PHP- Ajax and Redirect

If I understand what you want to happen then this is how I'm implementing it. It's in Prototype instead of jQuery but it shouldn't take you long to translate:

new Ajax.Request('process.php', {
    on401: function(response) {
        var redirect = response.getHeader('Location');
        document.location = redirect;
    }
});

In your PHP, output the following if the session is inactive:

header('Location: http://example.com/login.php', true, 401);
exit;

GWT (Google Web Toolkit) is probably the fastest way for a non-UI Java guy to build a complex, ajax-enabled, dynamic UI.

Thank you all for your inputs. I figured out a way to make it work.

I wanted to be able to send the data to the datatables within a jquery callback because this would allow me to create my own search outside the datatables. The way I've done it is by running an ajax call that performs the query to the database and then I pass the results of that query to the datatable but the issue was how to format the data in a way that the datatable would accept and how to make it read that data to display on the table.

Simple ajax call and populating the datatable

This code can be further modified (which I will do in my case) but it should give you an idea of how to accomplish what I've been wanting to do. (it works btw).

<script>
$('document').ready(function()
{
    $.ajax({
    type : 'POST',
    url  : 'test.php',
    dataType: 'json',
    cache: false,
    success :  function(result)
        {
            //pass data to datatable
            console.log(result); // just to see I'm getting the correct data.
            $('#test_table').DataTable({
                "searching": false, //this is disabled because I have a custom search.
                "aaData": [result], //here we get the array data from the ajax call.
                "aoColumns": [
                  { "sTitle": "ID" },
                  { "sTitle": "Name" },
                  { "sTitle": "Email" }
                ] //this isn't necessary unless you want modify the header
                  //names without changing it in your html code. 
                  //I find it useful tho' to setup the headers this way.
            });
        }
    });
});
</script>

test.php

This is the simple version I used for testing. My actual code is much more larger as it has several parts for querying and searching.

<?php

$columns = array( 
// datatable column index  => database column name
    0 => 'id',
    1 => 'name',
    2 => 'email',
);

$sql = "SELECT * FROM test_table";
$res = mysqli_query($conn, $sql) or die("Error: ".mysqli_error($conn));
$dataArray = array();
while( $row = mysqli_fetch_array($res) ) {


    $dataArray[] = $row["id"];
    $dataArray[] = $row["name"];
    $dataArray[] = $row["email"];

}

echo json_encode($dataArray);

?>

This simplifies things a lot, at least for me. I did not want to include additional libraries 'ssp.class.php'. I also did not want to get into PDO. So this has made it a lot more flexible and I hope it helps others who are trying to accomplish something similar.