Mendix does allow this. It runs on JVM containers so from their own "action blocks" you can just say "Call Java action" and execute your code there. There is a

Mendix does allow this. It runs on JVM containers so from their own "action blocks" you can just say "Call Java action" and execute your code there. There is a java api that you can access from there. Pretty neat and that's how most plugins are built. On the client side you can do something similar with javascript.