JPH11272573A - File transfer method, file transfer system and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently transfer a data file by minimizing increase of overhead when a communication channel is cut off. SOLUTION: A file to be transferred is transferred as plural divided blocks to be constituted by successively dividing the file from the head by specified amount and adding a block name and error inspection information to each of divided data and reconstructed at the receiving side. Transfer of the divided blocks is one-sidedly performed from the transmitting side to the receiving side until transmission of all the blocks completes or the communication channel C is cut off. And when the communication channel C is cut off by the transmitting side according to completion of transmission of all blocks or the communication line is cut off due to abnormality, etc., of the communication line C, if the divided block in which a transmission error occurs or the divided block which is not yet received exists in the divided block received at the receiving side so far, these blocks are transferred from the transmitting side according to a request from the receiving side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a file transfer method for transferring a file between two terminals connected to each other via a communication line, a file transfer system to which the file transfer method is applied, and a file transfer method. The present invention relates to a storage medium storing an operation program for causing an electronic computer to perform an operation for implementing a transfer system.

[0002]

2. Description of the Related Art As shown in FIG. 13, a plurality of terminals T are connected via a communication network NT composed of, for example, a wired communication network NTa and a wireless communication network NTb, and each terminal T arbitrarily transmits and receives data files. There is a collaborative work system that performs a predetermined work while performing the work.

Conventionally, data transfer between terminals in such a system is performed by generating a divided block from a data file, executing transmission, and performing error control (validity confirmation, retransmission request,
Resend), reconstructing files, and so on.

If the communication line is disconnected during the file transfer, all of the data including the portion transferred normally is discarded, and all the divided blocks are transmitted from the beginning after the line is connected again. Had become.

[0005] For this reason, there is a problem that overhead due to retransmission is large. In particular, when the quality of the communication line is inferior, for example, via the wireless communication network NTb, the overhead becomes very large, and a long time is required for the file transfer. In the worst case, the file transfer is executed. There was a problem that it could not be done.

[0006]

As described above, conventionally,
When the communication line is disconnected, there is a problem that the overhead becomes very large in order to restart the data transfer operation which has caused the increase of the overhead because of error control or the like.

The present invention has been made in view of such circumstances, and an object of the present invention is to minimize the increase in overhead when a communication line is disconnected and to efficiently reduce data. An object of the present invention is to enable file transfer.

[0008]

In order to achieve the above object, according to the present invention, a transmitting terminal divides data of a transfer target file in order from a head for each predetermined amount, and divides the data of these files. For example, a plurality of divided blocks obtained by adding predetermined position information such as a block name indicating a position in the transfer file and predetermined error check information enabling a check for the presence or absence of a transmission error to each of the data, Divided by the dividing means, and the plurality of divided blocks are sequentially transmitted by, for example, the divided block transmitting means until all the transmission is completed or the communication line is disconnected, and all of the divided blocks are transmitted. In response to the completion, the communication line is disconnected by, for example, the line disconnection control unit and the network control unit, and the transmission of the divided blocks is temporarily stopped. If transmission of the divided blocks from the receiving terminal to the Chi is requested, sends the requested divided blocks, for example by response request transmission control means.

The receiving terminal receives the divided block arriving via the communication line by, for example, divided block receiving means, and determines whether or not there is a transmission error in the received divided block by using the error check information. Inspection by error checking means, after the communication line is disconnected, requesting the transmission side terminal to transmit a divided block or an unreceived divided block determined to be erroneous by the inspection, for example, by transmission requesting means, If all the divided blocks have been received without error when the communication line is disconnected, the completion of the transfer is notified to the transmitting side terminal by, for example, a transfer completion notifying means, and further, the division that can be received without error is transmitted. The transfer target file is reconstructed by, for example, a file reconstructing means by combining blocks.

[0010] By adopting such means, the transfer target file is divided in order from the beginning by a predetermined amount, and each of the divided data has a predetermined block indicating a position in the transfer file. The information is transferred as a plurality of divided blocks to which position information such as a name and predetermined error check information enabling the presence or absence of a transmission error to be added are reconstructed on the receiving side.

The transfer of the divided block is performed unilaterally from the transmitting side to the receiving side until all the transmissions are completed or the communication line is disconnected. If the communication line is disconnected by the transmitting side in response to the completion of all transmissions, or the communication line is disconnected due to an abnormality in the communication line, etc., a transmission error is received in the divided block received so far. If there is a divided block in which has occurred, or there are unreceived divided blocks, those divided blocks are
It is transferred from the transmitting side in response to a request from the receiving side.

Therefore, even if the communication line is disconnected due to an abnormality in the communication line during the transfer of the divided block, thereafter, only the divided block that has not been properly received on the receiving side is transferred.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a functional block diagram showing a main configuration of a terminal device for realizing the file transfer system according to the present embodiment.

The file transfer system according to the present embodiment is constructed by preparing a plurality of terminal devices shown in this figure and using them as the terminal T in FIG.

[0016] As shown in FIG.
It has a storage unit 2, an input unit 3, a display unit 4, a modem unit 5, and a network control unit 6.

The control unit 1 is connected with a storage unit 2, an input unit 3, a display unit 4, a modem unit 5 and a network control unit 6, and these units are collectively controlled to connect with other terminal devices. An operation as a terminal device that performs file transfer between the terminals is realized.

The storage unit 2 includes, for example, a hard disk device or the like.
Stores various data necessary for performing various processes.

The input unit 3 uses, for example, a keyboard or the like, and receives an instruction input to the control unit 1 by a user.

The display unit 4 includes, for example, a CRT or an LCD, and performs display for notifying information to the user.

The modulation / demodulation unit 5 modulates data to be transferred to another terminal device into a transmission signal that can be transmitted via a communication network, and demodulates a transmission signal arriving via the communication network to generate data. To play.

The network control unit 6 is connected to the communication network and controls connection / disconnection of the communication line C connected to the terminal device, and performs line state monitoring processing such as disconnection detection.

The control unit 1 comprises, for example, a personal computer main body, and has a control function for file transfer by causing its CPU to perform processing in accordance with a predetermined operation program. ing.

The control functions of the control unit 1 include:
There is a file transmission control function 11 for causing the terminal device to function as a file transmission terminal, and a file reception controller 12 for causing the terminal device to function as a file reception terminal.

The file transmission control function 11 further includes a file division unit 11a, a divided block transmission unit 11b, a line disconnection control unit 11c, and a request transmission control unit 11d.
have. Here, the file dividing means 11a divides the data file to be transferred to another terminal device into a plurality of data files and adds predetermined management information to create divided blocks. The divided block transmitting unit 11b performs a process for transmitting the divided block created by the file dividing unit 11a to the transfer destination terminal device. The line disconnection control unit 11c performs processing for disconnecting the communication line in response to transmission of all divided blocks by the divided block transmission unit 11b. Then, the request transmission control unit 11d performs a process for transmitting the specified divided block in response to a request for transmission of the untransferred block from the terminal device of the file transfer destination.

On the other hand, the file reception control function 12 further comprises a divided block receiving means 12a, an error checking means 12
b, transmission request means 12c, transfer completion notifying means 12d, and file restructuring means 12e. Here, the divided block receiving means 12a performs a process for receiving the divided block arriving via the communication line. The error checking unit 12b checks whether a transmission error has occurred for each of the divided blocks received by the divided block receiving unit 12a. Transmission request means 12c
Requests the transmission-side terminal device to transmit a divided block whose transfer has not been completed because it has not arrived yet or a received but transmission error has occurred. When all the divided blocks have been normally received, the transfer completion notifying unit 12d notifies the transmitting-side terminal device of the fact. Then, the file restructuring means 12e
The transfer file is reconstructed using the divided blocks that can be received normally.

Next, the operation when file transfer is performed between the terminal devices configured as described above will be described.

First, a control unit 1 in a terminal device for transmitting a data file (hereinafter referred to as a transmitting terminal).
Executes a file transmission process as shown in FIG. 2 by the file transmission control function 11.

In this file transmission process, the control unit 1 on the transmission side first creates a divided block by the file dividing means 11a (step ST1).

That is, as shown in FIG. 3, the control unit 1 on the transmitting side stores a data file (original file) to be transferred,
It is divided into a plurality of units each having a size of a predetermined transfer unit (for example, about 500 bytes). Then, with respect to these divided data, identification information (hereinafter, referred to as a block name) which can be uniquely identified and shows mutual relation, and verification information for verifying validity are provided. Divided data is created by adding. The split data created in this way is
It is stored in the storage unit 2. As the block name, for example, the original file name of the data file to be transferred to which a sequence number is added can be used. As the verification information, for example, a CRC code for verifying a data error of the block, a sequence number indicating the order of the block, and the like can be used.

The data divided from the data file may be inserted into the divided blocks after being subjected to compression processing and encryption processing. Further, the divided block may include additional information such as the block name of the next divided block.

When the creation of the divided blocks is completed, the control unit 1 on the transmitting side controls the network control unit 6 to perform a calling process to the terminal device on the receiving side (hereinafter, called the receiving side terminal) (step S1). ST2) Connect a communication line with the receiving terminal.

When the communication line is connected, the control unit 1 on the transmitting side
Starts transmission of divided blocks by the divided block transmitting means 11b (step ST3). When the transmission of the divided blocks is started in this way, the control unit 1 on the transmission side reads the divided blocks in order from the beginning and sends the divided blocks to the communication line C via the modem unit 5 and the network control unit 6, that is, to the receiving terminal. Send sequentially. Note that error control when transferring each divided block may or may not be performed.

In the state where the divided blocks are being transmitted, the control unit 1 on the transmitting side waits for the transmission of all the divided blocks to be completed or for the line to be disconnected (steps ST4 and ST5). ).

Here, when the transmission of all the divided blocks is completed, the control unit 1 on the transmitting side sends the line disconnection control unit 11
In step c6, the network controller 6 is controlled to disconnect the line. On the other hand, if the network control unit 6 detects that the line has been disconnected before the transmission of all the divided blocks is completed, the transmission of the divided blocks is stopped at that time (step ST7).

After the line is disconnected in step ST6 or the transmission is stopped in step ST7, the controller 1 on the transmitting side reconnects the communication line with the receiving terminal, and notifies the completion of transfer via this communication line. Alternatively, it waits for a transmission request to arrive (step ST8 and step ST8).
9).

In the receiving terminal, the control unit 1
When a call is received from the transmitting terminal, an incoming call response or the like is performed to establish a line connection, and a file reception process as shown in FIG.

In this file receiving process, the control unit 1 on the receiving side first starts receiving divided blocks arriving via the communication line C by the divided block receiving means 12a (step ST21). When the reception of the divided blocks is started in this way, the control unit 1 on the receiving side receives the divided blocks demodulated by the modem unit 5 from the modem unit 5 and accumulates them in the storage unit 2.

While receiving the divided blocks in this way, the control unit 1 on the receiving side monitors whether the line has been disconnected (step ST22).

In this state, the line is disconnected from the transmitting terminal as described above, or the line is disconnected due to a failure in the communication network, and if the line is detected by the network control unit 6, the control of the receiving side is performed. The unit 1 stops receiving the divided blocks (step ST23), and performs the validity verification process on the divided blocks received so far by the error checking unit 12b (step ST24). That is, the receiving terminal continues to receive the incoming divided block until the line is disconnected, regardless of whether or not the incoming divided block is valid.

In this validity verification process, the control unit 1 on the receiving side
Verifies the validity (presence or absence of a transmission error) of each divided block by using verification information for validity verification added to each divided block. Note that as a result of the validity verification, for the divided blocks determined to have been successfully received, the fact is recorded in the reception history information file in the storage unit 2.

When the validity verification process is completed,
The control unit 1 on the receiving side controls the network control unit 6 to perform a calling process for the transmitting terminal (step ST25), and reconnects the communication line with the transmitting terminal.

When the communication line is connected, the control unit 1 on the receiving side
Refers to the result of the validity verification in step ST25,
It is determined whether all the divided blocks created from one data file have been normally received (step ST26).

Here, in the case where the data cannot be normally received due to a transmission error in the transferred divided block, or there is a divided block which has not been transferred due to interruption of transmission due to disconnection of the line. Then, the control unit 1 on the receiving side requests the transmitting side terminal to transmit such divided blocks whose transfer has not been completed by the transmission requesting unit 12c (step ST27).

As described above, when the transmission of the untransferred block is requested from the receiving terminal, the control unit 1 on the transmitting side is in the standby state of step ST8 and step ST9 as described above. Therefore, when the transmission of the untransferred block is requested, the control unit 1 on the transmission side determines in step ST9 that the transmission request has arrived. Then, at this time, the control unit 1 on the transmission side starts transmission of the divided block designated by the reception side terminal by the request transmission control unit 11d (step ST10), and thereafter, repeats the processing after step ST4.

The control unit 1 on the receiving side performs step ST2.
After requesting the transmission of the transfer-uncompleted block in step 7, the processing after step ST21 is repeated to receive the divided block transmitted from the transmitting terminal in response to the request as described above. At this time, the control unit 1 on the receiving side compares the information with the already received normal received divided blocks recorded in the received history information file, and accumulates only the unreceived divided blocks.

If it is determined in step ST26 that all the divided blocks created from one data file have been successfully received by such processing, the control unit 1 on the receiving side transmits a transfer completion notification indicating this fact. Is transmitted to the transmitting terminal by the transfer completion notifying means 12d (step ST28).

When the transfer completion notification is transmitted from the receiving terminal in this way, the control unit 1 on the transmitting side is in the standby state of step ST8 and step ST9 as described above. Therefore, when the transfer completion notification arrives, the control unit 1 on the transmitting side
Recognizes that in step ST8. Then, at this time, the control unit 1 on the transmission side transmits a transfer completion notification response indicating that the transfer completion notification has been received to the reception side terminal (step ST11), and thereafter ends the file transmission process.

On the other hand, the control unit 1 on the receiving side performs the processing in step ST
After transmitting the transfer completion notification in step 28, it waits for the arrival of the transfer completion notification response (step ST29). Therefore, if the transmission completion notification response is transmitted from the transmitting terminal as described above, the control unit 1 on the receiving side transmits the response to step S
Recognize at T9. In this case, the control unit 1 on the receiving side reconstructs the data file by the file reconstructing means 12e using the divided blocks accumulated in the storage unit 2 as shown in FIG. 3 (step ST30). Thereafter, the file reception process ends.

When the transmitting-side control unit 1 and the receiving-side control unit 1 complete the file transmission processing and the file reception processing in this way, the divided blocks are stored in the storage unit 2 as necessary. To delete.

Thus, the terminal device as the transmitting terminal and the terminal device as the receiving terminal perform the above-described operations, so that file transfer can be performed in several patterns as follows according to the transfer state of the divided blocks. Will be done.

(Case 1: No transmission error of divided block, no line disconnection during transfer) In such a case, file transfer is performed in a sequence as shown in FIG.

That is, in response to the completion of the transfer up to the final divided block without disconnection of the line, the transmitting terminal disconnects the line. As a result, the disconnection of the line is detected for the first time at the receiving terminal, and the validity is verified (first transfer sequence).

As a result of the validity verification, it is determined that all the divided blocks have been normally received. Therefore, the line is reconnected by a request from the receiving terminal, and the line is reconnected from the receiving terminal to the transmitting terminal. A transfer completion notification is issued. Then, in response to this, the transmitting terminal sends a transfer completion notification response, thereby completing the file transfer procedure (end sequence).

(Case 2: There is a transmission error in a divided block, and there is no line disconnection during transfer) In such a case, file transfer is performed in a sequence as shown in FIG.

That is, the initial transfer sequence is the same as in Case 1 described above.

However, as a result of the validity verification, an erroneous divided block is detected, so that the following retransmission sequence is performed.

In this retransmission sequence, a transmission request for an erroneous divided block, that is, a retransmission request for an erroneous divided block is given from the receiving terminal to the transmitting terminal. Then, in response to the transmission request, the transmission-side terminal transfers the designated divided block, that is, retransmits the erroneous divided block.

When the transfer of all the designated divided blocks is completed without the disconnection of the line, the transmitting terminal disconnects the line. As a result, the disconnection of the line is detected at the receiving terminal, and the validity of the retransmitted divided block is verified.

As a result of validity verification, if it is determined that all the divided blocks have been received normally,
The termination sequence is performed as in the case of 1.

If a transmission error occurs in the retransmitted divided block, the retransmission sequence is repeated before the execution of the end sequence.

(Case 3: No transmission error of divided block, line disconnection during transfer) In such a case, file transfer is performed in a sequence as shown in FIG.

That is, the initial transfer sequence is the same as in the case 1 described above, except that the communication line is disconnected due to a failure in the physical communication line or deterioration of the radio wave condition in the wireless communication line section. Transfer of the divided block ends abnormally.

Even in the case of such an abnormal termination, the receiving terminal performs the validity verification by detecting the disconnection of the line.

Then, as a result of the validity verification, an untransferred divided block is detected, and the following untransferred block transfer sequence is performed.

In the untransferred block transfer sequence, a transmission request for a non-transferred divided block is given from the receiving terminal to the transmitting terminal. Then, in response to this transmission request, the transmission side terminal transfers the designated divided block, that is, transfers the untransferred block.

When the transfer of all the designated divided blocks is completed without disconnection, the transmitting terminal disconnects the link. As a result, the disconnection of the line is detected at the receiving terminal, and the validity of the transferred divided block is verified.

As a result of validity verification, if it is determined that all divided blocks have been received normally,
The termination sequence is performed as in the case of 1.

As described above, according to the present embodiment, the divided blocks are unilaterally transferred from the transmitting terminal to the receiving terminal until the transfer of all the divided blocks is completed or the line disconnection occurs. . When the transmission of all the divided blocks is completed, the transmitting terminal temporarily disconnects the line in order to activate the validity verification in the receiving terminal.

The receiving terminal only receives and stores the divided blocks until the line disconnection occurs, and if the line disconnection occurs, verifies the validity of the divided blocks received so far and transmits the data. It requests the transmitting terminal to transmit a divided block that has not been received normally due to an error or untransfer, and receives the transmitted divided block.

As described above, when the line is disconnected, the transfer of a one-sided divided block is performed before that, and only the divided blocks that cannot be normally received by the receiving terminal after that are requested by the receiving terminal. Even if a line disconnection occurs due to a line abnormality, the divided block normally received by the receiving terminal is still valid, and after the line is reconnected, the receiving terminal Since only the divided blocks that have not been received normally are transferred, an increase in overhead can be suppressed.

Therefore, if the present embodiment is used for file transfer via a communication network having an unstable line condition, efficient file transfer can be performed.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the data file is reconstructed after the normal reception of all the divided blocks is completed. The reconstruction of the data file using only the data file may be provisionally performed.

FIG. 8 is a sequence diagram showing an example of a sequence in a case where the data file is reconstructed tentatively using only some of the divided blocks which can be normally received.

In this figure, the retransmission sequence is executed because there is a divided block in which a transmission error has occurred in the initial transmission sequence. Before executing the retransmission sequence, the file restructuring and the file restructuring are performed. The used divided block is deleted from the storage unit 2.
In the file rebuilding prior to the execution of the retransmission sequence, for example, as shown in FIG. 9, an intermediate file is constructed in which a position corresponding to a divided block in which a transmission error has occurred is blank. Then, the complete reconstructed file is constructed by inserting the divided blocks transferred in the retransmission sequence into the intermediate file.

In the above embodiment, the transfer of the divided blocks is performed after all the divided blocks have been created. However, the blocks having the size of the sequential transfer unit are extracted from the data file while being created. The divided blocks obtained may be transferred.

In the above embodiment, the validity verification of the divided block is performed after the line is disconnected. However, the validity verification may be performed in parallel with the operation of receiving the divided block.

FIG. 10 is a sequence diagram showing an example of a sequence in which the creation and transfer of the divided blocks are performed in parallel, and the validity verification and the reconstruction of the data file are performed in parallel with the operation of receiving the divided blocks. FIG.

Further, in the example of FIG. 10, the divided blocks that cannot be received normally when the line is disconnected are verified by verifying the file (intermediate file) being reconstructed, so that the divided blocks that cannot be received normally, that is, are transferred. Is calculated.

It is also possible to perform file transfer in the sequence shown in FIG. 11 and FIG.

FIG. 11 shows that the transmitting terminal transfers the transfer target file while extracting the divided blocks, and the receiving terminal separates the received blocks individually or combines a plurality of blocks into one. When uniquely and mutually recognizable identification information is assigned as a file name, stored in an auxiliary storage device such as a hard disk, and the validity of the block received after the communication line is disconnected and the file is reconstructed Is a representative sequence.

FIG. 12 shows a case where the transmission-side terminal divides the transfer target file prior to transfer, assigns unique and mutually recognizable identification information as a file name, and stores it in an auxiliary storage device such as a hard disk. , The divided blocks are sequentially transferred, and the receiving terminal sequentially receives the transferred divided blocks, verifies the validity of each divided block, retransmits the divided blocks that were not received normally, and reconstructs the file. Are performed in parallel.

In the above embodiment, the size of the data included in the divided block is fixed. However, in order to cope with a wireless communication line having a large fluctuation in the communication line quality, there are cases where the transmission error exceeds a certain ratio. When retransmitting a divided block that has not been transmitted normally, the block length of the transfer unit may be made smaller.

In the above embodiment, the terminal device has both the file transmission control function 11 and the file reception control function 12, but may have only one of them.

In the above-described embodiment, the terminal device is realized by previously incorporating software for realizing the file transmission control function 11 and the file reception control function 12 into a personal computer or the like. By preparing a storage medium in which the above-mentioned software is read from this storage medium, an arbitrary computer can be made to function as a terminal device.

The calling process for line connection and the line disconnection process after the transfer completion notification response is sent and received may be performed by either the transmitting terminal or the receiving terminal.

In addition, various modifications can be made without departing from the spirit of the present invention.

[0088]

According to the present invention, the transmitting terminal divides the data of the transfer target file in order from the beginning for each predetermined amount, and indicates the position in the transfer file for each of the divided data. Predetermined location information;
A plurality of divided blocks are created by adding predetermined error check information enabling the presence / absence of a transmission error, and the plurality of divided blocks are all transmitted or the communication line is disconnected. Until the transmission of all the divided blocks has been completed, the communication line is disconnected in response to the completion of transmission of all of the divided blocks, the transmission of the divided blocks is temporarily stopped, and then the reception side terminal transmits the divided blocks. Is transmitted, the requested divided block is transmitted.

Further, the receiving terminal receives the divided block arriving via the communication line, checks whether or not there is a transmission error in the received divided block using the error check information. After the disconnection, the transmission side requests the transmission side terminal to transmit a divided block determined to be erroneous by the inspection or an unreceived divided block, and when the communication line is disconnected, all the divided blocks have no errors. If the transfer has been successful, the completion of the transfer is notified to the terminal on the transmitting side, and the divided blocks that have been received without errors are combined to reconstruct the transfer target file.

As a result, it is possible to efficiently transfer the data file while minimizing the increase in overhead when the communication line is disconnected.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a main configuration of a terminal device for realizing a file transfer system according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure of a control unit 1 in a file transmission process.

FIG. 3 is a diagram showing a division state of data to be inserted into a divided block from a data file (original file) and a reconstruction state of a reconstructed file from data inserted into the divided block.

FIG. 4 is a flowchart showing a processing procedure of the control unit 1 at the time of file reception processing.

FIG. 5 is a sequence diagram showing an example of a file transfer sequence in the case where there is no transmission error in a divided block and there is no line disconnection during transfer.

FIG. 6 is a sequence diagram showing an example of a file transfer sequence when there is a transmission error in a divided block and there is no line disconnection during transfer.

FIG. 7 is a sequence diagram showing an example of a file transfer sequence in the case where there is no transmission error in a divided block and there is a line disconnection during transfer.

FIG. 8 is a sequence diagram showing an example of a sequence in a case where a data file is temporarily reconstructed using only some of the divided blocks that can be normally received.

FIG. 9 is a diagram showing a state of rebuilding a data file in a case where the rebuilding of the data file is performed tentatively using only some of the divided blocks that can be normally received.

FIG. 10 is a sequence diagram showing an example of a sequence in which creation and transfer of a divided block are performed in parallel, and validity verification and reconstruction of a data file are performed in parallel with the operation of receiving the divided block.

FIG. 11 is a sequence diagram showing a modified example of a sequence for file transfer.

FIG. 12 is a sequence diagram showing a modification of the sequence for file transfer.

FIG. 13 is a diagram showing a configuration of a collaborative work system which is an example of an application target of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Control part 2 ... Storage part 3 ... Input part 4 ... Display part 5 ... Modulation / demodulation part 6 ... Network control part 11 ... File transmission control function 11a ... File division means 11b ... Division block transmission means 11c ... Line disconnection control means 11d ... Request transmission control means 12 File reception control function 12a Divided block reception means 12b Error checking means 12c Transmission request means 12d Transfer completion notification means 12e File restructuring means

Claims (6)

[Claims] In a file transfer method for performing a file transfer between two terminals connected to each other via a communication line, a terminal on a transmitting side transmits data of a transfer target file in a predetermined amount in order from the top. A plurality of data obtained by adding predetermined position information indicating the position in the transfer file and predetermined error check information enabling the presence or absence of a transmission error to be added to each of the divided data. A divided block is created, and the plurality of divided blocks are sequentially transmitted until all of the divided blocks are completed or the communication line is disconnected, and in response to completion of transmitting all of the divided blocks. Then, after the communication line is disconnected and the transmission of the divided block is temporarily stopped, if the transmission of the divided block is requested from the terminal on the receiving side, the requested division is performed. A lock is transmitted, and the receiving terminal receives the divided block arriving via the communication line, checks whether or not there is a transmission error in the received divided block using the error check information, After the line is disconnected, the transmission side requests the transmitting terminal to transmit a divided block determined to be erroneous by the check or a non-received divided block, and when the communication line is disconnected, all divided blocks are transmitted. If the transmission was completed without error, a notification to the effect that the transfer was completed is sent to the terminal on the transmission side, and the transfer target file is reconstructed by synthesizing the divided blocks that could be received without error. File transfer method to use. 2. The file transfer method according to claim 1, wherein the transmitting terminal reduces the size of the divided block to be transmitted in response to a request from the receiving terminal. 3. A file transfer system for transferring a file between two terminals connected to each other via a communication line. A plurality of data obtained by adding predetermined position information indicating the position in the transfer file and predetermined error check information enabling the presence or absence of a transmission error to be added to each of the divided data. File dividing means for creating a divided block; transmitting side line disconnection detecting means for detecting that the communication line has been disconnected; and transmission of all of the plurality of divided blocks created by the file dividing means is completed. Or the divided blocks that are sequentially transmitted until the transmission line disconnection detecting means detects that the communication line is disconnected. Transmission means; line disconnection means for disconnecting the communication line in response to completion of transmission of all of the divided blocks by the divided block transmission means; and a terminal on the receiving side after temporarily stopping transmission of the divided blocks. Requesting transmission of a divided block from a requesting block, and request transmission control means for causing the divided block transmitting means to transmit the requested divided block, and to a receiving terminal via the communication line. Divided block receiving means for receiving an incoming divided block, error checking means for checking the presence or absence of a transmission error in the divided block received by the divided block receiving means using the error check information, and disconnecting the communication line. Receiving line disconnection detecting means for detecting that the communication line has been disconnected, and detecting that the communication line has been disconnected by the receiving line disconnection detecting means. After that, the transmission request unit for requesting the transmitting terminal to transmit the divided block determined to be erroneous by the error checking unit or the unreceived divided block, and receiving the communication line being disconnected. If all the divided blocks have been received without error when detected by the side line disconnection detecting means, a transfer completion notifying means for notifying the transmitting terminal that the transfer has been completed; A file transfer system comprising: a file reconstructing unit that reconstructs the transfer target file by combining blocks. 4. The file transfer system according to claim 3, wherein said request transmission control means reduces the size of a divided block transmitted in response to a request from a terminal on the receiving side. 5. The data of the transfer target file is divided from the beginning in order of a predetermined amount, and each of the divided data has predetermined position information indicating a position in the transfer file, and presence or absence of a transmission error. And a file dividing unit that creates a plurality of divided blocks by adding predetermined error check information that allows the file to be inspected, and complete transmission of the plurality of divided blocks created by the file dividing unit. Or a divided block transmitting means for sequentially transmitting until the communication line is disconnected by a predetermined transmitting side line disconnection detecting means, and transmitting all of the divided blocks by the divided block transmitting means. Line disconnection control means for causing a predetermined line control unit to disconnect the communication line in response to the completion of the transmission, and If transmission of the divided block is requested from the receiving terminal after the suspension, operation as the respective means with the request transmission control means for causing the divided block transmitting means to transmit the requested divided block. Storage medium storing an operation program for causing a computer to perform the operation. 6. A divided block receiving means for receiving a divided block arriving via a communication line, and error check information included in the divided block, the presence or absence of a transmission error in the divided block received by the divided block receiving means. Error checking means for checking by using a predetermined block on the receiving side after the disconnection of the communication line is detected by the predetermined receiving line disconnection detecting means, Transmission request means for requesting the transmission side terminal to transmit the divided blocks, and all the divided blocks can be received without error when the reception line disconnection detection means detects that the communication line has been disconnected. Transfer completion notifying means for notifying the transmitting terminal that the transfer has been completed, and combining the divided blocks received without error with the transfer Storage medium storing an operation program for causing an operation as each means of the file reconstruction means for reconstructing an elephant file on the computer.