public function init()
{
$options = $this->getInvokeArg('bootstrap')->getOption('twitter');
$options['callbackUrl'] = $this->_getCallbackUri();
// workaround since INI config cannot define a NULL value :(
$this->_helper->getHelper('Cache')->setTemplateOptions('twitter', array('frontend' => array('options' => array('lifetime' => null))));
$this->_cache = $this->_helper->getHelper('Cache')->getCache('twitter');
$this->_consumer = new Zend_Oauth_Consumer($options);
}