Getting the screen resolution using PHP

You can't do it with pure PHP. You must do it with JavaScript. There are several articles written on how to do this.

Essentially, you can set a cookie or you can even do some Ajax to send the info to a PHP script. If you use jQuery, you can do it something like this:

jquery:

$(function() {
    $.post('some_script.php', { width: screen.width, height:screen.height }, function(json) {
        if(json.outcome == 'success') {
            // do something with the knowledge possibly?
        } else {
            alert('Unable to let PHP know what the screen resolution is!');
        }
    },'json');
});

PHP (some_script.php)

<?php
// For instance, you can do something like this:
if(isset($_POST['width']) && isset($_POST['height'])) {
    $_SESSION['screen_width'] = $_POST['width'];
    $_SESSION['screen_height'] = $_POST['height'];
    echo json_encode(array('outcome'=>'success'));
} else {
    echo json_encode(array('outcome'=>'error','error'=>"Couldn't save dimension info"));
}
?>

All that is really basic but it should get you somewhere. Normally screen resolution is not what you really want though. You may be more interested in the size of the actual browser's view port since that is actually where the page is rendered...

I would NOT use raw sockets to do this. Instead use JSON over HTTP because PHP supports processing HTTP without any special consideration. It's simple to run your PHP pages on the hosted apache instance on GoDaddy or Amazon EC2. Sure you can use sockets, but very very few people actually do that. Massively more people process and respond to HTTP with PHP. That means you'll find vastly more people who can help answer your questions if you follow the herd here. Also there are API libraries on both sides for doing this easily. Using sockets comes with plenty of things you'll have to do yourself or suffer through all the strange bugs that comes with working with raw sockets for the first time.

Also JSON processing is easily supported by both Java and PHP to it's very easy to send the data to the client and server using that.

Well you can certainly use PHP on the backend and Java on the frontend if you like, but I'd suggest canceling your Go-Daddy account and get an Amazon EC2/S3 account because you get a full machine dedicated to whatever you want to put on it. So if you want to do Java on the backend you can just by installing the JDK, Tomcat, etc yourself on the amazon instance and you're good to go. You can also host PHP on there too. There is even plenty of AMI instances pre-installed for Java or PHP stacks.

No, AFAIK this is not possible.