public function appendObject($bucket, $object, $content, $position, $options = NULL)
    {
        $this->precheckCommon($bucket, $object, $options);

        $options[self::OSS_CONTENT] = $content;
        $options[self::OSS_BUCKET] = $bucket;
        $options[self::OSS_METHOD] = self::OSS_HTTP_POST;
        $options[self::OSS_OBJECT] = $object;
        $options[self::OSS_SUB_RESOURCE] = 'append';
        $options[self::OSS_POSITION] = strval($position);

        if (!isset($options[self::OSS_LENGTH])) {
            $options[self::OSS_CONTENT_LENGTH] = strlen($options[self::OSS_CONTENT]);
        } else {
            $options[self::OSS_CONTENT_LENGTH] = $options[self::OSS_LENGTH];
        }
        
        $is_check_md5 = $this->isCheckMD5($options);
        if ($is_check_md5) {
        	$content_md5 = base64_encode(md5($content, true));
        	$options[self::OSS_CONTENT_MD5] = $content_md5;
        }

        if (!isset($options[self::OSS_CONTENT_TYPE])) {
            $options[self::OSS_CONTENT_TYPE] = $this->getMimeType($object);
        }
        $response = $this->auth($options);
        $result = new AppendResult($response);
        return $result->getData();
    }