protected function initBackend()
    {
        $this->backendList = array();
        $this->balancedBackendList = array();

        foreach ($this->getConfigArrayOption('backend', array()) as $backendName => $option) {
            if (!isset($option['ip']) || !isset($option['port'])) {
                continue;
            }

            $this->backendList[$backendName] = array($option['ip'], $option['port']);
            if (!empty($option['balanced'])) {
                $this->balancedBackendList[] = $backendName;
            }

            if (!empty($option['admin'])) {
                $this->adminBackend = $backendName;
            }
        }

        if ($this->adminBackend === null) {
            $this->adminBackend = key($this->backendList);
        }

        return $this;
    }