public function postCommand($name, array $params = null)
    {
        $uri = 'command';
        $uriData = [
            'name' => $name
        ];

        if ($params != null) {
        	foreach ($params as $key=>$value) {
        		$uriData[$key]= $value;
	        }
        }

        try {
            $response = $this->_request(
                [
                    'uri' => $uri,
                    'type' => 'post',
                    'data' => $uriData
                ]
            );
        } catch ( \Exception $e ) {
            throw new InvalidException($e->getMessage());
        }

        return $response->getBody()->getContents();
    }