Zend - Authentication

    public function authAction(){
        $request = $this->getRequest();
        $registry = Zend_Registry::getInstance();
        $auth = Zend_Auth::getInstance();
       
        $db = $registry['db'];
       
        $authAdapter = new Zend_Auth_Adapter_DbTable($db);
        $authAdapter->setTableName('users')
                    ->setIdentityColumn('username')
                    ->setCredentialColumn('password');
                   
        // set the input credential values
        $uname = $request->getParam('username');
        $passwd = $request->getParam('password');
        $authAdapter->setIdentity($uname);
        $authAdapter->setCredential(md5($passwd));
       
        // perform the auth query, saving the result
        $result = $auth->authenticate($authAdapter);
       
        if($result->isValid()){
            $data = $authAdapter->getResultRowObject(null, 'passwd');
            $auth->getStorage()->write($data);
            $this->_redirect('/user/userpage');
        }else{
            $this->_redirect('/user/loginform');
        }
    }
   
    public function userpageAction(){
        $auth = Zend_Auth::getInstance();
       
        if(!$auth->hasIdentity()){
            $this->_redirect('/user/loginform');
        }
       
        $request = $this->getRequest();
        $user = $auth->getIdentity();
        $real_name = $user->real_name;
        $username = $user->username;
        $url = $request->getBaseURL().'/user/logout';
       
        $this->view->assign('username', $real_name);
        $this->view->assign('url', $url);
       
    }
   
    public function logoutAction(){
        $auth = Zend_Auth::getInstance();
        $auth->clearIdentity();
        $this->_redirect('/user');
    }

Zend - Authentication