sorry if my question in trivial but I'm wondering if it's possible to programmatically interact with an applet, reading the output it provides (a sort of web-scraping).
Assuming a certain website expose an applet, would it be possible to extract content from it through POST/GET requests (or other similar means) in a programming language like Java. My interaction is "black box like" as I have no access to the server environment.
Not sure what you mean. An applet is a Swing application running in the context of a browser and when you "hit" a URL for an applet the browser actually downloads the corresponding jar.
But there are ways to "manipulate" the applet and e.g. press a button or get a value programmatically and that is what automated UI suites do. I don't know how they do it though to be honest.Seems like a decompile and analysis on the fly