function Ajax() {
    this.req = null;
    this.url = null;
    this.method = 'GET';
    this.async = true;
    this.status = null;
    this.statusText = '';
    this.postData = null;
    this.readyState = null;
    this.responseText = null;
    this.responseXML = null;
    this.handleResp = null;
    this.responseFormat = 'text'; // 'text', 'xml', or 'object'
    this.mimeType = null;

    this.init = function() {
        if (!this.req) {
            try {
                this.req = new XMLHttpRequest();
            } catch (e) {
                try {
                    this.req = new ActiveXObject('MSXML2.XMLHTTP');
                } catch (e) {
                    try {
                        this.req = new ActiveXObject('Microsoft.XMLHTTP');
                    } catch (e) {
                        return false;
                    }
                }
            }
        }
        return this.req;
    };
    
    this.doReq = function() {
        if (!this.init()) {
            alert('Could not create XMLHttpRequest object.');
            return;
        }
        this.req.open(this.method, this.url, this.async);
        if (this.mimeType) {
            try {
                req.overrideMimeType(this.mimeType);
            } catch (e) {
                // Couldn't override MIME type -- IE6 or Opera?
            }
        }
        var self = this; // Fix loss-of-scope in inner function
        this.req.onreadystatechange = function() {
            var resp = null;
            if (self.req.readyState == 4) {
                switch (self.responseFormat) {
                    case 'text':
                        resp = self.req.responseText;
                        break;
                    case 'xml':
                        resp = self.req.responseXML;
                        break;
                    case 'object':
                        resp = req;
                        break;
                }
                if (self.req.status >= 200 && self.req.status <= 299) {
                    self.handleResp(resp);
                } else {
                    self.handleErr(resp);
                }
            }
        };
        this.req.send(this.postData);
    };
    
    this.setMimeType = function(mimeType) {
        this.mimeType = mimeType;
    };

    this.handleErr = function() {
        var errorWin;
        try {
            errorWin = window.open('', 'errorWin');
            errowWin.document.body.innerHTML = this.responseText;
        } catch (e) {
            alert('An error occurred, but the error message cannot be '
                + 'displayed. This is probably because of your browser\'s '
                + 'pop-up blocker.\n'
                + 'Please allow pop-up from this web site if you want to '
                + 'see the full error messages.\n'
                + '\n'
                + 'Status Code: ' + this.req.status + '\n'
                + 'Status Description: ' + this.req.statusText);
        }
    };
    
    this.setHandlerErr = function(funcRef) {
        this.handleErr = funcRef;
    };

    this.setHandlerBoth = function(funcRef) {
        this.handleResp = funcRef;
        this.handleErr = funcRef;
    };
    
    this.abort = function() {
        if (this.req) {
            this.req.onreadystatechange = function() { };
            this.req.abort();
            this.req = null;
        }
    };
    
    this.doGet = function(url, hand, format) {
        this.url = url;
        this.handleResp = hand;
        this.responseFormat = format || 'text';
        this.doReq();
    };
}