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.handelResp = null;
  this.responseFormat = 'text';
  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
      }
    }
    var self = this;
    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;
        }
        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');
      errorWin.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-ups from this website if you want to ' +
             'see the full error message.\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();
  };
  
}