protected function buildHeader()
    {
        if ($this->getExtNamespace() === null) {
            throw new ExtDirectException("Ext js Namespace not set");
        }

        // Example: 'Ext.ns("Ext.app"); Ext.app.REMOTING_API = ';
        $var = 'Ext.ns("' . $this->getNameSpace() . '"); ' . $this->getNameSpace() . "." . Keys::EXT_HEADER . ' = ';

        return $var;
    }