JP2004213508A - File download method and system using peer to peer technique - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To download a file over a tranfer rate of a server, and to download the file, even if it is difficult to receive data because of access concentration to the server, by receiving a file required by a client not only from the server but also from other PC on a network which retains a copy. <P>SOLUTION: On an information network NW capable of communicating one another, data is obtained not only from a server SV but also from a client C2, which retains a copy or a part of a required file, by peer to peer communication when a client C1 requires a file to the file server SV. Thus, the file can be downloaded at a higher speed. Besides, the file can be received from the client C2 even if it is difficult to download because network load is concentrated on the server SV. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for transferring a file between a server that provides information that is communicable with each other and is connected to a network and a client that requests the file.
[0002]
[Prior art]
When downloading a file from a server connected to a network to a client, a problem is to reduce the download time by eliminating bottlenecks such as congestion between the server and the network and communication speed between the network and the client. On the other hand, in the technology described in Patent Document 1, a member who has contracted with an Internet service provider (hereinafter abbreviated as ISP) connects a personal computer (hereinafter abbreviated as PC) to the ISP via a general public line, and By connecting to the ISP simultaneously from the PC via the digital mobile phone public line by the member's mobile phone and establishing a two-line connection between the ISP and the PC, the divided files are sent out in parallel and downloaded to the PC at high speed Is what you do.
[0003]
In addition, the technology described in Patent Document 2 arranges an information object storage device called an object pump near a client that is broader than a server, distributes a data request from the client on behalf of the server, and further transmits the data. By discriminating and caching, the efficiency of communication between the client and the server is improved.
[0004]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-215497 (FIG. 1, FIG. 6, etc.)
[0005]
[Patent Document 2] Japanese Patent Application Laid-Open No. 2001-184252 (FIGS. 2A to 2C and the like)
[0006]
[Problems to be solved by the invention]
However, in the technology described in Patent Literature 1, the communication path between the ISP and the PC is duplicated to improve the communication speed. Therefore, the mechanism in which data flows from the server to the client remains unchanged. It is not possible to cope with a decrease in transfer speed due to congestion in the server or concentration of access to the server. Further, the communication path is limited to only the handheld device, and the mobile phone public line is used in addition to the general public line, so that the communication cost becomes high.
[0007]
In the technique described in Patent Document 2, it is necessary to install an object pump as a dedicated device in advance, and the object pump can be regarded as a server on a network. There is.
[0008]
In addition, existing peer-to-peer communications on the Internet have a one-way data flow and do not serve as a complement to files.
[0009]
An object of the present invention is to obtain a file requested by a client not only from a server but also from another PC on a network holding a copy, so that the file can be downloaded at a speed exceeding the transfer speed of the server. Another object of the present invention is to provide a technique for downloading a file even when it is difficult to obtain data due to concentrated access to a server.
[0010]
[Means for Solving the Problems]
To achieve the above object, an invention according to claim 1 is a system in which a file server that provides a file and one or more clients that request the file are connected to a network, wherein the client downloads a desired file. Transmitting a file acquisition request from a first client to the file server; and transmitting the requested file to the first client from the file server that has received the file acquisition request. Starting transmission in block units obtained by dividing the file into a predetermined number, and determining whether there is a second client downloading the requested file in the file server that has received the file acquisition request. And there was the second client Instructing the first and second clients to send the block of the file that the second client has already obtained to the first client in peer-to-peer communication; Transmitting the block of the file from the second client to the first client in response to the request, and, in the first client, a block obtained from the file server and a block obtained from the second client And a step of composing a file in combination with the above.
[0011]
An invention according to claim 2 is a file download method in which a client downloads a desired file in a system in which a file server that provides a file and one or more clients that request the file are connected to a network. Transmitting a file acquisition request from the first client to the file server; and dividing the requested file into a predetermined number from the file server receiving the file acquisition request to the first client. Starting transmission in units; determining whether there is a plurality of second clients downloading the requested file in the file server receiving the file acquisition request; When there is a second client, Instructing the client and a plurality of second clients to send the block of the file that each of the second clients has already obtained to the first client in peer-to-peer communication; Transmitting the block of the file from each of the second clients to the first client in response to the instruction; and, in the first client, the block acquired from the file server and the plurality of second files. And constructing a file together with the blocks obtained from the client.
[0012]
The invention according to claim 3 is a file download method in which a client downloads a desired file in a system in which a file server that provides a file and one or more clients that request the file are connected to a network. Transmitting a file acquisition request from the first client to the file server; and, if the file server determines that data cannot be transmitted in response to the file acquisition request, Determining whether or not there is a client, and, when there is the second client, performing peer-to-peer communication with the first and second clients using the file already obtained by the second client. Instructs the first client to transmit A method, characterized by comprising a step of transmitting the file to the first client from the second client receives the instruction.
[0013]
The invention according to claim 4 is a file download method in which a client downloads a desired file in a system in which a file server that provides a file and one or more clients that request the file are connected to a network. Transmitting a file acquisition request from the first client to the file server; and, if the file server determines that data cannot be transmitted in response to the file acquisition request, the requested file is set to a predetermined number. Searching for a plurality of second clients having any of the divided blocks; and for each of the first clients and the plurality of searched second clients, each of the second clients Blocks the file that has already been Instructing transmission to the first client in two-peer communication; and transmitting the block of the file to the first client from each of the plurality of second clients in response to the instruction; And constructing a file by combining the blocks obtained from the plurality of second clients in the first client.
[0014]
According to a fifth aspect of the present invention, in the file download method according to the first or second aspect, the first client is transmitted in parallel with the data transmission from the second client to the first client by peer-to-peer communication. Transmitting the block of the file from the client to the second client.
[0015]
According to a sixth aspect of the present invention, in the file download method according to the first or fifth aspect, the blocks obtained by dividing the file are ordered in a predetermined order, and a block unit from the file server to the second client is provided. And the transmission in block units from the second client to the first client is performed in accordance with the order, and the transmission in block units from the file server to the first client and the transmission from the first client to the first client The transmission in units of blocks to the second client is performed in an order reverse to the above order.
[0016]
An invention according to claim 7 is a file download system in which a file server that provides a file and one or more clients that request the file are connected to a network, wherein the file server transmits the file from a first client. Means for receiving the requested file acquisition request, means for starting transmission to the first client which has transmitted the file acquisition request in units of blocks obtained by dividing the requested file into a predetermined number, and downloading the requested file. Means for determining whether or not there is a second client that is performing, and when there is the second client, the second client has already acquired the first and second clients. Indicating sending the block of the file to the first client in peer-to-peer communication And a means for transmitting a file acquisition request to the file server; and when the file server instructs the peer-to-peer communication, the first client connects to the instructed second client; Means for receiving a block of the file transmitted from a second client, and means for configuring a file by combining a block obtained from the file server and a block obtained from the second client, The client of claim 2, further comprising a unit that, when instructed by the file server to perform the peer-to-peer communication, connects to the designated first client and transmits the block of the file to the first client. And
[0017]
The invention according to claim 8 is a file download system in which a file server that provides a file and one or more clients that request the file are connected to a network, wherein the file server transmits the file from a first client. Means for receiving a requested file acquisition request, means for determining whether there is a second client having the requested file when it is determined that data cannot be transmitted in response to the file acquisition request, Means for instructing the first and second clients, when there is a client, to transmit the file already acquired by the second client to the first client by peer-to-peer communication. The first client sends a file acquisition request to the file server Means for connecting to the instructed second client when receiving the instruction of the peer-to-peer communication from the file server, and receiving the file transmitted from the second client. Wherein the client is connected to the instructed first client and transmits the file to the first client when the file server instructs the peer-to-peer communication.
[0018]
The invention according to claim 9 is a file server that supplies a file to one or more clients connected via a network, wherein the unit receives a file acquisition request transmitted from a first client, Means for determining whether a bandwidth for transmitting the requested file to the first client can be secured when receiving the file acquisition request; and, if the bandwidth can be secured, the requested file is reduced to a predetermined number. Means for starting transmission in divided block units, means for determining whether or not there is a second client downloading the requested file, and when there is the second client, the first and second In a second client, the block of the file already obtained by the second client is transmitted to the second client by peer-to-peer communication. Characterized in that it comprises means for instructing to send to the client.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
[0020]
FIG. 1 is an explanatory diagram showing the concept of a file download system using the peer-to-peer technology of the present embodiment. As shown in FIG. 1, a file server SV that provides a file to the public, and a client C1 and a client C2 that request download of the same file from the file server SV can communicate with each other via a communication network NW such as the Internet. Connected in a proper state. The server SV divides the file into logical information units called blocks, and transmits the data to the client C1 and the client C2 by dividing the data into data D1 and data D2 so that blocks do not overlap. The client C1 and the client C2 obtain address information of each other via the server SV and establish a connection. The client C1 stores the blocks transmitted from the server SV in itself, and transmits blocks not obtained by the client C2 to the client C2 (D4). Similarly, the client C2 transmits a block not obtained by the client C1 to the client C1 (D5).
[0021]
FIG. 2 is an explanatory diagram illustrating an example of a process in which a file is processed by a server or a client through a communication network. The server SV internally manages the file to be transmitted in units of blocks, and transmits the file to the client C1 and the client C2. For example, the file is transmitted from the first block to the client C2 in the order of blocking, and is transmitted to the client C1 in the reverse order from the end of the block. As a result, the block to be transmitted to the client C1 and the block to be transmitted to the client C2 are transmitted so as to avoid overlapping. FIG. 2 shows that blocks 1, 2, 3, and 4 are transmitted in this order from the server SV to the client C2, and that block 5 is currently being transmitted. Also, it is shown that blocks 10, 9, and 8 are transmitted in this order from the server SV to the client C1, and blocks 7 and 6 are currently being transmitted in this order.
[0022]
Upon completion of receiving one block, the client C1 saves the block in its own storage device, and immediately transmits the block to the client C2. Similarly, the client C2 transmits the reception block to the client C1. FIG. 2 shows the transmission of block 9 from client C1 to C2 and the transmission of blocks 3 and 4 from client C2 to C1. Each client combines all the blocks received from the server SV and the blocks received from the peer-to-peer connected partner and converts them into a target file.
[0023]
FIG. 2 shows a mode in which a target file is obtained by combining not only the peer-to-peer communication but also a block sent from the server SV and a block sent from another client in the peer-to-peer communication.
[0024]
FIG. 3 is an explanatory diagram illustrating a case where a client cannot connect to the server. The file server SV rejects the connection request (R1) of the client C1 exceeding the limit in order to secure a certain bandwidth when transferring a file to the client. Instead, the client C1 is instructed to acquire a file from the client C2 that has a copy of the requested file (F1) and is currently connected to the network NW (R2). However, an instruction is issued to start communication with the client C1 (R3). Thereafter, all the contents of the requested file F1 are transmitted from the client C2 to the client C1 (D8).
[0025]
FIG. 3 shows a mode in which a client obtains a target file from another client only by peer-to-peer communication.
[0026]
Next, the operation process of the present embodiment shown in FIGS. 1, 2 and 3 will be described using the flowchart of FIG. Upon receiving a file acquisition request from the client C1 existing on the network NW (S101), the file server SV acquires the address of the client C1 on the network and the requested file name (S102). At this time, the file server SV checks whether or not the file can be sent to the client C1 at a transfer rate higher than a certain reference by using the band check function (S103), and decides to send if there is enough band. , To S107. If there is not enough band, it is determined that the transmission from the file server SV is abandoned and only the file transfer between the peer-to-peer connections is performed, and the data transmission from the server SV is rejected (S104). However, it is checked whether there is another client having a copy of the same file on the network NW (S105), and if there is, the process proceeds to S110. If the target file does not exist in any client on the communicable network, the client C1 cannot obtain the file (S105, S106).
[0027]
If it is determined in S103 that data transmission from the file server SV is determined, it is checked from the stored client information whether another client connected to the same file as the file requested by the client C1 is downloading (see S103). S107). As a result, if the corresponding file is not being downloaded by another client, the file server SV transmits the file to the client C1 in order from the beginning of the block of the file, and receives when all the blocks are received by the client C1. Upon receiving the completion notification, the communication is terminated (S108). Thereafter, the information of the client C1 is deleted from the server SV (S109). However, if another client requests the file while the file is being received, the client C1 may be the target of a peer-to-peer communication pair. In that case, it plays the role of the client C2.
[0028]
As a result of the investigation (S107), if another client is in the process of downloading the file, a client that performs a peer-to-peer connection with the client C1 is selected. First, it is checked whether or not one client is downloading the file (S110). If there is one, the client is unconditionally determined as the client C2 to be paired (S110, S112). When there are a plurality of clients being downloaded, an address list of the corresponding client is transmitted to the client C1, and the client C1 is paired by a transfer speed test or a distance measurement between clients or a random selection based on the list. C2 is determined (S111, S112). Even when the data transmission from the server SV is rejected and the file transfer is only the peer-to-peer communication (when proceeding from S105 to S110), the client C2 to be paired is similarly determined.
[0029]
When the client C2 to be the peer-to-peer communication partner is determined, the file server SV notifies the client C2 of the address of the client C1 and instructs the client C2 to prepare for the peer-to-peer communication (S113). It instructs the client C1 to start the peer-to-peer communication by notifying the address of the client C2 (S114). The subsequent peer-to-peer communication is controlled between the clients according to the data flows D6 and D7 in FIG.
[0030]
Here, if the file transfer is not in the mode of only the peer-to-peer communication (that is, in the case of the mode of FIG. 2 instead of FIG. 3), the process proceeds from S115 to S116, and the data is transmitted from the file server SV to the client C1. Since the client C2 has already instructed the client C1 to transmit from the first block of the file by peer-to-peer communication in S113 and S114, the file server SV transmits the blocks in reverse order from the end of the file. This transmission is continued until a file reception completion notification is received from the client C1 (S116). When the notification is received, the information of the clients C1 and C2 is deleted (S117). If the file transfer is in the mode of only the peer-to-peer communication (that is, the mode of FIG. 3), the process proceeds from S115 to S117. Since the file transfer by the peer-to-peer communication has already been instructed in S113 and S114, there is no need to transmit data from the server SV.
[0031]
FIG. 5 is a flowchart showing a data transfer process between clients after the file server SV instructs the peer-to-peer connection in the processes S113 and S114 in FIG. When instructed to start the peer-to-peer connection in S113, the client C2 receives the address of the client C1 from the server SV and waits for a connection request from the client C1 (S201, S202). When the client C1 receives the address of the client C2 from the server SV in S114 and is instructed to start a peer-to-peer connection, the client C1 issues a connection request to the client C2 accordingly (S203, S204). When confirming this connection request, the client C2 instructs both clients to transfer data (S205).
[0032]
The file is transmitted to the client C1 in reverse order from the last block of the file with the file server SV as the transmission source (FIG. 2) or is not transmitted (FIG. 3). It is transmitted (S206). Conversely, since the file is transmitted from the file server SV to the client C2 in order from the head block of the file, the client C1 transmits the file in reverse order from the tail block of the file (S207). However, if the file existing in the client C2 is already the same as that on the file server SV, the transmission to the client C2 is not performed.
[0033]
FIG. 6 is a flowchart showing a file receiving process in the client. When the client requests the file server SV to acquire a file (S301), the server SV returns block information such as the block size of the target file and the total number of blocks, and downloads the file only from the server SV (S108 in FIG. 4). A mode is returned (S302) whether the server and the peer-to-peer communication are used together (FIG. 2), only the peer-to-peer communication is performed (FIG. 3), or the file cannot be acquired (S106 in FIG. 4). If the file can be obtained (S303), all the blocks are received (S304), assembled and filed (S305), and the server SV or the source of the peer-to-peer communication is notified of the completion of the file reception (S306). . If the file cannot be acquired (S303), the process ends.
[0034]
FIG. 7 is a flowchart showing the operation of a client having a copy of the same file as the server SV. It connects to the file server SV, registers its own address and information of the file it owns in the server, and waits for a client to be a peer-to-peer connection partner (S401). Thereafter, the peer-to-peer communication is started (S402), and when the exchange of the file is completed, the own information registered in the server SV is deleted (S403), so that the own information is registered again and the apparatus stands by (S401). Note that the loop termination condition until the registration with the server is stopped (S404) is that a certain period of time has elapsed since the client first acquired the file from the server SV, or the server SV recovered a file transfer speed higher than the reference. It is determined whether a certain time has elapsed since the start of the process.
[0035]
FIG. 8 is a table showing a table for managing connections with clients in the server SV. When the client connects to the server, the server is notified of the client's address, the requested file name, and, if the user already owns the file or a block that is a part, those information. The server SV stores such information in the management table of FIG. Records in this table are managed by assigning a unique management number to a single connection to a file or a connection between clients in a peer-to-peer connection. The mode column of the management table stores the type of download by the server alone, the combination of peer-to-peer and download from the server, or the download of peer-to-peer only. The status column stores the status of what kind of communication is currently being performed between the server and the client or between the clients. When the server receives a file download completion notification from each client, the corresponding connection information column is deleted.
[0036]
The server SV manages each client in such a table, and determines S107 and S104 in FIG. 7 based on this table. In S111 of FIG. 7, the information in this table is sent to the client to determine the peer of the peer-to-peer communication. Instead of having the client determine the peer-to-peer partner, the server SV may appropriately determine the partner client from the table in FIG.
[0037]
In the above embodiment, the case of two clients has been described. However, the download efficiency can be improved by executing parallel download and mutual complement for three or more clients. In this case, for example, the file to be downloaded can be divided into partial files corresponding to the number of clients on the server SV side, and each client can be downloaded from the first block of the divided partial file. Even in the case of three or more clients, the state of each client is managed by the server in a table similar to that shown in FIG. 8, so that which block should be transferred between which client and which client by peer-to-peer communication. Can all be managed by the server. Therefore, the server can issue necessary and sufficient instructions for peer-to-peer communication.
[0038]
【The invention's effect】
As described above, according to the present invention, not only the data transfer by the connection between the server and the client, but also the part that has not yet been obtained from the server is taken in parallel from another machine connected to the network. The information object can be obtained at higher speed. For this reason, there is no need to prepare devices on the network in advance.
[0039]
Further, by mutually complementing the file contents between the clients, not only the client that has requested the file later but also the client that was previously downloading alone has a higher transfer speed.
[0040]
Also, in managing the server that stores the files, it is possible to provide a constant transfer speed to the client by limiting the bandwidth, and it is possible to eliminate a bottleneck due to concentrated access to the server.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the concept of a file download system using a peer-to-peer technology according to an embodiment;
FIG. 2 is an explanatory diagram of an example showing a process in which a file is processed through a network.
FIG. 3 is an explanatory diagram showing a case where a client cannot be connected to a server;
FIG. 4 is a flowchart showing the flow of processing of a file server in the embodiment.
FIG. 5 is a flowchart of data transmission processing in a client during peer-to-peer communication.
FIG. 6 is a flowchart of a file receiving process in a client.
FIG. 7 is a flowchart showing the operation of a client having a copy of the same file as the server.
FIG. 8 is a diagram showing a table for managing connection with a client in a server.
[Explanation of symbols]
SV: file server, C1: client, C2: client, NW: communication network, F1: file, 1 to 10: block (unit of logically divided file).

Claims (9)

In a system in which a file server providing a file and one or more clients requesting the file are connected to a network, a file download method in which the client downloads a desired file,
Transmitting a file acquisition request from the first client to the file server;
Starting transmitting the requested file to the first client from the file server that has received the file acquisition request in units of blocks obtained by dividing the requested file into a predetermined number;
At the file server receiving the file acquisition request, determining whether there is a second client downloading the requested file;
Sending the block of the file already acquired by the second client to the first client in peer-to-peer communication to the first and second clients when the second client is present; Instructing
Transmitting the block of the file from the second client to the first client in response to the instruction;
A file download method comprising the steps of: forming a file by combining the block obtained from the file server and the block obtained from the second client in the first client. In a system in which a file server providing a file and one or more clients requesting the file are connected to a network, a file download method in which the client downloads a desired file,
Transmitting a file acquisition request from the first client to the file server;
Starting transmitting the requested file to the first client from the file server that has received the file acquisition request in units of blocks obtained by dividing the requested file into a predetermined number;
At the file server receiving the file acquisition request, determining whether there are a plurality of second clients downloading the requested file;
When there are the plurality of second clients, the block of the file that each of the second clients has already obtained is transmitted to the first client and the plurality of second clients by peer-to-peer communication. Instructing the first client to send;
Transmitting the block of the file from each of the second clients to the first client in response to the instruction;
A file download method, comprising the step of, at the first client, configuring a file by combining blocks obtained from the file server and blocks obtained from the plurality of second clients. In a system in which a file server providing a file and one or more clients requesting the file are connected to a network, a file download method in which the client downloads a desired file,
Transmitting a file acquisition request from the first client to the file server;
When the file server determines that data cannot be transmitted in response to the file acquisition request, determining whether there is a second client having the requested file;
Instructing the first and second clients to send the file already acquired by the second client to the first client in peer-to-peer communication when the second client is present Steps to
Receiving the instruction and transmitting the file from a second client to the first client. In a system in which a file server providing a file and one or more clients requesting the file are connected to a network, a file download method in which the client downloads a desired file,
Transmitting a file acquisition request from the first client to the file server;
When the file server determines that the data cannot be transmitted in response to the file acquisition request, a search is made for a plurality of second clients having any one of blocks obtained by dividing the requested file into a predetermined number. Steps and
For the first client and the plurality of searched second clients, transmitting the block of the file which each of the second clients has already obtained to the first client in peer-to-peer communication. Directing,
Transmitting the block of the file from each of the plurality of second clients to the first client in response to the instruction;
Configuring the file by combining the blocks obtained from the plurality of second clients in the first client. The file download method according to claim 1 or 2,
Transmitting a block of the file from the first client to the second client in parallel with transmitting data in a peer-to-peer communication from the second client to the first client. Method. The file download method according to claim 1 or 5,
The blocks obtained by dividing the file are ordered in a predetermined order, and the block unit transmission from the file server to the second client and the block unit transmission from the second client to the first client The transmission is performed in accordance with the order, and the transmission in block units from the file server to the first client and the transmission in block units from the first client to the second client are performed in reverse order to the order. File download method characterized by the following. A file download system in which a file server providing a file and one or more clients requesting the file are connected to a network,
The file server,
Means for receiving a file acquisition request sent from the first client;
Means for starting transmission to the first client that has transmitted the file acquisition request in units of blocks obtained by dividing the requested file into a predetermined number;
Means for determining whether there is a second client downloading the requested file;
Sending the block of the file already acquired by the second client to the first client in peer-to-peer communication to the first and second clients when the second client is present; Means for instructing
The first client is
Means for transmitting a file acquisition request to the file server;
Means for connecting to the indicated second client when receiving the instruction of the peer-to-peer communication from the file server, and receiving the file block transmitted from the second client;
Means for composing a file by combining blocks obtained from the file server and blocks obtained from the second client,
The second client is
A file download system for connecting to the instructed first client and transmitting the file block to the first client when the file server instructs the peer-to-peer communication; . A file download system in which a file server providing a file and one or more clients requesting the file are connected to a network,
The file server,
Means for receiving a file acquisition request sent from the first client;
Means for determining whether there is a second client having the requested file when it is determined that data cannot be transmitted in response to the file acquisition request;
Instructing the first and second clients to send the file already acquired by the second client to the first client in peer-to-peer communication when the second client is present Means to do,
The first client is
Means for transmitting a file acquisition request to the file server;
Means for connecting to the instructed second client when receiving the instruction of the peer-to-peer communication from the file server and receiving the file transmitted from the second client,
The second client is
A file download system, comprising: means for connecting to the instructed first client and transmitting the file to the first client when the file server instructs the peer-to-peer communication. A file server for supplying a file to one or more clients connected via a network,
Means for receiving a file acquisition request sent from the first client;
Means for determining, when receiving the file acquisition request, whether or not a band for transmitting the requested file to the first client can be secured;
Means for starting transmission in units of blocks obtained by dividing the requested file into predetermined numbers if the bandwidth can be secured;
Means for determining whether there is a second client downloading the requested file;
Sending the block of the file already acquired by the second client to the first client in peer-to-peer communication to the first and second clients when the second client is present; Means for instructing the file server.

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