How come the client side clicking can't cause a function in web server side being called?

[Stan Huang]

Below are my AJAX code snippet.
In rescanNetwork(), there are two calls of newAJAXCommand(). The first one “newAJAXCommand(‘scan.cgi?scan=1’);” The second one is “setTimeout(“newAJAXCommand(‘status.xml’, updateStatus, false)”, 50)”
The content of scan.cgi is kind of “Success! scan”. My questions are:

1. Per my understanding, scan.cgi must be a CGI script written in Perl, Python, or another scripting language. “Success! scan” doesn’t look like a script of any language. How come? What does it mean?
2. What is this call “newAJAXCommand(‘status.xml’, updateStatus, false)” for? where ‘updateStatus’ is a JavaScript function as below.
3. In “newAJAXCommand”, once “newAjax.ajaxReq.send(data);” is executed, the server side associated function must be called, but I found no function was called. How can I find the missing place?

// Initiates a new AJAX command
//  url: the url to access
//  container: the document ID to fill, or a function to call with response XML (optional)
//  repeat: true to repeat this call indefinitely (optional)
//  data: an URL encoded string to be submitted as POST data (optional)
function newAJAXCommand(url, container, repeat, data)
{
    // Set up our object
    var newAjax = new Object();
    var theTimer = new Date();
    newAjax.url = url;
    newAjax.container = container;
    newAjax.repeat = repeat;
    newAjax.ajaxReq = null;

    // Create and send the request
    if (window.XMLHttpRequest) {
        newAjax.ajaxReq = new XMLHttpRequest();
        newAjax.ajaxReq.open((data==null)?"GET":"POST", newAjax.url, true);
        newAjax.ajaxReq.send(data);
    // If we're using IE6 style (maybe 5.5 compatible too)
    } else if (window.ActiveXObject) {
        newAjax.ajaxReq = new ActiveXObject("Microsoft.XMLHTTP");
        if (newAjax.ajaxReq) {
            newAjax.ajaxReq.open((data==null)?"GET":"POST", newAjax.url, true);
            newAjax.ajaxReq.send(data);
        }
    }

    newAjax.lastCalled = theTimer.getTime();

    // Store in our array
    ajaxList.push(newAjax);
}

.......
function updateStatus(xmlData)
{
    ......
}
.....

function rescanNetwork()
{
    scanDots = 0;
    printButtonName();
    document.getElementById("rescan").disabled = true;

    // Generate a request to hardware to issue a rescan
    newAJAXCommand('scan.cgi?scan=1');

    // Delete old table, replace with new table after scan is finished
    deleteScanTable();

    currBss = 0; // Reset the current bss pointer

    setTimeout("newAJAXCommand('status.xml', updateStatus, false)", 50);
}