This would allow you to receive an acknowledgment of the message or receipt of delivery even if the response message is empty.
这样，即使响应消息为空，您也能够收到一个消息的确认或者交付收据。
2
The basic method for achieving reliable delivery is for the sender to send the message repeatedly to the target until the target acknowledges receipt of the message.
实现可靠传递的基本方法是发送方反复向目标方发出消息直到目标方确认收到消息。
3
The receiving application then decrypts the message upon receipt, converting from ciphertext back to plain text.