KR0133806B1 - File transfer method - Google Patents

Abstract

The present invention relates to a protocol of file transfer, and to solve the inconvenience of file transfer and the inconvenience of multi-stage transfer using a session different from the session established at the time of login as seen by the existing ftp. In other words, the special characters used by telnet used to log in are replaced with other characters, and the receiving side reduces the original characters and stores them. In addition, if an error occurs during the transfer, the file received up to that time is left unchanged, and only the next file is received to increase the transfer efficiency. Thus, the present invention enhances the convenience of communication by solving the session which is the passage of communication, using the session already established without making a separate file for file transfer only, and solving the multi-stage transmission in one step.

Description

File transfer method

1 is a diagram showing a conventional file transfer method,

2 is a flowchart illustrating a client-side execution process of the present invention.

3 is a flowchart showing a server-side execution process of the present invention,

4 is a detailed flowchart of file transmission on the transmitting side according to the present invention;

5 is a detailed flowchart of file transfer on the receiving side according to the present invention.

The present invention is to compensate for the shortcomings of the existing file transfer protocol (ftp) (file trasfer protocol) to ensure fast file transfer and file transparency (transparency). That is, the present invention relates to a file transfer between a computer and a computer or a file transfer between a terminal and a computer.

Ftp, a widely used file transfer protocol, does not use a telnet session after a user has logged in to the computer via telnet through a terminal. Only available to set. That is, in FIG. 1 assuming a LAN situation, a user can log in to computer 1 by running telnet in a terminal. This is a telnet session 1 is established between the terminal and the computer 1, and the communication between the terminal and the computer 1 through this session. In this situation, if the user wants to receive a file from computer 1 to the terminal, he or she must set up a separate session, ie, ftp session 1, to receive the file. The reason you should set up a separate session from the previous session is that telnet uses a group of characters as an escape sequence, so if you send a file via ftp in a telnet session, the group of characters in the file will be broken and the transparency of the file transfer Because it is not guaranteed. Therefore, to ensure the manageability of file transfer, a session must be set up separately from the session at login. This deteriorates the efficiency of transmission lines such as a local area network (LAN), and wastes bandwidth on the line.

In addition, when a user logs in to Computer 1 from the terminal and then logs into Computer 2, Telnet Session 2 is required between Computer 1 and Computer 2, in addition to the existing Telnet session. In this situation, if the user wants to receive a file from computer 2, an ftp session 2 is set up between computer 1 and computer 2. In other words, no direct session can be established between the terminal and computer2. This means that the terminal does not receive the file on computer 2 directly, but instead receives it on computer 1. In other words, it means a multi-stage transmission in which Computer 1 receives a file from Computer 2 and sends it back to the terminal. This is a huge waste of time and makes file transfer difficult. In an environment such as a LAN, especially in an environment in which files are distributed to various computers for distributed processing, waste of time and resources for file transfer is very serious.

The present invention seeks to address these drawbacks of existing file transfers. In other words, it provides a communication method that can guarantee the transparency of the file transfer while using the already set telesession. In other words, it is performed at the application layer without modification of the TCP / IP (Transmission Control Protocol / Internet Protocol) protocol to control the LAN in the existing LAN environment, which solves the inconvenience of multi-stage transmission and transparent file transfer in telnet sessions. It is intended to be done.

[Configuration of Invention]

In order to solve the above problems, it is necessary to use a telnet session that is already set up at the time of login, and transparent file transfer should be performed. The communication method for this will be described. First, prepare for client and server side transfer and reception. That is, when the user sets the sending status with the file name, inputs the command with the command name, or sets the file in the receiving status, the computer or terminal on the client side sends a synchronization signal to the server side and prepares to receive it. . The server side receives the synchronization signal received from the client side and starts transmission or reception.

First, the sender sends the name of the file to be sent and its size to the receiver. The receiving party checks whether it has a file that it has done, and sends the file size to 0 if it does not have the file, and the size of the file to the sender. If the file size of the receiving side is smaller than the file size of the transmitting side, the transmitting side, which has received the file size from the receiving side, proceeds to the transfer step and otherwise does not send the file. When the sender decides to send the file, it sends each character in the file one character at a time. When sending a character, the character that Telnet uses as the escape sequence is replaced with another character. This is to ensure the transparency of the file transfer. The receiving side determines whether the received character is a deformed character, that is, a substituted character, and if it is a substituted character, reduces and stores the original character.

On the other hand, if the receiver detects a problem with the transmission, the receiver transmits the size of the file stored up to the time it was received to the sender, thereby minimizing the retransmission by minimizing the retransmission by transmitting only the remaining part of the subsequent file. Allow the transfer to take place.

EXAMPLE

A specific embodiment of a file transfer protocol, that is, a file communication method configured in the above order will be described according to a flowchart.

First we define the signals required for this protocol.

DDLE: Controls transmission as the first signal to be transmitted.

DSYN: Sync signal for communication

DFILE: Signal to send file name

DSIZE: Signal to send file size or retransmission location

DRECO: Signal to go to the retransmission location of the file

DFIN: Signals that the file to be sent is not present, that is, the end of the protocol.

Also, if the character used as escape sequence in telnet exists in the file, it will not be transmitted properly. These problems include -1, 0, 15, 16, 17, 19, 22, 29, 157 and 255. DDLE is used as a communication control character in this communication method, so if it is in a file, the file will not be transferred properly. Therefore, the character group including these numbers and DDLE is defined as MASK.

On the other hand, when the character belonging to this MASK is transmitted, it is necessary to substitute another character for transmission and to reduce the original character to the original character. If the function for this substitution is defined as F, it can be defined as an example of this substitution function as follows.

F (-1) = '0'

F (0) '1'

F (15) = '2'

F (16) = '3'

F (17) = '4'

F (19) = '5'

F (22) = '6'

F (29) = '8'

F (157) = '9'

F (255) = 'A'

F (DDLE) = '7'

Here, the function value of F corresponds to the ASCII value of the character in ''.

Characters, etc. defined above are just one example and may be defined differently according to the embodiment, and the present invention is irrelevant to the essence.

One embodiment of the present invention will be described according to the flowchart using the above.

Before using this communication method, the client side transmits DDLE and DSYN as shown in FIG. 2 and performs this communication method. On the other hand, the server side receives the DDLE, DSYN sent from the receiving side as in the third and performs the present communication method.

4 shows a flowchart of the transmitting side. The sender first determines whether a file to be transmitted exists (A). If the file to be transmitted does not exist, the sender sends DDLE and DFIN to the receiver to inform the end of transmission (A1) and terminates the transmission. If there is a file to be sent, the file is opened (B), and the name and size of the file are sent to the receiver in the order of DDLE, DSIZE, name, size, DDLE, DSYN, and (C) the response. Receive. The response from the receiver is received in the order of DDLE, DSIZE, size, DDLE, DSYN (E), if the received file size is greater than or equal to the size of the send file, that is, the file is already greater than or equal to the send file to the receiver. If it exists, transmission of the file is stopped. On the other hand, if the size of the transmission file is larger than the size of the received file, adjust the file pointer indicating the position of the file to be transmitted (F) and read the character corresponding to the position (G), and the character is the file. If the EOF indicates the end of the transmission, DDLE and F (-1) are transmitted (H1), DDLE and DDLE are sent (H2) to inform the end of the transmission of the file, and when a response DDLE or DSYN is received (H3), The transmission of the file is terminated. On the other hand, if the character read from the transmission file is not EOF, it checks whether the character requires substitution (I), and if it needs to be replaced, sends the value substituted with DDLE (I1). ), And checks whether there is data sent from the receiving end (K), and if not, proceeds to sending the next character (G). On the other hand, if the received data exists and it is DDLE, DSIZE (L), the file size, DDLE, DSYN, which is the retransmission location is received (M), and DDLE, DRECO is sent to the receiver (N) to correct the receiving location. Go to the process of sending the next text (F). If the received data is not DDLE or DSIZE, the file transfer is recognized as the end of file transfer due to the circumstances of the receiver.

If the character to be transmitted is a character that hinders the transparency of the file transmission, it is replaced with another character and transmitted to facilitate the file transfer. In addition, when a signal indicating that an error occurs in the middle of a transmission is received from the receiving side, the file is not sent from the beginning, but only the data after the error occurs to improve the file transfer efficiency.

Meanwhile, the process of receiving a file on the receiving side will be described. 5 shows a communication method of file transfer on the receiving side, and thus the receiving process will be described accordingly. First, the receiving side resets the flag (A) and receives the character transmitted by the transmitting side (B). If there is an error during the transmission (C), if there is an error, the current position is stored (C1), and DDLE, DSIZE, file storage size, DDLE, and DSYN are sent to the sender (C2). It is a very advantageous communication method in terms of transmission efficiency and time if it is not notified.

Claims (3)

The transmission preparation step of determining whether to send a file by sending the name and size of the file to be sent to the receiver and receiving the size of the file as a response, and the sender sends one character of the file to be transmitted one by one, and the receiver checks and receives it. In the file transfer method using TCP / IP, which consists of a transmission step of storing data, the transmission step transmits by receiving a signal indicating that the transmitted character has been replaced by replacing it with another character when the sender transmits a special character, When the side receives a signal indicating that the transmitted character has been replaced, the transmitted character is returned to the original character and stored. The file transfer method according to claim 1, wherein when the receiving side finds out that there is an error in character reception, the transmitting side transmits the character after the current position of the receiving side. The file transfer method according to claim 1, wherein the special character to be replaced and returned is a character used in an escape sequence.