KR20030014094A - a method of collaborating in transferring a file in a networking environment - Google Patents

Abstract

PURPOSE: A method for commonly transmitting file at network environment is provided to receive a file from several severs after dividing the file at network environment. CONSTITUTION: A user receives a file list from a file managing server(S501) and designates a desired file to the file managing server(S502). The file managing server checks devices having the desired file, sorts the devices, and transmits the device to a user terminal(S503). The user terminal determines desired server to receive the file(S504). The user terminal informs the desired server about file segment information(S505). After the transmission is terminated, the user terminal composes the segments into one file(S507) and informs the termination of the transmission to the file managing system(S508).

Description

{A method of collaborating in transferring a file in a networking environment}

In the client / server model of a conventional network environment, a client uses a so-called 1: 1 transmission method in which a client connects to a server and receives a file. In this method, if the transmission speed of the server is low, the client should receive the file at a slow speed without fully utilizing its bandwidth. Even if the optimal server is connected, if the number of Internet users increases during the transmission, the transmission speed will drop significantly. There is a problem. In addition, when a file transfer server fails, the file transfer fails, so that the client needs to receive the file again from another server. In order to improve file transfer speed, US Patent No. 6,085, 251 discloses a method of transferring files in parallel. In this method, the server divides a file into multiple packets, transmits them to the client in parallel and simultaneously, and receives a packet reception signal at the same time. Make it a file. This method has a much faster file transfer rate than sending packets one by one and checking whether they are received. However, if there is a server failure, file transfer is not possible, so it does not guarantee stable file transfer.

The 1: 1 transmission method has such a limitation, and furthermore, in an environment in which the personal computer can act as a server due to the performance improvement of the personal computer, it is not necessary to adhere to the 1: 1 transmission method.

The present invention has been made in view of the above, and aims to improve transmission speed by allowing users to utilize bandwidth as much as possible by receiving one file from multiple servers instead of 1: 1 transmission.

In addition, the present invention aims to reliably transfer a file in a fault-tolerant manner by replacing it with another server when a problem occurs in one server among several servers during transmission. .

In addition, an object of the present invention is to provide a method for ensuring that multiple servers transmit pieces of the same file as a prerequisite for being able to receive one file from multiple servers.

In addition, the present invention provides a method for distributing and storing this file in multiple devices if the entire file cannot be stored in one device, and for viewing the entire contents of the file by the file transfer method according to the present invention. For the purpose of

The present invention relates to a file co-transmission method, and more particularly, to a method of receiving a single file from multiple servers in a network environment.

1 is an overall configuration diagram of a file transfer system according to the present invention.

2-4 is a block diagram of a file management system according to the present invention.

Fig. 5 is a flowchart showing the overall file transfer process according to the present invention.

6 is a data structure of a candidate server list storing information of servers capable of transferring files.

7 is an exemplary diagram of a log file for recording file transfer information.

8 is a view showing a state of transmitting a file according to the present invention.

9 is a diagram illustrating a file transfer from one device to several devices according to the present invention.

In order to achieve the above object, a first aspect of the present invention provides a method for transferring a file between devices connected through a network, the method comprising: selecting a file to be transmitted by a user device; and a device storing the file. Receiving information about the file information from a file management system managing file transfer, determining one or more servers to which the file is to be transmitted among devices storing the file, and transmitting the file to the one or more servers, respectively. Requesting to transmit a portion of the file; receiving portions of the requested file from each of the one or more servers; and merging portions of the transmitted file into one file. It is done.

Here, the server refers to a device that acts as a server, that is, a device for transmitting a file, and the transmission includes streaming as well as a download.

In order to receive a file from multiple servers, a system that manages file transfer must exist. Such a file management system may exist as a separate file management server or may be distributed among multiple devices.

When the user device determines one or more servers to transmit a file, it is desirable to determine the transmission speed in order of high. In addition, when receiving a part of a file from each of several servers, it is preferable to receive a large amount from a server having a high transfer rate and a small amount from a server having a low transfer rate.

After the user device receives parts of each file from multiple servers, it writes this information to a log file, which is then used to merge parts of the file into a single file.

The user device evaluates the transmission speed of the server every time a certain size packet is received from each server, and replaces the server with another server when there is a server that is seriously slowed or unstable.

The alternate server determines from the list of devices storing the file, received from the file management system, or requests the list from the file management system again, and determines from the updated list.

On the other hand, in order to divide and transmit a single file by multiple servers, it is necessary to ensure that the servers are all sending pieces of the same file. In the present invention, when the file is transmitted, the information of the original file is recorded in the metafile, When you send a file fragment to a user, you use a method that compares the file to be sent with the information stored in the metafile.

According to the first aspect of the present invention, by transmitting a single file from a plurality of servers divided by the user to maximize the bandwidth, it is possible to improve the transmission speed, to the server of one of the multiple servers during the transmission In the event of a problem, you can transfer the file to another server, allowing you to send files reliably, fault-tolerant.

The present invention can be used not only when a complete file is divided and transmitted from several servers, but also when a file is actually divided and stored in several places.

That is, a second aspect of the present invention provides a method for calling a file when a file is distributed and stored in a plurality of devices connected through a network, the devices storing each part constituting the file. Receiving information about a file management system from a file management system managing file transfer, determining, for each part of the file, one or more servers to which the part is to be transferred among the devices storing the part; Distributing and receiving each part of the file from each of the determined one or more servers for each part of the file, and merging each part of the transmitted file into one file.

Further, a third aspect of the present invention is a method for transferring a file from one device to a plurality of devices in devices connected via a network, wherein the one device is the fastest of the plurality of devices. Transmitting the file, and the fastest device receiving the file transfers the file back to the second fastest device among the plurality of devices, and the second fastest device receiving the file transfers the file to the third fastest device. Transmitting the received file to the slowest device, and when the one device completes the file transfer to one of the plurality of devices, the plurality of devices. It is characterized in that the transfer of the file back to another device.

Further, a fourth aspect of the present invention is a method for transferring a file from one device to a plurality of devices in devices connected via a network, wherein the one device transmits the file to the plurality of devices. And when the transmission amount exceeds a predetermined reference during the transmission, transmit the file only to the fastest device of the one of the plurality of devices, and the fastest device receives the file from the one device and simultaneously Transmitting the file to other ones of the plurality of devices.

According to the third and fourth aspects of the present invention, it is possible to transfer files from one device to multiple devices at high speed.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 shows the overall configuration of a file transfer system according to the present invention. As shown in FIG. 1, the file transfer system according to the present invention includes a plurality of devices 20 ₁ , 20 ₂ , 20 ₃ ,.. 20 _n connected through a network 10.

The network 10 includes a wired Internet using a modem, a PSTN, a dedicated line, and an ISDN, a wireless Internet through a cellular, PCS, microwave or satellite network, a local area network, an intranet, an extranet. Including all possible networking environments. Device (20_One, 20₂, 20₃, .. 20_n) Data such as PC, workstation, mini computer, mainframe computer, notebook computer, general portable communication terminal, PDA (personal digital assistant), settop box, digital television, web phone, etc. Any device that can communicate is available.

The devices 20 ₁ , 20 ₂ , 20 ₃ , .. 20 _n may receive files from or transfer files to other devices connected to the network 10. There is a file management system 30 to manage.

The file management system assigns a unique file ID to a file that is common to multiple devices, and manages a list of files that can be transferred between devices so that one device can divide and receive files from multiple devices. As shown in FIG. 1, one of the various devices shown in FIG. 1 may be a file management system, or several devices may cooperate with each other to form a file management system.

Several types of file management systems are shown in FIGS.

2 shows a centrally managed file management system 30, which implements the file management system in a large apparatus such as a server. In this case, the file management server manages all the information required for file transfer, and collectively controls file transfer between devices.

3 shows a distributed file management system 30 in which the file management system is distributed to various devices. In this case, the information necessary for the joint transmission of the file is distributed and stored in each device, and the control of the file transfer is performed by several devices in cooperation.

4 shows a hybrid file management system 30, which combines the systems of FIGS. In this case, information management and file transfer control necessary for file transfer are mainly performed in the file management system 30, but the rest of the devices share some work as well.

2 to 4 are merely examples of a file management system, and may be implemented in various topologies.

5 is a flowchart illustrating a process of file transfer according to the present invention.

First, the user device 20 to receive a file receives a list of files that can be received from the file management system 30 (S501), and designates a file to be transferred to the file management system 30. Inform (S502).

The file management system 30 identifies the devices storing the file designated by the user device 20, calculates the location and transmission speed of each device, and arranges the devices in the order of the highest transmission speed. 20) (S503). An example of such a device list (hereinafter referred to as "candidate server list" and "server" means a device acting as a server) is shown in FIG. As shown in Fig. 6, the candidate server list includes a server ID 601, a server position 602, and a server transmission speed 603 for each server, and are sorted from the server transmission speed is high. . The transmission rate 603 of the server is calculated in consideration of the bandwidth and the number of tasks currently being performed.

The user device 20 receives the candidate server list and determines servers suitable for receiving a file therefrom (S504). That is, the user device 20 designates n servers 40 starting from the fastest device so as to make the best use of its bandwidth.

BW v ₁ + v ₂ + Λ + v _n (v _i ≥v _{i + 1} )

BW: user bandwidth

v _i : Speed of the i device

As shown in the above formula, in order for the user device 20 to make full use of the bandwidth, the transmission speed of the server 40 should be added to a value close to the bandwidth, and in order to fully use the bandwidth, the transmission speed of the server 40 It is preferable that the sum of the sum is greater than or equal to the bandwidth. For example, in a slow transmission environment such as a modem user, only one server 40 having the fastest transmission speed may be specified.

After the user device 20 determines the n servers 40 having high transmission speeds, the user device 20 determines which parts are to be transmitted to which size from the determined servers 40 (S504). In this case, it is preferable to receive a large amount of the file from the server 40 having a high transmission speed, and to transmit a small amount of the file from the server 40 having a relatively low transmission speed.

f _i : Size of file fragment allocated by the i th device

F: File size to be transferred

The list of the transmission server 40 determined in step S504 and the information about the file fragments to be transmitted by each server 40 are recorded in a log file. This log file is needed later when the user device 20 receives file fragments from several servers 40 and merges them into one.

Next, the user device 20 requests a file transfer while notifying the determined transmission server 40 of information on the file fragment to be transmitted (S505).

The user device 20 receives the file fragment and records the received information in a log file. In this process, the server 40 having a problem in file transfer is transferred to another server 40 again. The file transfer will be described later in detail. In addition, file fragments transmitted from multiple servers must all be fragments of the same file, and a method for ensuring the sameness of these files will be described later.

When the transfer of the file fragments from the various servers 40 is all completed, the user device 20 combines the file fragments into one file based on the log file (S507), and notifies the file management system 30 of the completion of the file transfer. (S508).

7 shows an example of a log file. The log file of FIG. 7 attempts to receive 1000001 to 50000000 bytes from the third server 40 among the files having a total of 10000000 bytes, but fails to transfer the file in the middle and receives only 2000578 bytes. ) Shows the situation as received as "piece 6". The user device 20 combines the file pieces into a single file based on the transmission information of the log file as shown in FIG.

After the file transfer is completed, the received file is stored in the user device 20 with a unique file ID, and the file management system 30 indicates that the user device 20 stores a file having the file ID. I will remember. If the received file cannot guarantee the identity of the file due to a user's file modification, location change, or damage, the file may be removed or excluded from the file sharing environment.

Now, the file fragment transfer step (S506 in Fig. 5) according to the present invention will be described in detail.

The user device 20 evaluates the transmission rate each time a predetermined size packet is received from each server, and uses the same for the transmission management. The transfer speed of a server is not always constant, but it keeps changing in the middle, so if there is a server that is seriously slow or unstable during file fragment transfer, you need to replace it with another server.

In order to replace the transmission server, a candidate server list as shown in FIG. 6 is used. After determining another server having a relatively high transmission speed in the candidate server list, the server having the problem has not yet transmitted the remaining portion of the quota. Send it. There may be more than one server to replace a problematic server.

If there is no substitute server in the candidate server list, the user device 20 makes a request to the file management system to obtain an updated candidate server list, and finds an alternative server therefrom.

Next, a description will be given of a method for ensuring that the file fragments transmitted by the server are all fragments of the same file.

As mentioned above, in order for multiple devices to split and transmit a file, it must be ensured that the devices all transmit pieces of the same file. If several devices transfer pieces of files that are not identical to each other, and the user device merges them into a single file, the transferred file will be a corrupted file rather than the user's desired file.

In order to guarantee the sameness of the file, the present invention records the information of the original file in the metafile when receiving the file transfer, and compares the file to be transmitted with the information stored in the metafile when transmitting the file fragment to another user use. If the comparison results in the same file, the file is transferred. If the file is not the same file, the file management system receives a new ID and manages the file as a new file. Whether the files are identical may be specifically determined by the following method.

First, if the file size is the same using the file size information, it is determined that the file is the same.

Second, divide the file into m pieces, and record information about a portion of each piece in the metafile. When the file is transmitted to another device, it is determined that the file is the same if a certain portion of the fragment to be transmitted is compared with the information recorded in the metafile. At this time, the position and size of the predetermined portion can be adjusted according to the needs of the file management system.

Third, after dividing the file into m pieces, all contents of each piece are coded and recorded in a meta file, and when the file is later transferred to another device, the file to be sent is encoded and then meta Compare to the code written to the file. If the code is different, it determines that the file is not the same and does not send the fragment, but manages it as a new file on the whole system.

If you compare all the pieces of the fragments in the meta file and then compare them, you will be 100% sure of the identity of the files, but doing so will waste resources because the meta file is the same size as the original file. Therefore, the content of the received fragment is changed to a code of a suitable size, and then recorded in a meta file.

Here's how to code fragments of a file:

The coding functions and code sizes are chosen by the file management system for their purposes. For example, the simplest coding function is a function that sums the contents. If you put more weight on guaranteeing identity, you can use a compression method with no content loss as the coding function.

FIG. 8 is a diagram illustrating a state in which a user device receives file pieces from multiple servers and merges them into one file by the process illustrated in FIG. 5.

In FIG. 8, five servers 81-85 transmit file fragments to the user device 20, respectively, and a server having a high transmission speed transmits a larger amount. In FIG. 8, the server 83 which transmits the most amount is the fastest, and the server 81 which transmits the least amount is the slowest.

As such, by the five servers 81-85 collaboratively transmitting one file, the user device 20 can use the maximum bandwidth available to it, and thus the file transfer speed can be significantly improved. Can be.

Up to now, a method of receiving a single complete file from multiple servers has been described. However, the present invention can be used similarly when the file is actually divided and stored in various places. Therefore, the file joint transfer method and system of the present invention can be used as a distributed storage method of a large file, which will be described below.

If the file size increases, the entire file may not be able to be stored, depending on the device.In this case, a device that cannot store the entire file (referred to as device A) may divide a large file and store only a portion of the file. Allows other devices to store it. When the device A wants to see the contents of the large file, the file management system according to the present invention receives the other parts of the file, so that the contents of the file can be viewed as if the user has stored the entire file. At this time, the various parts of the files distributed and stored in the various devices are each treated as a general file by the file management system, and the file transfer process is also the same as the transfer process described above with reference to FIG.

For example, if device A could not store any large files and had to divide the file into 10 pieces so that it could be handled appropriately and distributed it to several devices including itself, device A could manage the file according to the present invention. By using the system to receive the rest of the file which is not stored by itself, the entire file can be viewed, and the file system recognizes 10 pieces as 10 general files, and the device is shown by the process shown in FIG. Send the file to A.

At this point, the file-sharing system must be able to manage these 10 independent files in successive file fragments. In addition, the device A using the entire file stores a portion of the file, and it is more efficient to store a portion that other devices do not have. To do this, the device A requests the file management system for a list of candidate servers as shown in Fig. 6 for each of the 10 files, finds the number of servers holding the respective file portions, and then the number of retained servers is the most. Save a small portion of the file.

So far, we have described how to receive pieces of a file from multiple servers and combine them into a single file, assuming the same file is distributed across multiple servers.

However, when the file is first created, it will only exist on one device. Therefore, the following describes two methods for improving the transmission speed when a file is transferred to multiple devices (1: multi-transmission situation).

First, this method is a case where a centralized file management system as shown in FIG. 2 manages the speed of devices, so that files can be transmitted from the fastest device.

That is, the file management system obtains the transmission speeds of the devices to receive the file, sorts them in the order of speed, and sends the list to the device (server) storing the file and the plurality of devices to receive the file. Based on this list, the server sends the file to the fastest device, the fastest device to the second fast device, and the second fast device to the third fast device. During the transfer, the first fast device notifies the server of the completion message when the file is complete, which acts as another server, and the device that was originally the server can transfer the file to the second fast device.

An example will be described with reference to FIG. 9. Suppose only device 0 currently has a specific file, and devices 1 through 100, sorted by speed, want to receive this file from device 0. Device 0 sends a file to device 1, and device 1 sends a file to device 2, which extends to device 100. If the transmission to device 1 is completed during the transmission, device 1 acts as a server, and device 0, which was the original server, can also transfer files to device 2. In this way, as the number of servers continues to increase, the transfer situation gradually becomes a one-to-one transfer situation, thereby improving the file transfer speed.

Secondly, this method does not require the file management system to manage the speed of the device. When the device acting as a server (referred to as device 0) requires more than a certain amount of devices that can be sent to it On the ground, it only transmits to the device with the fastest speed (refer to device # 1), and rarely transmits to the rest of the devices, leading the rest of the devices to look for another server. On the other hand, device 0 informs the file management system of device 1 as a device that will act as a new server.

When the file management system requests a list of devices acting as a server, the file management system sends device 1 to the list, and other devices view this list and attempt to receive from device 1.

Therefore, device 1 transmits to other devices within the range of data it has received so far, and simultaneously receives transmission from device 0. If there are too many devices requesting transmission in device 1, the file management system is informed of the device to which it is transmitting (called device 2) as a new server. In this way, the 1: multi transmission situation gradually changes to a multi: 1 transmission situation, thereby improving the transmission speed.

So far, the present invention has been described with a focus on the case where a file is downloaded, but may be used not only for downloading but also for streaming transmission. Streaming technology is a technology that can play video or audio content while receiving data without having to download a large file to watch the video or audio content. In this case, as in the case of downloading a file, the present invention can be applied as it is.

Although the present invention has been described using the examples, the scope of the present invention is not limited to the specific embodiments, and should be interpreted by the appended claims.

The file transfer system and method according to the present invention improves the file transfer speed by allowing users to divide and receive files from multiple servers, instead of receiving the entire file only on one server.

In addition, when a problem occurs in one of the multiple servers during the transfer, the transfer to the other server, so that the user can receive the file stably (fault-tolerant) stably.

In addition, even when a file exists in only one device and needs to be transferred to multiple devices as one device, the file transfer speed can be improved.

The file transfer system and method according to the present invention can not only use a large file that is difficult to use in the existing, but also can be used for streaming services.

Claims (25)

In the method for transferring files between devices connected via a network, Selecting a file to be transmitted by the user device; Receiving information about devices storing the file from a file management system managing file transfer, Determining one or more servers to which the file is to be transferred among the devices storing the file; Requesting each of the one or more servers to transmit any portion of the file; Receiving portions of the requested file from the one or more servers, respectively; Merging portions of the transferred file into one file. The method of claim 1, wherein determining one or more servers among the devices storing the file is selected from the fastest device. 2. The method of claim 1, wherein when requesting a portion of the file to each of the one or more servers, the faster the server, the larger the size of the requested file fragment. The method of claim 1, further comprising recording information on the received portion in a log file when receiving a portion of the requested file from each of the one or more servers. The method of claim 4, wherein when the user device merges a portion of the transmitted file into a single file, the log file refers to the log file. The method of claim 1, further comprising notifying the file management system of completion of file transfer after merging the one file. The method of claim 1, wherein in the step of receiving a portion of the requested file from each of the one or more servers, the transmission speed of each server is checked whenever a packet of a predetermined size is received. 8. The method of claim 7, wherein if there is a server whose transmission rate falls below a predetermined value, the server is replaced with another server. 10. The method of claim 8, wherein if the replacement server does not exist, receiving information about the devices storing the file and the speed of each device from the file management system to determine the replacement server therefrom. File transfer method characterized in that. The method of claim 1, wherein the device is a device capable of data communication, including a personal computer, workstation, mini computer, notebook computer, PDA, and the like. The method of claim 1, wherein the network includes a wired Internet, a wireless Internet, a local area network (LAN), an intranet, and an extranet. The method of claim 1, wherein the file to be transmitted has a common file ID in devices storing the file. The method of claim 1, wherein the file management system is one of devices connected to the network. The method of claim 1, wherein the file management system is distributed among devices connected to the network. The method of claim 1, wherein the information about the devices storing the file includes a device ID, a location of the device, and a transmission speed of the device. The method of claim 1, wherein the user device further comprises storing information about the merged single file in a meta file. The method of claim 16, wherein when transmitting the merged one file to another device, the file information is transmitted after checking whether the information on the file is the same as the information recorded in the meta file. 10. The method of claim 1, wherein said transmission comprises downloading and streaming technology. When a file is distributed and stored in a plurality of devices connected via a network, in a method for calling the file, Receiving information about devices storing respective parts of the file from a file management system managing file transfer; For each part of the file, determining one or more servers to which each part is to be transmitted, from among devices storing the part; Receiving and distributing each part of the file from each of the determined one or more servers for each part of the file; Merging each portion of the transferred file into one file. 20. The method as claimed in claim 19, wherein each part constituting the file belongs to the same file. A method for transferring files from one device to a plurality of devices in devices connected over a network, the method comprising: The one device transferring the file to the fastest one of the plurality of devices; The fastest device receiving the file transfers the file back to the second fastest device among the plurality of devices, and the second fastest device receiving the file transfers the received file to the third fastest device. Transferring the files up to the slowest device; And when the one device completes the file transfer for one of the plurality of devices, transfers the file back to another one of the plurality of devices. A method for transferring files from one device to a plurality of devices in devices connected over a network, the method comprising: The one device transmits the file to a plurality of devices; When the transmission amount exceeds the predetermined criterion during the transmission, the file is transmitted only to the fastest device among the plurality of devices, and the fastest device receives the file from the one device and simultaneously receives the file. Transmitting the file to other ones of the devices. 23. The method of claim 21 or 22, wherein said transmission comprises downloading and streaming technology. In the method of transferring the same file as the requested file, Dividing the file into predetermined pieces, and storing information of a predetermined portion of each piece in a meta file; In response to the transfer request for the file, dividing the file into the predetermined pieces and extracting information of the predetermined portion of each piece; Comparing the extracted information with information recorded in the meta file; If the comparison result is the same, transmitting the file, and if not the same, assigning a separate file ID to the file. In the method of transferring the same file as the requested file, a) dividing the file into predetermined pieces, encoding each piece by a coding function, and storing each code in a meta file; b) in response to a transfer request for the file, dividing the file into the predetermined fragments and encoding each fragment into the code and function; c) comparing the result coded in step b) with the information recorded in the meta file; d) if the comparison result is the same, transmitting the file, and if not the same, assigning a separate file ID to the file.