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 trying 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
                {
                var oHttp = new ActiveXObject(versions[i]);
                return oHttp;
                }
                catch (error)
                {
                //do nothing here
                }
            }
        }
    return null;
}
HttpRequest.prototype.send = function ()
{
    this.request.send(null);
}