven central

repositories {
    flatDir {
        dirs 'libs'
    }
}

btw, if you would need to call other method which is also Python

Class User.Test
{

ClassMethod SomeMethod() As %String
{
  quit "test objectscript"
}

ClassMethod SomePythonMethod() As %String [ Language = python ]
{
  return "test python"
}

ClassMethod PTest() [ Language = python ]
{
  import iris
  print(iris.cls(__name__).SomeMethod())
  print(Test.SomePythonMethod())
}

}

In this case this method appears can be accessible through the python class named as the current class (without package), in my case it's Test

This version is just outdated, InterSystems deletes old version, when they publish something newer. Use docker-ls tool, this will help to find all available versions 

Do not use %ZEN, it’s deprecated. There is Native JSON support, and %JSON.Adaptor, use this instead. Any output with write command will produce this error. 

I don't use Windows, but can say how it supposed to be

VSCode supports PowerShell terminal or cmd.exe, in case if you use wsl2, it can bee configured to open it as well.

But, there is a way, to open the terminal just in cmd.exe or from PowerShell, first you have to figure it out how to get it from there. iris.exe should have options, to run it inside the current terminal, I don't know if Windows version already has irissession, you could try it.

Do you use Windows, macOS or linux?