composer
kriswallsmith
payum
    \core
    \paypal-<whatever I wrote in the composer.json file>
    \payum-yii-extension

[alexandernst@stupidbox 0s PayumYiiExtension]$ composer update payum/payum-yii-extension payum/paypal-express-checkout-nvp payum/paypal-ipn 
Loading composer repositories with package information
Updating dependencies (including require-dev)
  - Installing kriswallsmith/buzz (v0.10)
    Loading from cache

  - Installing payum/core (0.9.2)
    Loading from cache

  - Installing payum/paypal-express-checkout-nvp (0.9.0)
    Loading from cache

  - Installing payum/paypal-ipn (0.9.0)
    Loading from cache

payum/core suggests installing payum/paypal-pro-checkout-nvp (If you want to use paypal pro checkout)
payum/core suggests installing payum/paypal-rest (If you want to use paypal rest gateway)
payum/core suggests installing payum/authorize-net-aim (If you want to use Authorize.Net AIM payment gateway)
payum/core suggests installing payum/be2bill (If you want to use be2bill payment gateway)
payum/core suggests installing payum/payex (If you want to use payex payment gateway)
payum/core suggests installing payum/omnipay-bridge (If you want to use omnipay's gateways)
payum/core suggests installing doctrine/orm (If you want to store models to database using doctrin2 ORM)
payum/core suggests installing doctrine/mongodb-odm (If you want to store models to mongo doctrin2 ODM)
payum/core suggests installing zendframework/zend-db (If you want to store models to Zend Db ORM)
payum/core suggests installing symfony/routing (If you want to use TokenFactory from symfony's bridge)
payum/core suggests installing symfony/http-kernel (If you want to use HttpRequestVerifier from symfony's bridge)
payum/core suggests installing symfony/http-foundation (If you want to use HttpRequestVerifier or ResponseInteractiveRequest from symfony's bridge)
payum/core suggests installing monolog/monolog (In case you want to use logger)
Writing lock file
Generating autoload files

ReflectionException

Property PaymentDetails::$payum_id does not exist

/............/extensions/PayumYiiExtension/vendor/payum/core/Payum/Core/Storage/FilesystemStorage.php(95)

083 
084         if ($id = $rp->getValue($model)) {
085             unlink($this->storageDir.'/payum-model-'.$id);
086             unset($this->identityMap[$id]);
087         }
088     }
089 
090     /**
091      * {@inheritDoc}
092      */
093     protected function doGetIdentificator($model)
094     {
095         $rp = new \ReflectionProperty($model, $this->idProperty);
096         $rp->setAccessible(true);
097 
098         if (false == $id = $rp->getValue($model)) {
099             throw new LogicException('The model must be persisted before usage of this method');
100         }
101 
102         return new ModelIdentificator($id, $model);
103     }
104 }