从PHP网站发送tcp请求到JAVA程序

Question

I want to send a TCP Request from my website to my java application. So my java application should be able to receive a JSON array and print it.

I searched around for a few hours, but I could not find a solution.

Here is, what I have in PHP:

<?php

$array = array(
  0 => "test",
  1 => "test1"
);

json_encode($array);

$host = "tcp://localhost";
$port = 8123;
$data = json_encode($array);
$errstr = '';
$errno = '';

if ( ($fp = fsockopen($host, $port, $errno, $errstr, 3) ) === FALSE)
    echo "$errstr ($errno)";
else {
    print 'SUCCESS!<br />';
    fwrite($fp, $data);
    while (! feof($fp)) {
        echo fgets($fp, 4096);
    }
    fclose($fp);
}

My Java code:

public class tcp {

            public static void main(String argv[]) throws Exception {
                String clientSentence;
                String capitalizedSentence;
                ServerSocket welcomeSocket = new ServerSocket(8123);

                while (true) {
                    Socket connectionSocket = welcomeSocket.accept();
                    BufferedReader inFromClient =
                            new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
                    DataOutputStream outToClient = new DataOutputStream(connectionSocket.getOutputStream());
                    clientSentence = inFromClient.readLine();
                    System.out.println("Received: " + clientSentence);
                    capitalizedSentence = clientSentence.toUpperCase() + '
';
                    outToClient.writeBytes(capitalizedSentence);
                    connectionSocket.close();
                }
            }

    }

So as you should see, I never have done something like this before. My questions:

1) Do I have to open port "8123", also when the website and my application will run on localhost (ubuntu / debian)? -> how should I open them correctly?

2) When I start my app, I think I have to create the "tcp" java object. -> tcp tcp = new tcp - is this enough or do I have to call a method other something similar?

3) What do I have to change in my code? The Application does just nothing when I send a request...

So I hope you guys can help me with my problem :) Greets

EDIT:

When I try to run my PHP script, I git following error:

Warning: fsockopen(): unable to connect to tcp://localhost:8123 (Connection refused) in /PATH_TO_PHP/TCPSEND/index.php on line 16
Connection refused (111)