gistfile1.php

1. Controller: http://www.example.com/

<?php

class IndexController extends Zend_Controller_Action
{
  public function indexAction()
  {
   
      if(!Zend_Feed_Reader::isRegistered('JungleBooks')) {
   
          Zend_Feed_Reader::addPrefixPath(
              '/var/www/html/zendframework/application/My/FeedReader/Extension', 'My_FeedReader_Extension'
          );

          Zend_Feed_Reader::registerExtension('JungleBooks');

      }

  }
}


2. File exist here: /var/www/html/zendframework/application/My/FeedReader/Extension/JungleBooks.php
<?php
class My_FeedReader_Extension_JungleBooks_Entry extends Zend_Feed_Reader_Extension_EntryAbstract
{

    public function getIsbn()
    {
        if (isset($this->_data['isbn'])) {
            return $this->_data['isbn'];
        }

        $isbn = $this->_xpath->evaluate(
            'string(' . $this->getXpathPrefix() . '/jungle:isbn)'
        );

        if (!$isbn) {
            $isbn = null;
        }

        $this->_data['isbn'] = $isbn;
        return $this->_data['isbn'];

    }



    protected function _registerNamespaces()
    {
        $this->_xpath->registerNamespace(
            'jungle', 'http://example.com/junglebooks/rss/module/1.0/'
        );
    }

}

3. Application error

object(Zend_Feed_Exception)#35 (8) {
  ["_previous":"Zend_Exception":private]=>
  NULL
  ["message":protected]=>
  string(113) "Could not load extension: JungleBooksusing Plugin Loader. Check prefix paths are configured and extension exists."
  ["string":"Exception":private]=>
  string(0) ""
  ["code":protected]=>
  int(0)
  ["file":protected]=>
  string(47) "/var/www/html/zendframework/library/Zend/Feed/Reader.php"
  ["line":protected]=>