private function _buildPlugins()
    {
        $pluginroot = $this->_xml->addChild("Plugins");
        if (($this->_plugin_request || $this->_complete_request) && count($this->_plugins) > 0) {
            $plugins = array();
            if ($this->_complete_request) {
                $plugins = $this->_plugins;
            }
            if ($this->_plugin_request) {
                $plugins = array($this->_plugin);
            }
            foreach ($plugins as $plugin) {
                $object = new $plugin($this->_sysinfo->getEncoding());
                $object->execute();
                $oxml = $object->xml();
                if (sizeof($oxml) > 0) {
                    $pluginroot->combinexml($oxml);
                }
            }
        }
    }