function HttpRequest(sUrl, fpCallback) 
{
    this.request = this.createXmlHttpRequest();
    this.request.open("GET", sUrl, true);

    var tempRequest = this.request;
    function request_readystatechange() 
    {
        if (tempRequest.readyState == 4) 
        {
            if (tempRequest.status == 200) 
            {
                fpCallback(tempRequest.responseText);
            } 
            else 
            {
                alert("An error occurred while attempting to contact the server.");
            }
        }
    }
    
    this.request.onreadystatechange = request_readystatechange;
}

HttpRequest.prototype.createXmlHttpRequest = function () 
{
    if (window.XMLHttpRequest) 
    {

        var oHttp = new XMLHttpRequest();
        return oHttp;

    } 
    else if (window.ActiveXObject) 
    {

        var versions = 
        [
            "MSXML2.XmlHttp.6.0",
            "MSXML2.XmlHttp.3.0"
        ];

        for (var i = 0; i < versions.length; i++) 
        {
            try 
            {
                oHttp = new ActiveXObject(versions[i]);
                return oHttp;
            } 
            catch (error) 
            {
              //do nothing here
            }
        }

    }

    return null;
}

HttpRequest.prototype.send = function () 
{
    this.request.send(null);
}