public function addProvisioner(ProvisionerInterface $provisioner, ProvisionerConfigurationInterface $configuration)
    {

        // bind the provisioner callback to the naming directory => the application itself
        $this->getNamingDirectory()->bind(sprintf('php:global/%s/%s', $this->getUniqueName(), $configuration->getName()), array(&$this, 'getProvisioner'), array($configuration->getName()));

        // add the provisioner instance to the application
        $this->provisioners[$configuration->getName()] = $provisioner;
    }