A quick Java program to check if a server is up or a service on a server is up.

Monitor.java

import java.net.InetAddress;
import java.net.Socket;

import java.io.IOException;
import java.net.UnknownHostException;

public class Monitor {
    
    public static void main(String[] args) {
        if(args.length < 2) {
            System.out.println("Bad number of arguments.");
            return;
        }

        String server = args[0];
        int port = Integer.valueOf(args[1]);

        try {
            InetAddress ina = InetAddress.getByName(server);

            if(ina.isReachable(3000)) {
                System.out.println("Server is up.");
            } else {
                System.out.println("Server is down!");
                return;
            }

        } catch (IOException ioe) {
            ioe.printStackTrace();
            return;
        }

        Socket socket = null;
        try {
            socket = new Socket(server, port);

            if(socket.isConnected()) {
                System.out.println("Service is up on port " + port + ".");
            } else {
                System.out.println("Service is down on port " + port + "!");
            }            
        } catch (IOException ioe) {
            ioe.printStackTrace();
        } finally {
            if(socket != null && socket.isConnected()) {
                try {
                    socket.close();
                } catch (IOException ioe) {
                    ioe.printStackTrace();
                }
            }
        }

        return;
    }
}

Not working

Not surprising, this is from seven years ago.