There is a server on one running java, how to expect a request on the other?

Question

linux

Let's say there are several dedicated servers (vps\vds\cloud doesn't matter), one of them has a web application.
The task of a web application is to accept a user's request on the site and give instructions to other servers.
Actually the question is: how to make a dedicated server wait for a request to it and when a request comes in, it executes a certain shell script. Can it somehow accept http request or web sockets?

Answer 1

And what about Java?
> a dedicated server was waiting for a request to it, and when the request comes in, it was executing a certain shell script
inetd, no?

Answer 2

RPC (Java RMI) should help you here.
Or dig deeper and fence the service.