textray VS tn5250j

This is really interesting and I see a lot of parallels (e.g. screen abstraction, etc.) between this and my own terminal emulation library (https://github.com/KazDragon/terminalpp, see https://github.com/KazDragon/textray for a fully-fledged example). We should collab some time.

Your users are probably using some of the extended functionality from IBM's client, but keep in your back pocket that third party tn5250 clients will also work. An example that supports TLS (telnet over TLS, or telnets) is tn5250j, which runs in a JVM.

Video author here -- The terminal emulator is tn5250j [0], configured to use the IBM Plex Mono [1] font. Full-screen it on a 1080p display and it really is quite pleasant! And there's something that just feels "right" about using IBM's font in this case.

[0] http://tn5250j.org/

There's also telnets://, telnet over TLS on tcp/992. That's rare to find outside of tn5250 and tn3270 host terminal emulations, but we use it here and there. The tn5250j open-source client supports telnets, and you should be using telnets if you're using tn5250.

But there are also third party solutions, like this Java-based tn5250 client that supports TLS encryption for sessions. It often seems like mainstream users need nothing that can't be solved with third-party software. Perhaps developers might need some feature in Client Access, but not app users, generally.

There are various reasons why sites might want to use the official IBM Client Access app (Java) on an MS TS, but at the same time mainstream users aren't usually using those features. Depending on the site, users can use a generic tn5250 client with TLS encryption support (also Java).

If the AS/400 application is just a tn5250 client, then you can use anything that supports tn5250+TLS, like this Java based one that runs fine on OpenJDK. If it's a currently-supported version of IBM ACS, then ask IBM -- they used to have their own JDK/JRE.