How to grab versions from XML

$latest_version == '?.?.?';
$content = self::getRemoteData('http://www.joomace.net/index.php?option=com_aceversions&view=xml&format=xml');

if (strstr($content, '')) {
   $xml =& JFactory::getXMLparser('Simple');
   $xml->loadString($content);

   foreach ($xml->document->children() as $category) {
      $catname = $category->attributes('name');
      if ($catname == 'components') {
         foreach ($category->children() as $extension) {
           $option = $extension->attributes('option');
           if ($option == 'com_acesef') {
              $latest_version = trim($extension->attributes('version'));
              break;
           }
         }
         break;
      }
   }
}

You can also append the &catid=6 to the XML link so that just the extensions of that category will be grabbed.

And this is the getRemoteData function which uses cURL, fsockopen, fopen and file_get_content PHP functions to grab remote data (just copy-paste it, zero-changes needed):

function getRemoteData($url) {
  $useragent = "Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 3.5.30729)";
  $data = false;

  // cURL
  if (extension_loaded('curl')) {
   // Init cURL
   $ch = @curl_init();
   
   // Set options
   @curl_setopt($ch, CURLOPT_URL, $url);
   @curl_setopt($ch, CURLOPT_HEADER, 0);
   @curl_setopt($ch, CURLOPT_FAILONERROR, 1);
   @curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
   @curl_setopt($ch, CURLOPT_USERAGENT, $useragent);
   
   // Set timeout
   @curl_setopt($ch, CURLOPT_TIMEOUT, 5);
   
   // Grab data
   $data = @curl_exec($ch);
   
   // Clean up
   @curl_close($ch);
   
   // Return data
   if ($data !== false) {
    return $data;
   }
  }

  // fsockopen
  if (function_exists('fsockopen')) {
   $errno = 0;
   $errstr = '';
   
   $url_info = parse_url($url);
   if($url_info['host'] == 'localhost')  {
    $url_info['host'] = '127.0.0.1';
   }

   // Set timeout
   $fsock = @fsockopen($url_info['scheme'].'://'.$url_info['host'], 80, $errno, $errstr, 5);
  
   if ($fsock) {
    @fputs($fsock, 'GET '.$url_info['path'].(!empty($url_info['query']) ? '?'.$url_info['query'] : '').' HTTP/1.1'."\r\n");
    @fputs($fsock, 'HOST: '.$url_info['host']."\r\n");
    @fputs($fsock, "User-Agent: ".$useragent."\n");
    @fputs($fsock, 'Connection: close'."\r\n\r\n");
  
    // Set timeout
    @stream_set_blocking($fsock, 1);
    @stream_set_timeout($fsock, 5);
    
    $data = '';
    $passed_header = false;
    while (!@feof($fsock)) {
     if ($passed_header) {
      $data .= @fread($fsock, 1024);
     } else {
      if (@fgets($fsock, 1024) == "\r\n")
       $passed_header = true;
     }
    }
    
    // Clean up
    @fclose($fsock);
    
    // Return data
    if ($data !== false) {
     return $data;
    }
   }
  }

  // fopen
  if (function_exists('fopen') && ini_get('allow_url_fopen')) {
   // Set timeout
   if (ini_get('default_socket_timeout') < 5) {
    ini_set('default_socket_timeout', 5);
   }
   @stream_set_blocking($handle, 1);
   @stream_set_timeout($handle, 5);
   @ini_set('user_agent',$useragent);
   
   $url = str_replace('://localhost', '://127.0.0.1', $url);
   
   $handle = @fopen ($url, 'r');
   
   if ($handle) {
    $data = '';
    while (!feof($handle)) {
     $data .= @fread($handle, 8192);
    }
    
    // Clean up
    @fclose($handle);
   
    // Return data
    if ($data !== false) {
     return $data;
    }
   }
  }
  
  // file_get_contents
  if(function_exists('file_get_contents') && ini_get('allow_url_fopen')) {
   $url = str_replace('://localhost', '://127.0.0.1', $url);
   @ini_set('user_agent',$useragent);
   $data = @file_get_contents($url);
   
   // Return data
   if ($data !== false) {
    return $data;
   }
  }
  
  return $data;
}