How to setup Jmeter as server and send messages to Client over TCP

Question

Am trying to setup Jmeter as server and send messages from Jmeter to a client TCP connection.

But unfortunately, Options in TCP Sampler of Jmeter make it a client.

Answer 1

You can turn JMeter into a TCP Server by creating a ServerSocket inside the JSR223 Sampler using Groovy language.

Example code you can see i.e. in Java Program to Send a Message from Client to Server and Receive a Response Back Using Socket Programming article which provides an example of a TCP server which gets a number and returns it to the client multiplied by 2:

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class Server
{

    private static Socket socket;

    public static void main(String[] args)
    {
        try
        {

            int port = 25000;
            ServerSocket serverSocket = new ServerSocket(port);
            System.out.println("Server Started and listening to the port 25000");

            //Server is running always. This is done using this while(true) loop
            while(true)
            {
                //Reading the message from the client
                socket = serverSocket.accept();
                InputStream is = socket.getInputStream();
                InputStreamReader isr = new InputStreamReader(is);
                BufferedReader br = new BufferedReader(isr);
                String number = br.readLine();
                System.out.println("Message received from client is "+number);

                //Multiplying the number by 2 and forming the return message
                String returnMessage;
                try
                {
                    int numberInIntFormat = Integer.parseInt(number);
                    int returnValue = numberInIntFormat*2;
                    returnMessage = String.valueOf(returnValue) + "\n";
                }
                catch(NumberFormatException e)
                {
                    //Input was not a number. Sending proper message back to client.
                    returnMessage = "Please send a proper number\n";
                }

                //Sending the response back to the client.
                OutputStream os = socket.getOutputStream();
                OutputStreamWriter osw = new OutputStreamWriter(os);
                BufferedWriter bw = new BufferedWriter(osw);
                bw.write(returnMessage);
                System.out.println("Message sent to the client is "+returnMessage);
                bw.flush();
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            try
            {
                socket.close();
            }
            catch(Exception e){}
        }
    }
}