Processing

import processing.net.*;

int port = 10002;
Server myServer;

void setup()
{
  size(400, 400);
  background(0);
  myServer = new Server(this, port);
}

void draw()
{
  // Get the next available client
  Client thisClient = myServer.available();
  // If the client is not null, and says something, display what it said:
  if (thisClient !=null) {
    String whatClientSaid = thisClient.readString();
    // If the client says "exit", disconnect it
    if (whatClientSaid.equals("exit\r\n")) {
      thisClient.write("You will be disconnected now.\r\n");
      println(thisClient.ip() + "\t has been disconnected");
      myServer.disconnect(thisClient);
    } 
  } 
}