// Ajax functions
  // (c) joe marini 2005
  
  var xmlhttp = null; // the XMLHttpRequest object
  
  function createRequest()
  {   
          var reqObj = null;
          try {
                  reqObj = new ActiveXObject("Msxml2.XMLHTTP");
          }
          catch (err)        {
                  try {
                          reqObj = new ActiveXObject("Microsoft.XMLHTTP");
                  }
                  catch (err2) {
                          try {
                                  reqObj = new XMLHttpRequest();
                          }
                          catch (err3) {
                                  reqObj = null;
                          }
                  }
          }
          return reqObj;
  }
  
  function getURL(url, callback, isAsync)
  {    
          // if the request is already executing then stop it (executing means in  a state
          // other than 0 (uninitialized) or 4 (completed).
          if (xmlhttp != null) {
                  if (xmlhttp.readyState != 4 && xmlhttp.readyState != 0)
                          xmlhttp.abort();
          }  
          xmlhttp = createRequest();  
          if (xmlhttp != null) {  
                  alert("ajax.js :getURL:"+url+"\n\ncallback:"+callback+"\n\nxmlxmlhttp);
                  xmlhttp.open('GET', url, isAsync);  
                  xmlhttp.onreadystatechange=callback;
                  xmlhttp.send(null);
          }  
           
  }
  
  function postURL(url, callback, isAsync, data)
  {
          // if the request is already executing then stop it (executing means in  a state
          // other than 0 (uninitialized) or 4 (completed).
          if (xmlhttp != null) {
                  if (xmlhttp.readyState != 4 && xmlhttp.readyState != 0)
                          xmlhttp.abort();
          }
          
          xmlhttp = createRequest();
          if (xmlhttp != null) {
                  xmlhttp.open("POST", url, isAsync);
                  xmlhttp.onreadystatechange=callback;
                  xmlhttp.send(data);
          }
  }