Abstract: Disclosed is a method for transferring a message file from a client to a server over the Internet. When message file transfer is stopped after the client initiates the message file transfer to the server, the client sending a request for information of the transfer-stopped message file to the server. The server provides the transfer-stopped message file information to the client in response to the file information request. The client carrying out an upload resumption function to upload transfer-stopped partial contents of the message file to the server according to the transfer-stopped message file information provided from the server.

Abstract: Disclosed is a waste heat recovery system with a cleaning apparatus, which can effectively recover waste heat and easily clean the system, thereby increasing heat exchange efficiency and making its maintenance easy.