JPH09270790A - File distribution method and communication controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability and distribution efficiency of a distributed file at the time of distributing the file from a server terminal to plural client terminals. SOLUTION: The server terminal 10 divides a distribution object file into plural blocks and simultaneously transmits them to the plural client terminals 20a-20n. The client terminals 20a... store the respective blocks in a prescribed order, construct at least a part of the file and write the constructed part of the file in a memory for storing the file asynchronously with the block storage. Also, the sequence of the already received blocks is discriminated, the presence/ absence of non-received blocks are judged, and in the case that the non-received block is present, a retransmission request is transmitted to the server terminal 10. The server terminal 10 judges whether it is simultaneous retransmission or individual retransmission based on the number of the retransmission requests and the contents of the retransmission request and retransmits the non-received block by a unit corresponding to a judged result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, TCP / I.
The present invention relates to a file delivery technique in a client / server system in which a network is constructed using the P protocol.

[0002]

2. Description of the Related Art In a client / server system in which a plurality of client terminals are connected to one server terminal, when a file is distributed from the server terminal to each client terminal using the TCP / IP protocol, the conventional method has been used. Has adopted the following two methods.
The first method is an individual distribution method, in which files are individually distributed from the server terminal to each client terminal. In this method, it is necessary to issue as many files to be distributed (distribution target files) as the number of client terminals. On the other hand, the second method is a broadcast method, and unlike the individual distribution method, the server terminal simultaneously distributes one file to an unspecified number of client terminals.

In both types, the file to be distributed may be divided into blocks of a predetermined length on the server terminal side and distributed to the client terminal in block units. When the amount of work at the server terminal in this case is evaluated by the number of messages, in the case of the individual distribution method, the size of the distribution target file / 1 block length x the number of client terminals, and in the case of the broadcasting method, the size of the distribution target file / 1 block Since the length is long, if the size of the file to be distributed in both systems is equal to the one block length, the broadcast system obviously requires less load on the system. Therefore, if this broadcast method is adopted, there is an advantage that the load on the communication path such as a LAN (regional network) can be reduced and the work efficiency can be improved.

[0004]

However, when the broadcast method is adopted, the transmission block from the server terminal may not always be correctly received by the client terminal depending on the processing capacity of the client terminal and the state of the communication path. There was a problem. For example, in each client terminal, if the buffer memory (message buffer, etc.) for storing the received block does not have sufficient capacity to store the subsequent block length, or if the received block is stored or the stored block is stored, If the delivered subsequent block arrives earlier than the processing, reception of the subsequent block fails and block omission occurs. Conventionally, the compensation method for such a block omission has not been sufficient, so that the reliability of the delivered file cannot be improved.

Further, in the case of the broadcast system, the server terminal cannot grasp which client terminal is currently in what kind of reception condition, and therefore cannot properly judge the timing of the next file distribution. There was also a problem that the delivery efficiency could not be improved.

An object of the present invention is to enhance the reliability of a received file at each client terminal and to enable efficient distribution when a file is distributed from a server terminal to a plurality of client terminals by a broadcast method. To provide a file delivery method. Another object of the present invention is to provide a communication control device suitable for implementing the above file distribution method.

[0007]

According to a file distribution method provided by the present invention, a file to be distributed is divided into a plurality of blocks and each block is simultaneously transmitted from a file transmission terminal to a plurality of file reception terminals together with division order information. And a step in which each file receiving terminal that receives the block stores each block in an order determined by the division order information to construct at least a part of the file to be distributed, and the storage of the block is asynchronous. To write the construction part of the file to be distributed in the file storage memory, to determine the order of the received blocks to determine whether there is an unreceived block in a predetermined period, and when there is an unreceived block, Transmitting a resend request for an unreceived block to the file sending terminal, and the resending File transmission terminal, which has received the required is,
Retransmission processing according to the number of retransmission requests and the content of the retransmission request,
For example, the step of determining at least one of the retransmission destination and the number of retransmission blocks is included.

The step of determining the presence / absence of an unreceived block in the file receiving terminal is, for example, when the division order information of a subsequent receiving block following one receiving block is not an expected value, the expectation until the corresponding block is received. A process of holding division order information corresponding to a value is included.

The first communication control device provided by the present invention is a device that functions as a file transmission terminal that performs two-way communication with a plurality of file reception terminals, and distributes files to be distributed into a plurality of blocks. And a means for associating each division order information with each block, and a transmission means for simultaneously or individually transmitting the divided blocks to each file receiving terminal together with the division order information,
When a resending request is received from at least one file receiving terminal, a block specifying unit that specifies a block corresponding to the resending request based on the division order information, and the number of blocks specified by the block specifying unit or the resending Compare the judgment information including the number of requests with a predetermined reference value,
Means for performing a retransmission process according to the comparison result.

Further, the second communication control device provided by the present invention is a device for dividing a file to be distributed into a plurality of blocks and a means for associating each block with division order information. A device functioning as a file receiving terminal for bidirectional communication, comprising a file storage memory for storing the distribution target file, a plurality of buffer memories for accumulating the blocks, and receiving from the file transmitting terminal. While accumulating a plurality of blocks in the buffer memory in a predetermined order to construct at least a part of the distribution target file,
Memory control means for storing a construction part of the distribution target file accumulated in one buffer memory in the file storing memory asynchronously with accumulation of the block; division order information received together with a plurality of blocks from the file transmitting terminal; Receiving block monitoring means for comparing unreceived blocks with detected already received blocks, and, when this receiving block monitoring means detects unreceived blocks, sends a resend request for the unreceived blocks to the file transmitting terminal. And transmitting means.

The memory control means, for example, after the number of blocks stored in one buffer memory reaches a predetermined amount, stores the subsequent reception block in another buffer memory and also stores it in the one buffer memory. The receiving block monitoring means monitors, for example, division order information of individual receiving blocks to transfer the construction part of the distributed file to be transferred to the file storing memory, and one receiving block. When the division order information of the subsequent reception block following is not the expected value, the division order information corresponding to the expected value is held until the corresponding block is received.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The file distribution method of the present invention will now be described with reference to a client / client system using a TCP / IP protocol.
One embodiment when applied to a server type system will be described in detail.

FIG. 1 is a system configuration diagram according to this embodiment, and includes a server terminal 10 which is a first communication control device,
A plurality of client terminals 20 that are second communication control devices
a-20n are connected via a communication path 30 such as a LAN. In connection with the present invention, the file transmission terminal is the server terminal 10 and the file reception terminal is the client terminal 2.
It corresponds to 0a to 20n. The server terminal 10 has a file management unit 12, a header management unit 13, a block editing unit 14, a distribution control unit 15, a transmission processing unit 16, a reception processing unit 17, and a reception information analysis unit 18 according to a predetermined control program.
Function is realized.

The file management unit 12 extracts a file to be distributed from the file storage memory 11, divides the extracted file into a plurality of blocks having a length that does not cause fragmentation at the time of broadcasting, and provides division order information. To generate. The division order information is information including a division source file name and a division order number. This division order information is sent to the header management unit 13, where it is associated with each block. File management unit 12
Also performs retransmission control after file distribution based on the analysis result sent from the reception information analysis unit 18 described later. Specifically, the unreceived block corresponding to the retransmission request is specified by referring to the division order information of the individual blocks managed by the header management unit 13, and the total number of unreceived blocks or the number of retransmission requests is determined. When the value exceeds the reference value, for example, when it exceeds 20% of all blocks, control information for performing simultaneous retransmission of each file by the broadcast method is generated toward all the client terminals 20a to 20n. When the retransmission request is biased to a specific client terminal or concentrated on a specific block, control information for performing individual retransmission, broadcast retransmission for each file, or broadcast retransmission for each block is generated. Each control information is sent to the delivery control unit 15.

The block editing unit 14 edits each block and division order information to generate transmission information (including retransmission information) in a format according to the TCP / IP protocol. The distribution control unit 15 controls the distribution system of the transmission information or the retransmission information in the transmission processing unit 16 based on the control information sent from the file management unit 12. The reception processing unit 17 receives the reception information transmitted by each of the client terminals 20a to 20n after the file distribution, and the reception information analysis unit 18 analyzes the content of the resend request included in the reception information and then the file management unit. 12 is to be transmitted.

FIG. 2 is a block diagram of the client terminal according to the present embodiment. For convenience, the first client terminal 20 is shown.
Only a is shown. Other client terminal 20
b to 20n also have substantially the same configuration.

The client terminal 20a has a reception processing unit 21, a reception block monitoring unit 22, a memory control unit 23, and a serial number management table 2 according to a predetermined control program.
4, the buffer memory (message memory) 25, the file storage memory 26, the resend request information generation unit 27, and the transmission processing unit 28 are realized. Memory control unit 23
Is a table control unit 231 that writes and erases the serial number table 24, a buffer control unit 232 that performs block accumulation in the buffer memory 25, switching control of the writing surface, and the like, and writing to the file storage memory 26. Write control unit 2 for controlling
And 33.

The reception processing section 21 receives the division order information of the block and header sections from the server terminal and sends each reception information to the memory control section 23. Memory control unit 23
The operation of will be described later. Reception block monitoring unit 22
Monitors the presence or absence of an unreceived block for each file based on the division order information from the reception processing unit 21, and when an unreceived block is detected, the retransmission request information generation unit 27
Notify.

The serial number management table 24 holds an unreceived block as a “missing number” under the control of the table controller 231. Various methods can be adopted for identifying the unreceived block using the serial number management table 24. For example, all division order information is written in the serial number management table 24 at the time of simultaneous delivery from the server terminals 10, and the division order information of the corresponding block is erased each time a block is received. The remaining division order information becomes a missing number indicating an unreceived block. Alternatively, at the time of storage in the buffer memory 25, it is determined whether or not the division order information is an expected value, and the division order information of blocks that are not the expected value is sequentially recorded as a missing number. When the corresponding block is received later, the corresponding missing number is erased. In the present embodiment, the latter method is adopted for convenience. FIG. 3 is an explanatory diagram showing an example of the contents of the serial number management table 24.

The buffer memory 25 is a buffer controller 2
It has at least two recording surfaces that can be selectively switched by 32, and sequentially stores received blocks on the selected recording surface to reconstruct the file distributed from the server terminal 10. The file storage memory 26 is for storing the file construction part accumulated in the buffer memory 25.

Next, the specific operation of the client / server type system having the above-mentioned configuration will be described with reference to FIGS. FIG. 4 is a procedure explanatory diagram showing the primary transmission process in the server terminal 10, that is, the simultaneous distribution process by the broadcast method. The server terminal 10 first extracts a distribution target file from the file storage memory 11 (S10).
1). Then, the extracted file is sequentially divided into blocks of 1024 bytes, for example, and division order information is generated (S102). Division order information, that is, a file name and a number indicating the division order are added to the header of each block (S503), and all client terminals 20a to 20n are added.
Broadcast to all of you by broadcasting (S1
04). Steps S101 to S104 are repeated until all blocks of the file are completed (S1
05), and steps S101 to S105 are repeated until there are no more distribution target files (S106). After the primary transmission process, the retransmission process is performed as necessary according to the procedure shown in FIG.

In the resend process, first, when a resend request is received from at least one client terminal (S20).
1: Yes). It is determined whether or not batch retransmission is necessary (S20
2). As the determination criterion, the number of client terminals that have transmitted the retransmission request as described above is a reference value (for example, 20
%), And if the number of unreceived blocks is larger than a reference value (for example, 20% of the total), batch retransmission is performed (S2
03), otherwise, individual retransmission is performed (S204). The reference value can be arbitrarily set according to the type of file to be distributed and the number of client terminals.

Next, one procedure of the block accumulation process in the client terminal 20a will be described with reference to FIG. The client terminal 20a receives the distribution target file sent from the server terminal 10 for each block (S30).
1) Read the file name and division order number from the header of the received block (S302). Serial number management table 2
4, it is checked whether or not the division sequence number of the received block exists as a missing number (S303). If it exists, the missing number is deleted from the serial number management table 24, and the received block is stored in the buffer memory 25 (S307). S
When it is determined that there is no missing number in 303 (S303:
No) determines whether or not this number is the expected serial number (S3).
05). The "expected serial number" is, for example, "when the division sequence number of the immediately preceding reception block belonging to the same file is" 5 ".
6 "is applicable.

If the missing number does not exist in the serial number management table 24 and is not the expected serial number (S305: No), this is written in the serial number management table 24 as the missing number (S305).
306), the received block is stored in the buffer memory 25 (S307). In case of expected serial number (S305: Ye
s), immediately stores the received block in the buffer memory 25. In addition, here, for convenience, when a missing number occurs,
Although the case where this is written in the serial number management table 24 has been described, as described above, when the first block is received, the division order information of all subsequent blocks is written in the serial number management table 24, and individual blocks are received. It may be a method of sequentially erasing each time.

The above processing is repeated for other blocks of the file (S308: No), and when it is determined that the reception of all blocks is completed (S308: Yes), the serial number management table 24 is referred to (S309), It is determined whether there is a missing number left for the file (S31).
0). When the missing number is left (S310: Yes),
It is read and re-transmission request information is generated (S311),
A resend request is sent to the server terminal 10 (S31
2). After that, if it is retransmitted from the server terminal 10, S
The processing from 301 is performed again. If it is determined that there is no missing number in S310 (S310: No), the process ends.

As described above, even when the reception of some blocks constituting the distributed file fails, the block corresponding to the missing number is specified and the server terminal 10 is promptly retransmitted. Therefore, it is possible to reliably prevent omission of blocks when they are simultaneously delivered, and it is possible to improve the reliability of received files.

Next, the file writing process that is performed asynchronously with the block accumulation process in the client terminal 20a will be described with reference to FIG. The buffer control unit 232 selects the recording surface of the buffer memory 25, for example, the first surface,
The received block is stored in the corresponding position on the first surface, that is, the position indicated by the division order information (S401). This is associated with the block accumulation process described above. Check the remaining capacity of the first surface (S
402), if it is not full (S402: No), it is determined whether or not there is a subsequent block (S403), and if there is a subsequent block (S403: Yes), accumulation on the first surface is repeated. If the first surface is full (S402: Yes) and there is a subsequent block (S404: Yes), the buffer control unit 232 switches the recording surface to the second surface and stores the subsequent block at the corresponding position (S405). ). After the start of accumulation of the second surface, or when it is determined in S403 and S404 that there is no subsequent block, the write control unit 233 determines that the first
The block (constructed portion of the file) accumulated on the surface is stored in the file storage memory 26 (S40
6), the first surface is cleared in preparation for the next block accumulation (S407). In this way, the block accumulation process and the file writing process are performed at mutually independent timings, so at least block omissions caused by the file writing process can be prevented and the efficiency of use of the buffer memory 25 is maximized. be able to.

In the client-server system described above, FIG. 8 shows a retransmission mode after the server terminal 10 broadcasts a plurality of blocks by the broadcast method.
(A), (b) and (c) show.

In FIG. 8A, the first client terminal A sends a resend request indicating that the missing number is "21", that is, the 21st block of the file has not been received, and the second client terminal B Shows an example of a case in which a retransmission request for the missing number “82” is transmitted. In this case, since the number of retransmission blocks is small, only the block “21” corresponding to the first client terminal A and only the block “82” corresponding to the second client terminal B are individually retransmitted. on the other hand,
FIG. 8B shows an example in which the client terminals A, B, ... N request retransmissions in a number exceeding the reference value. In this case, the file is simultaneously retransmitted to all client terminals by the broadcast method. FIG. 8C is an example of the combination of the above examples. Broadcasting is performed only for client terminals with a large number of unreceived blocks,
Individual retransmission is performed to the client terminal with few unreceived blocks.

As described above, the client of the present embodiment
In the server type system, the risk of adopting the broadcast method, that is, there is no guarantee of the order of the messages,
Since we have devised a way to avoid efficient recovery in the event of a message dropout, etc., we can adopt the broadcast method in a safe environment, while reducing the load on the server terminal and communication path, The efficiency of file distribution can be improved. Further, since the processing of the present embodiment can be automated, there is an advantage that a plurality of remote client terminals can be centrally maintained.
It should be noted that the above is a description of the case where the present invention is applied to a client / server type system, but the present invention is similarly applied to a system including a file transmitting terminal and a file receiving terminal that can adopt a broadcast method. It goes without saying that you can do it.

[0031]

As is apparent from the above description, according to the present invention, since the order of the electronic messages is thoroughly compensated for when the missing of the electronic message occurs, the file is transmitted from the file transmitting terminal to the file receiving terminal. It is possible to improve the reliability when distributed by the broadcast method. As a result, the load on the communication path is reduced and the hardware resources can be effectively used.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a client / server type system according to an embodiment of the present invention.

FIG. 2 is a block configuration diagram of a client terminal according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an example of the contents of a serial number management table.

FIG. 4 is an explanatory diagram of a procedure of file distribution processing by the server terminal.

FIG. 5 is an explanatory diagram of a retransmission procedure by the server terminal.

FIG. 6 is an explanatory diagram of a procedure of a reception process by the client terminal.

FIG. 7 is an explanatory diagram of a file writing procedure by the client terminal.

FIG. 8 is an explanatory diagram of a retransmission mode according to the present embodiment, (a)
Shows an individual retransmission example, (b) shows a simultaneous retransmission example, and (c) shows a combination example thereof.

[Explanation of symbols]

 10 server terminal 11 file storage memory of server terminal 12 file management unit 13 header management unit 14 block editing unit 15 distribution control unit 16 transmission processing unit of server terminal 17 reception processing unit of server terminal 18 reception information analysis unit 20a to 20n client terminal 21 reception processing unit of client terminal 22 reception block monitoring unit 23 memory control unit 231 table control unit 232 buffer control unit 233 writing control unit 24 serial number management table 25 buffer memory 26 file storage memory of client terminal 27 retransmission request information generation unit 28 Transmission processing unit of client terminal 30 Communication path

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 1, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

[Fig. 2] ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 25, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Patent application title: File distribution method and communication control device

Claims (6)

[Claims] 1. A step of dividing a file to be distributed into a plurality of blocks and simultaneously transmitting each block together with the division order information from a file transmitting terminal to a plurality of file receiving terminals, and individual file receiving terminals receiving the blocks. A step of accumulating each block in the order determined by the division order information to construct at least a part of the distribution target file; and a construction part of the distribution target file in a file storage memory asynchronously with the accumulation of the block. A step of writing, a step of determining the order of the received blocks to determine the presence or absence of an unreceived block in a predetermined period, and a resend request for the unreceived block to the file transmission terminal when there is an unreceived block And the file transmitting terminal receiving the resend request determines the number of resend requests. File delivery method characterized by having the steps of performing a retransmission process according to the contents of the retransmission request. 2. The step of determining the presence or absence of an unreceived block in the file receiving terminal, when the division order information of a subsequent receiving block following one receiving block is not an expected value, the expected value is received until the corresponding block is received. 2. The file distribution method according to claim 1, further comprising a step of holding division order information corresponding to. 3. A device for bidirectional communication with a plurality of file receiving terminals, which divides a file to be distributed into a plurality of blocks and associates each block with division order information, the division. Transmitting means for simultaneously or individually transmitting the generated blocks together with the division order information to each file receiving terminal; and, when receiving a retransmission request from at least one file receiving terminal, divides the block corresponding to the retransmission request into the division order. The block specifying means specified based on the information is compared with the judgment information including the number of blocks specified by the block specifying means or the number of retransmission requests and a predetermined reference value, and the retransmission processing is performed according to the comparison result. A communication control device comprising means. 4. A device for performing bidirectional communication with a file transmission terminal, which comprises a unit for dividing a file to be distributed into a plurality of blocks and associating each block with division order information. A file storage memory for storing a file, a plurality of buffer memories for accumulating the blocks, a plurality of blocks received from the file transmission terminal are accumulated in the buffer memory in a predetermined order, and the distribution target file is stored. A memory control unit for building at least a part of the file storage memory in the file storage memory asynchronously with the storage of the block, and a plurality of units from the file transmission terminal. The division order information received with the block of Communication block detection means for detecting a lock, and transmission means for transmitting a resend request for the unreceived block to the file transmission terminal when the received block monitoring means detects the unreceived block. Control device. 5. The memory control means, after the number of blocks accumulated in one buffer memory reaches a predetermined amount, accumulates a subsequent reception block in another buffer memory and also accumulates it in the one buffer memory. 5. The communication control device according to claim 4, wherein the constructed part of the distributed file to be distributed is transferred to the file storage memory. 6. The reception block monitoring means monitors the division order information of each reception block, and when the division order information of a subsequent reception block following one reception block is not an expected value, until the corresponding block is received. The communication control device according to claim 5, which holds division order information corresponding to the expected value.