var xmlHttpReq=null;

function createxhr() {
  var xhr=null;
  try
  {
    xhr=new XMLHttpRequest();
    xhr.overrideMimeType('text/xml');
  }
  catch (e)
  {
  try
    {
    xhr=new ActiveXObject("Msxml2.XMLHTTP");
    }
    catch (e)
    {
      xhr=new ActiveXObject("Microsoft.XMLHTTP");
    }
  }
  return xhr;
}

function get_request_sync(strurl)
{ 
  var dt=null;
  if (xmlHttpReq==null) xmlHttpReq=createxhr();
  if (xmlHttpReq==null)
  {
    alert ("Your browser does not support AJAX!");
    return;
  } 
  try {
  dt=(function() {
    xmlHttpReq.open("GET",strurl,false);
    })();
    xmlHttpReq.send(null);
	dt=xmlHttpReq.responseText;
  }
  catch(e) {
    alert('Πρόβλημα στο δίκτυο...');
  }
    
  return dt;
}

function post_request_sync(strurl,strSubmit)
{ 
  var dt=null;
  if (xmlHttpReq==null) xmlHttpReq=createxhr();
  if (xmlHttpReq==null)
  {
    alert ("Your browser does not support AJAX!");
    return;
  } 
  try {
  dt=(function() {
    xmlHttpReq.open("POST",strurl,false);
    })();
    xmlHttpReq.send(strSubmit);
	dt=xmlHttpReq.responseText;
  }
  catch(e) {
    alert('Πρόβλημα στο δίκτυο...');
  }
    
  return dt;
}

function get_request(strurl,strResultFunc)
{ 
  if (xmlHttpReq==null) xmlHttpReq=createxhr();
  if (xmlHttpReq==null)
  {
    alert ("Your browser does not support AJAX!");
    return;
  } 
  xmlHttpReq.onreadystatechange=function() {
    if (xmlHttpReq.readyState == 4) {
      strResponse = xmlHttpReq.responseText;
      switch (xmlHttpReq.status) {
        case 404:
          alert('Error: Not Found. The requested URL ' + strURL + ' could not be found.');
		break;
        case 500:
          handleErrFullPage(strResponse);
        break;
        default:
          if (strResponse.indexOf('Error:') > -1 || strResponse.indexOf('Debug:') > -1) {
			alert(strResponse);
          }
          else {
            eval(strResultFunc + '(strResponse);');
          }
          break;
         }
      }
   }
  xmlHttpReq.open("GET",strurl,true);
  xmlHttpReq.send(null);
}

function handleErrFullPage(strIn) {
  var errorWin;
  try {
    errorWin = window.open('', 'errorWin');
    errorWin.document.body.innerHTML = strIn;
  }
  catch(e) {
    alert('An error occurred, but the error message cannot be' +
    ' displayed because of your browser\'s pop-up blocker.\n' +
    'Please allow pop-ups from this Web site.');
  }
}

function post_request(strURL, strSubmit, strResultFunc) {
  if (xmlHttpReq==null) xmlHttpReq=createxhr();
  if (xmlHttpReq==null)
  {
    alert ("Your browser does not support AJAX!");
    return;
  } 
  xmlHttpReq.open('POST', strURL, true);
  xmlHttpReq.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
  xmlHttpReq.onreadystatechange = function() {
  if (xmlHttpReq.readyState == 4) {
    strResponse = xmlHttpReq.responseText;
    switch (xmlHttpReq.status) {
      case 404:
        alert('Error: Not Found. The requested URL ' + strURL + ' could not be found.');
      break;
      case 500:
        handleErrFullPage(strResponse);
        break;
      default:
        if (strResponse.indexOf('Error:') > -1 || strResponse.indexOf('Debug:') > -1) {
          alert(strResponse);
        }
        else {
          eval(strResultFunc + '(strResponse);');
        }
        break;
      } 
    }
  }
  xmlHttpReq.send(strSubmit);
}        

function getQuery(sql) { 
  return eval('('+get_request_sync("queryinstance_json?sql="+sql)+')'); 
}