function doRequest(method,url,async,onLoad,onProgress) {
    var xhr;
    if ((onProgress || isXDomainUrl(url)) && window.XDomainRequest) {
        // if it is x-domain or streaming/incremental updates are needed we will use IE's XDomainRequest for IE
        // streaming/interactive mode is broken in IE's XHR, but for some reason works in XDR (with onprogress), so we will
        // need to use XDR if incremental updates are necessary
        // see bug https://connect.microsoft.com/IE/feedback/ViewFeedback.aspx?FeedbackID=334813
         if (url.match(/^https:/) && !onProgress) {
            // XDR doesn’t work for secure https communication
            // see bug https://connect.microsoft.com/IE/feedback/ViewFeedback.aspx?FeedbackID=333380
            loadUsingScriptTag(url); // script tag insertion can be more secure than XDR
                                // in some situations because it supports https
            return;
        }
        xhr = new XDomainRequest;
        // relative paths don’t work in XDomainRequest, see bug https://connect.microsoft.com/IE/feedback/ViewFeedback.aspx?FeedbackID=333275
        if (!url.match(/^http:/)) { // test to see if it is an absolute url
            url = absoluteUrl(location.href,url); // must have a function to turn it into an absolute url
        }
        if (!(method == “GET” || method == “POST”)) {
            // XDomainRequest does not support methods besides GET and POST
            // see bug https://connect.microsoft.com/IE/feedback/ViewFeedback.aspx?FeedbackID=334809
            // We will try to add the method as a parameter and hope the server will understand… good luck :/
            url += “&method=” + method;
            method = “POST”;
        }
        function xdrLoad() {
           if (xhr.contentType.match(/\/xml/)){
                // there is no responseXML in XDomainRequest, so we have to create it manually
                var dom = new ActiveXObject(”Microsoft.XMLDOM”);
                dom.async = false;
                dom.loadXML(xhr.responseText,200);
                onLoad(dom);
           }
           else {
                onLoad(xhr.responseText,200); // we will assume that the status code is 200, XDomainRequest rejects all other successful status codes
                // see bug https://connect.microsoft.com/IE/feedback/ViewFeedback.aspx?FeedbackID=334804
           }
        }
        if (async === false) {
            // XDomainRequest does not support synchronous requests
            // see bug https://connect.microsoft.com/IE/feedback/ViewFeedback.aspx?FeedbackID=336031
            // so we will try to block execution on our own (which is not really possible in any reasonable manner)
            var loaded;
            xhr.onload = function() {
                loaded = true;
                xdrLoad();
            }
            xhr.open(method,url);
            xhr.send(null);
            while(!loaded) { // try to block until the response is received
                // I am sure the user won’t mind just clicking OK so we can block execution
                alert(”Waiting for the response, please click OK because it probably is here now”);
            }
            return;
        }
        else {  // do an asynchronous request with XDomainRequest
            xhr.onload = xdrLoad;
            xhr.open(method,url);
            xhr.onprogress = onProgress;
        }
    }
    // we will mercifully skip all the branches for ActiveXObject(”Microsoft.XMLHTTP”) to accomodate IE6 and lower
    else {
        xhr = new XMLHttpRequest; // use the standard XHR for same origin and browsers that implement cross-site
                        // W3C requests and streaming
        xhr.open(method,url,async);
        xhr.onreadystatechange = function() {
            if (xhr.readyState == 3) // interactive mode
                onProgress(xhr.responseText);
            if (xhr.readyState == 4) // finished
                onLoad(xhr.responseText,xhr.status);
        }
    }
    xhr.send(null); // finally send the request whether it be XDR or XHR
        // and supporting functions
        function absoluteUrl : function(baseUrl, relativeUrl) {
                // This takes a base url and a relative url and resolves the target url.
                // For example:
                // resolveUrl(”http://www.domain.com/path1/path2″,”../path3″) ->”http://www.domain.com/path1/path3″
                //
                if (relativeUrl.match(/\w+:\/\//))
                        return relativeUrl;
                if (relativeUrl.charAt(0)==’/') {
                        baseUrl = baseUrl.match(/.*\/\/[^\/]+/)
                        return (baseUrl ? baseUrl[0] : ”) + relativeUrl;
                }
                        //TODO: handle protocol relative urls:  ://www.domain.com
                baseUrl = baseUrl.substring(0,baseUrl.length - baseUrl.match(/[^\/]*$/)[0].length);// clean off the trailing path
                if (relativeUrl == ‘.’)
                        return baseUrl;
                while (relativeUrl.substring(0,3) == ‘../’) {
                        baseUrl = baseUrl.substring(0,baseUrl.length - baseUrl.match(/[^\/]*\/$/)[0].length);
                        relativeUrl = relativeUrl.substring(3);
                }
                return baseUrl + relativeUrl;
        }
        function loadUsingScriptTag(url) {
                … do JSONP here if we want
        }
}