JP2011253432A - File distribution device, file distribution method and file distribution program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for file distribution capable of efficiently distributing files by appropriately grouping files to be multicast, to provide a method and a program for file distribution.SOLUTION: A file distribution device 201 includes: a quality control section 34 for acquiring quality information including an index of reception quality of files in a plurality of file reception devices 211; a transmission control section 32 for grouping the plurality of the file reception devices 211 into a plurality of groups based on the quality information acquired by the quality control section 34, and controlling file distribution group by group; and a transmission section 33 for multicasting the files group by group based on the control of the transmission control section 32.

Description

  The present invention relates to a file delivery apparatus, a file delivery method, and a file delivery program, and more particularly, to a file delivery apparatus, a file delivery method, and a file delivery program for multicasting a file to a plurality of file receiving apparatuses.

  With the digitization of movie content and books, efficient file distribution operations for large files are expected.

  Here, when adopting pull-type download, a system configuration that takes into account a high load in a time zone in which accesses are concentrated is necessary. On the other hand, when the push type file distribution is adopted, the minimum necessary system configuration can be designed by scheduling the distribution start timing.

  However, an increase in the number of locations, that is, the number of clients, increases the probability of occurrence of abnormal clients, and an increase in the capacity of files such as video content causes a delay in processing at the time of abnormalities and an increase in the amount of recovery data due to QoS (Quality of Service) Becomes prominent.

  There has been a demand for a system that realizes a file distribution service without providing a plurality of servers under the situation where the number of bases is increased and the capacity of a file is increased.

  An example of a conventional file distribution system is disclosed in Japanese Patent Application Laid-Open No. 2000-332751 (Patent Document 1). That is, using a communication system in which a server computer and a plurality of client computers are connected to each other via a network capable of broadcast communication, a plurality of requests from the server computer in response to a request from the client computer In the broadcast communication method for broadcasting the requested information to the client computer, the server computer receives the reception capability information related to the reception capability from each client computer to be transmitted, and transmits a plurality of transmission targets. The client computer is distributed to a plurality of multicast groups in accordance with the reception capability information received, and the requested information is broadcasted using transfer rates independent of each other for each multicast group.

  Another example of a conventional file distribution system is disclosed in Japanese Patent Laid-Open No. 2004-199578 (Patent Document 2). That is, content for distributing information held by the transmitting device to each receiving device using a communication system in which the transmitting device and a plurality of receiving devices are connected to each other via a predetermined communication network In the distribution method, the plurality of receiving devices serving as distribution destinations are divided into a plurality of groups corresponding to the maximum number of simultaneous distributions according to the capability of the transmission device according to a predetermined algorithm, and the transmission device distributes content first. In this case, each content is distributed to the first receiving device included in each group, and the content distribution status of the receiving devices belonging to each group is managed according to event information generated by the receiving device that has finished receiving the content, When reception of content at each receiving device ends, other undelivered reception within the group to which the receiving device belongs Find the location, to distribute content to other receiver of undelivered from this receiver.

  Another example of a conventional file distribution system is disclosed in Japanese Patent Application Laid-Open No. 2007-166469 (Patent Document 3). That is, a transmitting apparatus that transmits encoded symbols from a first encoded symbol set of encoded symbols obtained by encoding distribution data using a code that enables redundancy of encoded data, and receives the encoded symbols And receiving means for decoding the received encoded symbol, wherein the receiving apparatus has means for transmitting reception amount information representing the reception amount of the encoded symbol to the transmission device when decoding fails, The transmission device includes means for determining an encoded symbol to be additionally distributed based on the reception amount information.

  Another example of a conventional file distribution system is disclosed in Japanese Unexamined Patent Application Publication No. 2009-239456 (Patent Document 4). That is, when the communication module detects a packet loss of a packet transmitted / received on the transmission path, the communication module counts the number of retransmissions of the packet or the number of retransmission requests of the packet, and whether the count value is equal to or greater than a first threshold value. Control means for determining whether or not the count value is greater than or equal to the first threshold by the control means, and attenuating means for attenuating the voltage of the electrical signal transmitted and received through the transmission line, Have.

JP 2000-332751 A Japanese Patent Laid-Open No. 2004-199578 JP 2007-166469 A JP 2009-239456 A

  In the file distribution system described in Patent Document 1, the reception capability is the amount of data that can be received per unit time. The reception capability of each client computer is determined according to factors such as the capacity of the memory device included in the client computer and the performance of the CPU device.

  That is, since the file distribution system described in Patent Document 1 is configured to perform grouping of multicast destinations according to a fixed specification value of each client computer, the line state between the server and the client, and the operation state of the client There was a problem that files could not be distributed efficiently.

  In addition, Patent Documents 2 to 4 do not disclose a configuration for solving such a problem.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a file distribution apparatus and a file distribution capable of efficiently distributing files by appropriately performing grouping of multicast destinations. A method and file delivery program are provided.

  In order to solve the above-described problem, a file delivery apparatus according to an aspect of the present invention is a file delivery apparatus for delivering a file to a plurality of file reception apparatuses, and receives the file in the plurality of file reception apparatuses. Based on the quality information acquired by the quality management unit for acquiring quality information including quality indicators and the quality management unit, the plurality of file receiving devices are divided into a plurality of groups, A transmission control unit for controlling file distribution and a transmission unit for multicasting the file for each group based on the control of the transmission control unit.

  In order to solve the above-mentioned problem, a file delivery method according to an aspect of the present invention is a file delivery method for delivering a file to a plurality of file reception devices, wherein the reception quality of the file in the plurality of file reception devices is reduced. A step of acquiring quality information including an index, a step of dividing the plurality of file receiving devices into a plurality of groups based on the acquired quality information, and controlling the distribution of the files for each of the groups; And multicasting the file for each group.

  In order to solve the above-mentioned problem, a file delivery program according to an aspect of the present invention is a file delivery program in a file delivery device for delivering a file to a plurality of file receiving devices, wherein the plurality of files are transmitted to a computer. A step of acquiring quality information including an index of reception quality of the file in the receiving device, and dividing the plurality of file receiving devices into a plurality of groups based on the acquired quality information, and distributing the file for each group And a step of multicasting the file for each group based on the control.

  According to the present invention, files can be efficiently distributed by appropriately grouping multicast destinations.

It is a figure which shows the structure of the file delivery system which concerns on the 1st Embodiment of this invention, and the data flow at the time of assuming that multicasting destination grouping is not performed in a file delivery system. It is a figure which shows the structure of the file delivery system which concerns on the 1st Embodiment of this invention, and the flow of data in a file delivery system. It is a schematic block diagram of the server which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the control structure which the server and client which concern on embodiment of this invention provide. It is a flowchart which shows the operation | movement procedure at the time of the file delivery system which concerns on embodiment of this invention performing a file delivery process. It is a figure which shows an example of the content of the delivery schedule file produced in the server which concerns on the 1st Embodiment of this invention. It is a figure which shows in detail the data flow between the server and client in the file delivery system which concerns on the 1st Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

<First Embodiment>
[Overview]
In the first embodiment of the present invention, in the operation of distributing a large-capacity file such as video content to thousands or tens of thousands of bases, that is, clients, the file distribution source server (file distribution apparatus) A group in which at least one of reception quality and reception performance is similar is created while collecting reception quality and reception performance information of the previous client (file reception device). Then, the server determines the optimum transmission means for each group and performs data transmission.

  As a result, it is possible to suppress the occurrence of an abnormal client while maximizing the reception performance of the client, and to suppress unnecessary data transmission such as retransmission. It is possible to perform efficient data transmission and systematic and scheduled file distribution.

  In other words, when distributing large-capacity files such as video content to thousands or tens of thousands of sites, that is, clients, the server that distributes the files collects information about the reception quality and reception performance of each client that receives the files. Then, grouping is performed based on the quality level and the performance level, and the optimum transmission means is determined and determined for each group. This maximizes the performance of the client that receives the file, realizes efficient file distribution of the distributed data amount to multiple locations, minimizes file distribution delay, and performs the planned and scheduled Operation becomes possible.

[Configuration and basic operation]
FIG. 1 is a diagram showing a configuration of a file delivery system according to the first embodiment of the present invention and a data flow when it is assumed that multicast destination grouping is not performed in the file delivery system.

  Referring to FIG. 1, in the file distribution system 301, when distributing one data to a plurality of clients, distribution is performed using multicast transmission.

  In this multicast transmission, the server 201 issues a reception instruction to the plurality of clients 211, and transmits one packet data 71 to the network 10 for the plurality of clients 211. The client 211 receives the packet data 72 automatically copied by the router in the network 10.

  In this multicast transmission, the following QoS technology is used to completely restore the content file 3 on the server 201 without missing data in the client 211 and acquire the content file 30.

  First, the server 201 adjusts the transmission bandwidth so that all the clients 211 can stably receive the packet data 72.

  Next, the server 201 performs data transmission by adding redundant data for error correction processing to the data to be transmitted. Then, the client 211 restores unreceived data with received data including redundant data even if some data cannot be received. Further, the server 201 improves the restoration rate of unreceived data in the client 211 by adjusting the amount of redundant data.

  For the unreceived data of the client 211 that exists after performing the above-described operation, the client 211 requests the server 201 to retransmit the unreceived data. Then, the server 201 retransmits the requested data.

  However, such QoS technology has the following problems. That is, when an abnormal state such as data loss occurs in the client 211, instead of guaranteeing the integrity of the file, adjustment of the transmission band, adjustment of the redundant data amount, and data retransmission processing are performed. As a result, the file distribution completion time is delayed due to a decrease in the transmission band between the server and the client and an increase in the amount of communication data.

  Further, when the number of distribution destination clients increases, the probability of occurrence of abnormal clients increases. Further, when the capacity of the content file increases, the file distribution delay time increases, and recovery becomes difficult due to the abnormality detection delay.

  Therefore, in order to provide file distribution as a service, stable file distribution is always performed as planned, and even if an unexpected abnormal client occurs, the influence on the entire file distribution is minimized. In addition, a system that can cope with an increase in the number of clients and an increase in file capacity with a small number of operation steps is required.

  Therefore, in the first embodiment of the present invention, a file distribution system that satisfies the above requirements is provided with the following configuration.

  FIG. 2 is a diagram showing the configuration of the file delivery system according to the first embodiment of the present invention and the data flow in the file delivery system.

  Referring to FIG. 2, the file distribution system 301 includes a server (file distribution apparatus) 201 and a plurality of clients (file reception apparatuses) 211. The server 201 includes a file distribution unit 2 realized by, for example, a computer program. The client 211 includes a file receiving unit 12 realized by a computer program, for example.

  The file distribution unit 2 distributes the content file 3 from the server 201 to the client 211. More specifically, the file distribution unit 2 plans the optimal transmission means, file distribution start timing and distribution end timing to each client 211 before starting data transmission, and creates a distribution schedule file 5 indicating the contents of the plan. To do. Then, the file distribution unit 2 executes file distribution according to the distribution schedule file 5. This enables file distribution as planned.

  The file receiving unit 12 restores the content file 30 (flow F13) while receiving the transmission data from the server 201 (flow F21).

  In addition, the file reception unit 12, in order to enable the file distribution unit 2 to create the optimal distribution schedule file 5, in parallel with the reception operation and the restoration operation, the quality indicating the reception performance and reception quality of the client 211. Information 31 is collected (flow F14). Each time the file receiving unit 12 completes reception of the content file 30, the file receiving unit 12 notifies the file distribution unit 2 of the latest quality information 31 of its own client 211 (flow F15 and flow F22).

  The file distribution unit 2 receives the quality information 31 from the file reception unit 12 and collectively manages the quality information 31 collected by the file reception unit 12 in each client 211 as the quality information 4 (flow F7). Then, the file distribution unit 2 analyzes the quality information 4 to determine the optimum transmission means for each client, and groups clients having similar performance and similar quality, and determines the multicast transmission means and transmission destination. .

  Further, the file distribution unit 2 calculates a file distribution time in consideration of the occurrence of an abnormality for each group, plans a schedule of start timing and end timing for distributing the file to all clients 211, and shows the contents of the plan. A distribution schedule file 5 is created (flow F8).

  Then, the file delivery unit 2 transmits data according to the contents of the delivery schedule file 5 (flows F9 and F21).

  Further, when an abnormality occurs in any of the file receiving units 12 and the file distribution unit 2 receives a data retransmission request (flow F23) from the file receiving unit 12 in which the abnormality has occurred, the file distribution unit 2 refers to the quality information 4 of the corresponding client. (Flow F6), it is confirmed whether the retransmission request amount is within the allowable range or outside the allowable range.

  When the retransmission request amount is within the allowable range, the file distribution unit 2 executes the QoS function, and retransmits the data according to the retransmission request in order to guarantee the integrity of the file (flow F24). On the other hand, when the retransmission request amount is outside the allowable range, the file distribution unit 2 determines that the abnormal state is different from the normal state, excludes the client 211 that has made the retransmission request from the multicast distribution destination, and performs the degenerate operation. Do. The file distribution unit 2 provides a one-to-one unicast transmission unit to the client 211 excluded from the multicast distribution destination, and stores data.

  As described above, the file distribution server 201 collects and manages the reception performance and reception quality of a plurality of clients 211, thereby determining an optimal transmission means that matches the reception performance and reception quality of each client 211. , Always allowing stable file distribution.

  The server and client according to the first embodiment of the present invention typically have a basic structure of a computer having a general-purpose architecture, and execute various programs as will be described later by executing a preinstalled program. Provide functionality. In general, such a program is stored in a recording medium such as a flexible disk and a CD-ROM (Compact Disk Read Only Memory) or distributed via a network or the like.

  The program according to the first embodiment of the present invention may be provided by being incorporated in a part of another program such as an OS. Even in this case, the program itself according to the first embodiment of the present invention does not include a module included in another program as described above, and the process is executed in cooperation with the other program. Is done. In other words, the program according to the first embodiment of the present invention may be a form incorporated in such another program.

  Alternatively, some or all of the functions provided by program execution may be implemented as a dedicated hardware circuit.

  FIG. 3 is a schematic configuration diagram of a server according to the first embodiment of the present invention. Since the schematic configuration of the client 211 is the same as that of the server 201, for example, the configuration of the server 201 will be representatively described here.

  Referring to FIG. 3, a server 201 includes a central processing unit (CPU) 101 that is an arithmetic processing unit, a main memory 102, a hard disk 103, an input interface 104, a display controller 105, and a data reader / writer 106. And a communication interface 107. These units are connected to each other via a bus 121 so that data communication is possible.

  The CPU 101 performs various operations by developing programs (codes) stored in the hard disk 103 in the main memory 102 and executing them in a predetermined order. The main memory 102 is typically a volatile storage device such as a DRAM (Dynamic Random Access Memory), and stores data indicating various arithmetic processing results in addition to programs read from the hard disk 103. To do. The hard disk 103 is a non-volatile magnetic storage device, and stores various setting values in addition to programs executed by the CPU 101. The program installed in the hard disk 103 is distributed in a state of being stored in the recording medium 111 as will be described later. In addition to the hard disk 103 or instead of the hard disk 103, a semiconductor storage device such as a flash memory may be employed.

  The input interface 104 mediates data transmission between the CPU 101 and an input unit such as a keyboard 108, a mouse 109, and a touch panel (not shown). That is, the input interface 104 receives an external input such as an operation command given by the user operating the input unit.

  The display controller 105 is connected to a display 110 that is a typical example of a display unit, and controls display on the display 110. That is, the display controller 105 displays the result of image processing by the CPU 101 to the user. The display 110 is, for example, an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube).

  The data reader / writer 106 mediates data transmission between the CPU 101 and the recording medium 111. That is, the recording medium 111 is distributed in a state where a program executed by the server 201 is stored, and the data reader / writer 106 reads the program from the recording medium 111. Further, the data reader / writer 106 writes the processing result in the server 201 to the recording medium 111 in response to the internal command of the CPU 101. The recording medium 111 is, for example, a general-purpose semiconductor storage device such as CF (Compact Flash) and SD (Secure Digital), a magnetic storage medium such as a flexible disk, or a CD-ROM (Compact Disk Read Only). Memory).

  The communication interface 107 mediates data transmission between the CPU 101 and other personal computers and server devices. The communication interface 107 typically has an Ethernet (registered trademark) or USB (Universal Serial Bus) communication function. Instead of installing the program stored in the recording medium 111 in the server 201, a program downloaded from a distribution server or the like via the communication interface 107 may be installed in the server 201.

  Further, other output devices such as a printer may be connected to the server 201 as necessary.

[Control structure]
Next, a control structure for providing a content distribution function in the server 201 and a content reception function in the client 211 will be described.

  FIG. 4 is a block diagram showing a control structure provided by the server and the client according to the embodiment of the present invention. FIG. 4 shows a system for distributing content files such as videos to a plurality of locations. Each block in the file distribution unit 2 and the file reception unit 12 shown in FIG. 4 is provided by developing a program (code) stored in the hard disk 103 in the main memory 102 and causing the CPU 101 to execute it. A part or all of the control structure shown in FIG. 4 may be realized by dedicated hardware and / or a wiring circuit.

  In the server 201, the file distribution unit 2 includes a transmission schedule planning unit (transmission control unit) 32, a data transmission unit 33, and a quality data management unit 34. In the client 211, the file reception unit 12 includes a data reception unit 42, a quality data collection unit 43, and a quality data notification unit 44.

  Here, each information and each file shown in FIG. 4 is stored in the main memory 102 or the hard disk 103 shown in FIG.

  A server 201 as a transmission source of the content file 3 and a plurality of clients 211 as transmission destinations of the content file 3 are connected via the network 10.

  In the server 201, the file distribution unit 2 divides the content file 3 into a plurality of packets and transmits them to the network 10. In the plurality of clients 211, the data receiving unit 42 receives a packet from the network 10 and restores the content file 30.

  In the file distribution unit 2, the transmission schedule planning unit 32 monitors the submission and distribution contents of the content file 3 (flow F31). The transmission schedule planning unit 32 refers to and analyzes the quality information 4 of each client 211 in order to complete the file distribution to the specified client within the specified period (flow F36), so that the optimal transmission means And a distribution schedule file 5 for instructing the file distribution start time and distribution end time (flow F32).

  When the data transmission unit 33 monitors the distribution schedule file 5 (flow F33) and detects a schedule that has reached the distribution start time, the data transmission unit 33 transmits data of the content file 3 to a plurality of clients 211 in accordance with the contents of the distribution schedule file 5. Perform (flow F41).

  The quality data management unit 34 updates and manages the quality information 4 based on the quality information 31 notified from the plurality of clients 211 (flow F35).

  In the file reception unit 12, the data reception unit 42 receives the transmission data from the data transmission unit 33 and restores the content file 30 (flow F43).

  The quality data collection unit 43 monitors the data reception status of the data reception unit 42. More specifically, the quality data collection unit 43 monitors data reception performance, data lost status, CPU usage rate, disk resource usage rate, and the like, and stores these as quality information 31 (flow F44).

  When the quality data notification unit 44 completes reception of the content file 3 from the data reception unit 42, the quality data notification unit 44 notifies the file distribution unit 2 of the quality information 31 (flows F45 and F42).

[Operation]
Next, the operation of the file distribution system according to the first embodiment of the present invention will be described with reference to the drawings. In the first embodiment of the present invention, the file distribution method according to the first embodiment of the present invention is implemented by operating the file distribution system 301. Therefore, the description of the file distribution method according to the first embodiment of the present invention is replaced with the following description of the operation of the file distribution system 301. In the following description, FIG. 4 will be referred to as appropriate.

  FIG. 5 is a flowchart showing an operation procedure when the file delivery system according to the embodiment of the present invention performs file delivery processing.

  With reference to FIG. 5, first, the client 211 collects reception performance and reception quality (step S401). That is, in the file distribution system 301, the client 211 collects reception performance and reception quality, thereby enabling determination of an appropriate transmission means and quality management based on an appropriate allowable range.

  Referring to FIG. 4 again, in the file reception unit 12 in each client 211, the data reception unit 42 restores the content file 30 while receiving the multicast transmitted packet (flow F43). In parallel with this operation, the quality data collection unit 43 collects the quality information 31 indicating the reception performance and reception quality of the client 211 (flow F44).

  Here, the quality information 31 includes, for example, at least one of the following five types of quality information A to E.

  Quality information A: data reception performance. That is, this is the maximum bandwidth at which the client 211 can stably receive data. A reception band is set such that the packet lost rate does not exceed a threshold, for example, less than 1% of all packets. Normally, the reception band according to the line speed is the data reception performance. For example, the data reception performance is 2 MBps (megabits / second) for FTTH (Fiber To The Home), and ADSL (Asymmetric Digital Subscriber Line). It is set to 500 KBps (kilobits / second).

  Quality information B: Packet reception rate. In order to transmit the content file 3 via the network 10, the content file 3 is divided into a plurality of packets. The reception quality of the client 211 can be grasped from the total number of packets of the content file 3 and the number of packets received by the data receiving unit 42.

  Quality information C: coding rate (redundancy rate) and packet restoration rate of FEC (Forward Error Correction). By employing an error correction method such as FEC, even if a part of the packets is lost in the client 211, the lost packets can be restored from the received packets. The packet restoration rate is obtained by the lost packet and the restored packet. The packet restoration rate becomes quality information for determining the effectiveness of the FEC function and an appropriate coding rate.

  Quality information D: CPU usage rate at the time of data reception. With this information, it is possible to grasp the degradation status of reception quality and reception performance when another application is operating on the client 211.

  Quality information E: Disk resource, that is, the usage rate of the storage unit. With this information, it is possible to grasp the degradation status of reception quality and reception performance when another application is operating on the client 211.

  The quality data notification unit 44 in the file reception unit 12 of the client 211 notifies the quality data management unit 34 in the server 201 of the quality information 31 collected by the quality data collection unit 43 via the network 10 every time the file reception is completed ( Flows F42 and F45).

  Referring to FIG. 5 again, next, the server 201 acquires and manages the reception performance and reception quality collected by the client 211 (step S402).

  Referring to FIG. 4 again, the quality data management unit 34 receives the quality information of the plurality of clients 211 from the network 10 (flow F42). The quality data management unit 34 performs centralized management while constantly updating the quality information 4 of the plurality of clients 211 to the latest information in order to create the optimum distribution schedule file 5 (flow F35).

  Referring to FIG. 5 again, next, server 201 groups clients 211 based on similar performance and similar quality, and determines a transmission means for each group (step S403).

  Here, the distribution of the content file starts with the submission of the content to the server 201 (flow F406).

  FIG. 6 is a diagram showing an example of the contents of the distribution schedule file created in the server according to the first embodiment of the present invention.

  Referring to FIG. 6, transmission schedule planning unit 32 monitors the submission of content file 3 (flow F54). Upon confirming the content submission, the transmission schedule planning unit 32 acquires the following content information A to C necessary for file distribution from the content information 55 (flow F56).

  Content information A: distribution period. This distribution period indicates the date and time when the distribution of the content file 3 can be started and the date and time when the distribution should be completed.

  Content information B: a distribution destination list. This distribution destination list indicates a distribution destination client list of an arbitrary content file.

  Content information C: file size. This file size is information for calculating the time required to distribute the content file.

  The transmission schedule planning unit 32 extracts only the content information B of the content information 55, that is, the quality information of the client 211 instructed by the distribution destination list, from the quality information 4 of all the managed clients 211 (flow F51).

  Based on the extracted quality information 4 of the client 211, the transmission schedule planning unit 32 determines an optimal transmission unit for each client 211, and groups the clients 211 for which the same transmission unit has been determined. Information 52 is created. The group indicated by the group information 52 is a multicast transmission destination unit.

  As a method for determining the optimum transmission means, for example, the following method can be considered. That is, based on the quality information A, the transmission schedule planning unit 32 groups together the clients 211 having the same value band based on the maximum band at which each client 211 can stably receive data. Determine the transmission bandwidth of the group. For example, each client 211 is grouped into a group that transmits at 2 MBps and a group that transmits at 500 KBps.

  Alternatively, the transmission schedule planning unit 32 groups the clients 211 whose validity of the FEC function has been confirmed based on the quality information C, and determines an optimal coding rate for each group.

  Thus, by determining the optimal transmission means for each client 211, the probability that an abnormal state will occur in the client 211 during multicast transmission can be reduced.

  Referring to FIG. 5 again, next, the server 201 generates a distribution schedule file (step S404).

  Referring again to FIG. 6, the server 201 plans the file distribution start time and end time of each group within the distribution period 58 indicated by the content information A based on the content information 55, and The distribution schedule file 5 shown is generated.

  More specifically, the transmission schedule planning unit 32 calculates the required time information 53 indicating the time required for file distribution for each group based on the quality information 4 of each client 211.

  The required time information 53 has the following contents, for example. That is, the data transmission time 54 is calculated based on the file size indicated by the content information C and the determined transmission band. The redundancy time 57 is set only for the group whose FEC validity is confirmed. The transmission time of redundant data to be added is calculated based on the determined coding rate.

  Further, based on the packet lost rate that each client 211 generates within the acceptable range in the normal quality and the retransmission request generation time obtained from the quality information 4 of each client 211, the retransmission processing that can occur in the entire group is performed. The time required is calculated as the retransmission time 55.

  Further, when setting the start time and end time of each group within the distribution period, a delay time that is allowed in order not to affect the distribution schedule of the next group is calculated as a delay allowable time 56. That is, the transmission schedule planning unit 32 provides a delay allowable time at the end of the transmission period of each group, and creates a schedule that allows file distribution to be executed as planned even if an unexpected abnormal state occurs.

  The transmission schedule planning unit 32 calculates the time required for file distribution in consideration of the QoS processing time within the allowable range that occurs in the normal state in units of groups. Then, using this time, the transmission schedule planning unit 32 sets, for example, the file distribution start times 59 and 60 of the groups 1 and n, respectively, during the distribution period 58 indicated by the content information A of the content information 55.

  Referring to FIG. 5 again, next, server 201 performs file distribution according to the created distribution schedule file 5 (step S405).

  FIG. 7 is a diagram showing in detail the data flow between the server and the client in the file distribution system according to the first embodiment of the present invention.

  Referring to FIG. 7, flows F61 to F66 show processing up to the start of multicast transmission.

  The data transmission unit 33 refers to the distribution schedule file 5 and monitors the distribution start time of each group (flow F61).

  When the data transmission unit 33 detects the distribution start time of a certain group (flow F62), the data transmission unit 33 notifies the plurality of clients 211 included in the group of the multicast transmission start (flow F63).

  Each client 211 confirms the CPU usage rate and the disk resource usage rate at the start of data reception, and notifies the data transmission unit 33 whether or not another application is operating (flow F64).

  The data transmission unit 33 reschedules a specific client 211 in which another application is operating in a group of similar performance and similar quality when the performance deteriorates (flows F65 and F66). As a result, the occurrence probability of the client 211 in which an abnormal state outside the allowable range occurs is always suppressed.

  For example, when the CPU usage rate of the client 003 is high, the client 003 is rescheduled (flows F65 and F66). In the rescheduling, the data transmission unit 33 searches for a group in which transmission means that enables stable data reception even when the CPU usage rate is high, and updates the retransmission time 55 of the searched group. The client 003 is arranged in a schedule group that falls within the range of the allowable delay time 56.

  Due to the rescheduling (flows F65 and F66), the client 003 does not receive data transmitted by multicast transmission.

Flows F67 to F76 indicate multicast transmission processing.
The data transmission unit 33 starts multicast transmission to the client 211 that is the distribution destination after rescheduling, that is, the clients 001 and 002 (flow F67).

  In this multicast transmission, the optimum transmission means is determined for each group, and a band in which stable data reception is possible is set in each client 211. Therefore, the appearance probability of the client 211 in which an abnormal state outside the allowable range occurs is Lower.

  For example, when a retransmission request is generated from a specific client 001 after the start of multicast transmission (flow F68), the data transmission unit 33 refers to the quality information 31 of the client 001 and the retransmission request amount of the client 001 is within an allowable range. Check whether it is inside or outside the allowable range.

  When the amount of retransmission request is within the allowable range, the data transmission unit 33 retransmits the packet requested for retransmission by multicast (flow F71) in order to guarantee the integrity of the file by the QoS function.

  If the retransmission request amount is out of the allowable range, the data transmission unit 33 determines that the client 001 is a client in an abnormal state different from the normal state, and notifies that the client 001 is excluded from the multicast distribution destination (flow F75). . The client 001 that has received the exclusion notification does not make a retransmission request after the exclusion notification.

  As described above, by executing the QoS function of the client that has requested retransmission within the allowable range, the file distribution to the majority of clients 211 in the normal state can be completed as planned. Further, for the client 001 that is determined to be in an abnormal state and excluded from the multicast distribution destination, the data transmission unit 33 reschedules to execute the unicast distribution, that is, the function of distributing the file from the server 201 to one client 211 ( Flow F76).

Flows F77 to F78 show processing after file distribution is completed.
The client 002 that has received all the data and the client 001 that has been disconnected due to the abnormal state notify the quality data management unit 34 of the quality information 31 indicating the latest reception performance and reception quality (flow F77).

  The quality data management unit 34 constantly updates the quality information 31 indicating the reception performance and reception quality of each client 211 to the latest information (flow F78) and uses it as information on reception performance and reception quality at the time of the next content file distribution. To do.

  By the way, since the file distribution system described in Patent Document 1 is configured to perform grouping of multicast destinations according to a fixed specification value of each client computer, the line state between the server and the client, and the operation state of the client There was a problem that files could not be distributed efficiently.

  On the other hand, in the file distribution system according to the first embodiment of the present invention, the file distribution server 201 collects and manages the reception performance and reception quality of the plurality of clients 211, and the multicast destination group The optimum transmission means is determined for each. More specifically, in the server 201, the quality data management unit 34 acquires quality information 31 including an index of file reception quality in the plurality of clients 211. The transmission schedule planning unit 32 divides the plurality of clients 211 into a plurality of groups based on the quality information 31 acquired by the quality data management unit 34 and controls file distribution for each group. Then, the data transmission unit 33 multicasts the file for each group based on the control contents of the transmission schedule planning unit 32, that is, the distribution schedule file 5.

  With such a configuration, multicast destination grouping can be appropriately performed according to the line state between the server 201 and the client 211 and the operation state of the client 211, and the file can be distributed efficiently.

  In other words, in the file distribution system according to the first embodiment of the present invention, the optimum transmission means that matches the reception quality of each client is determined, and stable file distribution is always possible. By grasping the reception quality of each client in the normal state, the file integrity is guaranteed by executing the QoS function for the abnormal state within the allowable range, and the abnormal state outside the allowable range different from the normal range. By detecting this early, the effect on the entire system is minimized. In addition, by managing the reception quality of each client, it is possible to automatically plan a file distribution schedule that matches the increase in the number of clients and the capacity of the file, and to execute file distribution as planned. It becomes.

  Further, by suppressing the occurrence of an abnormal state in the client 211, the file delivery delay time caused by the recovery process of the QoS function when the abnormal state occurs can be reduced, so that the file distribution can be operated as planned.

  As described above, among the constituent elements in the server 201 according to the first embodiment of the present invention, the multicast destination group has the minimum configuration including the quality data management unit 34, the transmission schedule planning unit 32, and the data transmission unit 33. By appropriately dividing, the object of the present invention of efficiently distributing files can be achieved.

  Here, in the technique described in Patent Document 2, the recovery process at the time of occurrence of an abnormality is delivered to another server, and an optimum QoS function is appropriately selected based on the information at the time of the abnormality. That is, Patent Document 2 discloses contents related to optimization of processing when an abnormality occurs using the QoS function that is the existing technology.

  On the other hand, the file delivery system according to the first embodiment of the present invention solves the problem of delay in file delivery time due to the QoS function by not causing an abnormality. Are completely different configurations.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses contents in which a plurality of clients are grouped by line speed and a distribution band is set in units of groups.

  On the other hand, in the file distribution system according to the first embodiment of the present invention, not only the line speed but also the reception quality such as the packet reception status is appropriately collected and used as a grouping judgment criterion. Further, since the collected quality information is also used for determination of processing when an abnormality occurs, the configuration is completely different from the configuration described in Patent Document 3.

  In the file distribution system according to the first embodiment of the present invention, the data transmission unit 33 divides the file into a plurality of packets and transmits the divided packets. Then, the quality data management unit 34 acquires quality information including packet reception rates in the plurality of clients 211.

  With such a configuration, it is possible to acquire an index that appropriately indicates the line state between the server and the client and the operation state of the client.

  In the file delivery system according to the first embodiment of the present invention, the data transmission unit 33 divides the file into a plurality of packets, performs encoding for error correction processing on each packet, and transmits the packet. To do. The quality data management unit 34 acquires quality information including a restoration rate of packets that have failed to be received by the plurality of clients 211.

  With such a configuration, it is possible to acquire an index that appropriately indicates the line state between the server and the client and the operation state of the client.

  In the file distribution system according to the first embodiment of the present invention, the transmission schedule planning unit 32 assigns a plurality of clients 211 based on the restoration rate in the plurality of clients 211 acquired by the quality data management unit 34. It is divided into a plurality of groups, and the coding rate for error correction processing for the packet is determined for each group.

  With such a configuration, the FEC coding rate for the packet is optimized for each group, the retransmission request from the client 211 is suppressed, and the same packet can be prevented from being repeatedly transmitted from the server 201. Bandwidth can be used effectively.

  In the file distribution system according to the first embodiment of the present invention, the quality data management unit 34 acquires quality information including the load factors of the plurality of clients 211.

  With such a configuration, it is possible to acquire an index that appropriately indicates the operating state of the client.

  In the file distribution system according to the first embodiment of the present invention, the quality data management unit 34 acquires quality information including the usage rate of the disk resource that is the storage unit in the plurality of clients 211.

  With such a configuration, it is possible to acquire an index that appropriately indicates the operating state of the client.

  Further, in the file delivery system according to the first embodiment of the present invention, the data transmission unit 33 determines whether or not to multicast a file to the client 211 based on the quality information acquired by the quality data management unit 34. The file is unicast to the client 211 that is determined to determine that it should not be multicast. For example, the data transmission unit 33 determines that the file should not be multicast to the client 211 determined to be in an abnormal state from the packet reception rate and CPU reception rate indicated by the quality information acquired by the quality data management unit 34. .

  With such a configuration, multicast distribution and unicast distribution can be appropriately switched according to the line state between the server 201 and the client 211 and the operation state of the client 211, so that more efficient file distribution can be performed. Can be realized.

  In the file distribution system according to the first embodiment of the present invention, the data transmission unit 33 divides the file into a plurality of packets and transmits the divided packets. The quality data management unit 34 acquires retransmission request information from the client 211 indicating a packet to be retransmitted. When the total data length of the packet indicated by the retransmission request information is equal to or greater than the predetermined value, the data transmission unit 33 determines that the packet indicated by the retransmission request information should not be multicast to the client 211 and should not be multicast. The packet indicated by the retransmission request information is unicast to the client 211 that is determined to be.

  With such a configuration, it is possible to prevent a large amount of data from being multicasted repeatedly, so that the network bandwidth can be used effectively.

  Further, in the file delivery system according to the first embodiment of the present invention, the quality data management unit 34 includes a quality including a file reception quality index of the plurality of clients 211 and a reception performance index of the plurality of clients 211. Get information. Then, the transmission schedule planning unit 32 divides the plurality of clients 211 into a plurality of groups based on the reception quality and reception performance indicated by the quality information acquired by the quality data management unit 34, and controls file distribution for each group. To do.

  With such a configuration, it is possible to perform multicast destination grouping according to the line state between the server and the client, the operating state of the client, and the fixed specification value of each client, so that more efficient file distribution is possible. Can be realized.

  In the file delivery system according to the first embodiment of the present invention, the transmission schedule planning unit 32 assigns a plurality of clients 211 to a plurality of groups based on the reception performance of each client 211 and the reception quality at each client 211. In this configuration, file distribution is controlled for each group, but the present invention is not limited to this. The transmission schedule planning unit 32 does not use the reception performance of each client 211 but divides the plurality of clients 211 into a plurality of groups based on the reception quality at each client 211 and controls file distribution for each group. May be.

  The transmission schedule planning unit 32 may be configured to further subdivide the multicast destination group based on two or more of the quality information A to E.

  In the file delivery system according to the first embodiment of the present invention, the data transmission unit 33 is configured to transmit a file by dividing it into a plurality of packets, but the present invention is not limited to this. The data transmission unit 33 may be configured to transmit the entire file to each client 211 at a time.

  Next, another embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

<Second Embodiment>
The present embodiment relates to a file distribution system in which processing at the time of abnormality is changed as compared with the file distribution system according to the first embodiment. The contents other than those described below are the same as those of the file distribution system according to the first embodiment.

  In the file delivery system according to the second embodiment of the present invention, the client 211 detects an abnormal state based on at least one of its own load rate and disk resource usage rate and the packet reception loss rate. If the client 211 detects an abnormality, it does not make a retransmission request even if it fails to receive a packet other than the last packet to be received, and continues to receive the multicast packet from the server 201. Then, after receiving the last packet to be received, the client 211 transmits to the server 201 a packet that failed to be received and retransmission request information indicating an abnormal state.

  The server 201 receives the retransmission request information from the client 211, and unicasts the packet indicated by the retransmission request information to the client 211.

  Specifically, referring to FIG. 7, in the client 211, when another application is started after the start of the multicast transmission (flow F67), packet lost may occur frequently and an abnormal state may occur.

  In this case, the client 211 operates as follows. That is, first, the client 211 collects the quality information 31 and grasps the relationship between at least one of the CPU usage rate and the disk resource usage rate and the packet lost rate to determine whether the client 211 is in an abnormal state due to activation of another application. Judge whether or not.

  Next, the client 211 that has been determined to be in an abnormal state does not send a lost packet retransmission request (flow F68) to the server even if a packet lost is detected. In addition, the client 211 receives the data (flow F71) transmitted by multicast within a possible range, and creates a content file in an incomplete state.

  Next, the client 211 notifies the quality data management unit 34 of the packet that has failed to be received and the retransmission request information indicating the abnormal state and the quality information 31 (flow F77).

  Next, the quality data management unit 34 receives the retransmission request information, recognizes that the client 211 has not completed the file reception, reschedules the file distribution, and updates the distribution schedule file 5.

  Here, the client 211 receives as many multicast packets as possible. For this reason, the client 211 uses the received packets and receives only the missing packets by unicast distribution from the server 201, thereby realizing a reduction in the amount of communication data on the network and a reduction in the recovery time. Can do.

  Since other configurations and operations are the same as those of the file distribution system according to the first embodiment, detailed description thereof will not be repeated here.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  According to the present invention, for example, a large-capacity file such as movie content can be reliably delivered to movie theaters and VOD service companies throughout the country before they are released. Also, electronic newspapers can be distributed to homes by early morning after submission. In addition, electronic books that require a large amount of file time to download can be distributed to subscribers. Therefore, the present invention has industrial applicability.

  Although a part or all of the above embodiments can be described as the following supplementary notes, the scope of the present invention is not limited to the following supplementary notes.

[Appendix 1]
A file delivery device for delivering a file to a plurality of file reception devices,
A quality management unit for obtaining quality information including an index of reception quality of the file in the plurality of file reception devices;
Based on the quality information acquired by the quality management unit, the plurality of file reception devices are divided into a plurality of groups, and a transmission control unit that controls the distribution of the files for each group;
A file delivery apparatus comprising: a transmission unit for multicasting the file for each group based on the control of the transmission control unit.

[Appendix 2]
The transmission unit divides and transmits the file into a plurality of packets,
The file distribution apparatus according to appendix 1, wherein the quality management unit acquires the quality information including a reception rate of the packet in the plurality of file reception apparatuses.

[Appendix 3]
The transmission unit divides the file into a plurality of packets, performs encoding for error correction processing on each packet, and transmits the packet.
The file distribution device according to appendix 1 or 2, wherein the quality management unit acquires the quality information including a restoration rate of the packet that has failed to be received by the plurality of file reception devices.

[Appendix 4]
The transmission control unit divides the plurality of file reception devices into a plurality of groups based on the restoration rate in the plurality of file reception devices acquired by the quality management unit, and performs error correction on the packet for each group. The file delivery apparatus according to appendix 3, wherein an encoding rate for processing is determined.

[Appendix 5]
The file distribution device according to any one of appendices 1 to 4, wherein the quality management unit acquires the quality information including a load factor of the plurality of file reception devices.

[Appendix 6]
The file distribution device according to any one of appendices 1 to 5, wherein the quality management unit acquires the quality information including a usage rate of a storage unit in the plurality of file reception devices.

[Appendix 7]
The transmission unit determines whether the file should be multicast to the file reception device based on the quality information acquired by the quality management unit, and determines whether the file should be multicast to the file reception device The file delivery apparatus according to any one of appendices 1 to 6, wherein the file is unicast.

[Appendix 8]
The transmission unit divides and transmits the file into a plurality of packets,
The quality management unit obtains retransmission request information from the file reception device indicating the packet to be retransmitted,
When the total data length of the packet indicated by the retransmission request information is equal to or greater than a predetermined value, the transmission unit determines that the packet indicated by the retransmission request information should not be multicast to the file reception device, The file delivery apparatus according to any one of appendices 1 to 7, wherein the packet indicated by the retransmission request information is unicast to the file reception apparatus that is determined not to be.

[Appendix 9]
The quality management unit obtains quality information including an index of reception quality of the files in the plurality of file reception devices, and an index of reception performance of the plurality of file reception devices;
The transmission control unit divides the plurality of file reception devices into a plurality of groups based on the reception quality and the reception performance indicated by the quality information acquired by the quality management unit, 9. The file delivery apparatus according to any one of appendices 1 to 8, which controls delivery.

[Appendix 10]
A file delivery system comprising a file delivery device for delivering a file and a plurality of file receiving devices for receiving the file,
The file delivery device transmits the file divided into a plurality of packets,
The file receiving device detects an abnormal state based on at least one of its own load factor and usage rate of the storage unit and the reception loss rate of the packet, and when detecting an abnormality, the file to be received last Even if reception of a packet other than a packet fails, reception of the packet multicast from the file distribution device is continued, and after receiving the packet to be received last, the reception of the packet to the file distribution device has failed. Send retransmission request information indicating the packet and abnormal condition,
The file distribution system, wherein the file distribution apparatus receives the retransmission request information from the file reception apparatus and unicasts the packet indicated by the retransmission request information to the file reception apparatus.

[Appendix 11]
A file delivery method for delivering a file to a plurality of file receiving devices,
Obtaining quality information including an index of reception quality of the file in the plurality of file reception devices;
Dividing the plurality of file reception devices into a plurality of groups based on the acquired quality information, and controlling the distribution of the files for each of the groups;
Multicasting the file for each group based on the control.

[Appendix 12]
In the step of multicasting the file, the file is divided into a plurality of packets and transmitted,
12. The file delivery method according to appendix 11, wherein in the step of obtaining the quality information, the quality information including a reception rate of the packet in the plurality of file reception devices is obtained.

[Appendix 13]
In the step of multicasting the file, the file is divided into a plurality of packets, each of the packets is encoded for error correction processing, and transmitted.
13. The file delivery method according to appendix 11 or 12, wherein, in the step of obtaining the quality information, the quality information including a restoration rate of the packet that has failed to be received by the plurality of file receiving apparatuses is obtained.

[Appendix 14]
In the step of controlling the delivery of the file, the plurality of file receiving devices are divided into a plurality of groups based on the obtained restoration rate in the plurality of file receiving devices, and an error correction process for the packet for each group 14. The file delivery method according to appendix 13, wherein a coding rate for determining is determined.

[Appendix 15]
15. The file distribution method according to any one of appendices 11 to 14, wherein, in the step of acquiring the quality information, the quality information including a load factor of the plurality of file reception devices is acquired.

[Appendix 16]
16. The file distribution method according to any one of appendices 11 to 15, wherein in the step of acquiring the quality information, the quality information including a usage rate of a storage unit in the plurality of file reception devices is acquired.

[Appendix 17]
In the step of multicasting the file, it is determined whether or not the file should be multicast to the file receiving device based on the acquired quality information, and the file is transferred to the file receiving device determined not to be multicast. The file delivery method according to any one of appendices 11 to 16, wherein the file is unicast.

[Appendix 18]
In the step of multicasting the file, the file is divided into a plurality of packets and transmitted,
In the step of acquiring the quality information, acquiring retransmission request information from the file receiving device indicating the packet to be retransmitted,
In the step of multicasting the file, if the total data length of the packet indicated by the retransmission request information is greater than or equal to a predetermined value, the packet indicated by the retransmission request information should not be multicast to the file receiving device. 18. The file delivery method according to any one of appendices 11 to 17, wherein the file unicasting is performed and the packet indicated by the retransmission request information is unicast to the file reception device that is determined to be not to be multicast.

[Appendix 19]
In the step of acquiring the quality information, the quality information including an index of the reception quality of the file in the plurality of file reception devices, and an index of reception performance of the plurality of file reception devices is acquired,
In the step of controlling the delivery of the file, the plurality of file reception devices are divided into a plurality of groups based on the reception quality and the reception performance indicated by the acquired quality information, and the file delivery is performed for each group. The file delivery method according to any one of appendices 11 to 18, wherein the file delivery method is controlled.

[Appendix 20]
A file delivery method in a file delivery system comprising a file delivery device for delivering a file and a plurality of file receiving devices for receiving the file,
The file delivery device dividing the file into a plurality of packets for transmission;
The file receiving device detects an abnormal state based on at least one of its own load factor and storage unit usage rate and the packet reception loss rate, and when detecting an abnormality, the file to be received last Even if reception of a packet other than a packet fails, reception of the packet multicast from the file distribution device is continued, and after receiving the packet to be received last, the reception of the packet to the file distribution device has failed. Sending a packet and retransmission request information indicating an abnormal condition;
A file delivery method comprising: the file delivery device receiving the retransmission request information from the file reception device and unicasting the packet indicated by the retransmission request information to the file reception device.

[Appendix 21]
A file delivery program in a file delivery device for delivering a file to a plurality of file reception devices, comprising:
Obtaining quality information including an index of reception quality of the file in the plurality of file reception devices;
Dividing the plurality of file reception devices into a plurality of groups based on the acquired quality information, and controlling the distribution of the files for each of the groups;
A file distribution program that executes the step of multicasting the file for each group based on the control.

[Appendix 22]
In the step of multicasting the file, the file is divided into a plurality of packets and transmitted,
The file distribution program according to appendix 21, wherein in the step of acquiring the quality information, the quality information including a reception rate of the packet in the plurality of file reception devices is acquired.

[Appendix 23]
In the step of multicasting the file, the file is divided into a plurality of packets, each of the packets is encoded for error correction processing, and transmitted.
23. The file distribution program according to appendix 21 or 22, wherein in the step of acquiring the quality information, the quality information including a restoration rate of the packet that has failed to be received by the plurality of file reception devices is acquired.

[Appendix 24]
In the step of controlling the delivery of the file, the plurality of file receiving devices are divided into a plurality of groups based on the obtained restoration rate in the plurality of file receiving devices, and an error correction process for the packet for each group 24. The file distribution program according to attachment 23, which determines a coding rate for

[Appendix 25]
The file distribution program according to any one of appendices 21 to 24, wherein in the step of acquiring the quality information, the quality information including a load factor of the plurality of file reception devices is acquired.

[Appendix 26]
The file distribution program according to any one of appendices 21 to 25, wherein in the step of acquiring the quality information, the quality information including a usage rate of a storage unit in the plurality of file reception devices is acquired.

[Appendix 27]
In the step of multicasting the file, it is determined whether or not the file should be multicast to the file receiving device based on the acquired quality information, and the file is transferred to the file receiving device determined not to be multicast. The file delivery program according to any one of appendices 21 to 26, wherein the file delivery program is unicast.

[Appendix 28]
In the step of multicasting the file, the file is divided into a plurality of packets and transmitted,
In the step of acquiring the quality information, acquiring retransmission request information from the file receiving device indicating the packet to be retransmitted,
In the step of multicasting the file, if the total data length of the packet indicated by the retransmission request information is greater than or equal to a predetermined value, the packet indicated by the retransmission request information should not be multicast to the file receiving device. 28. The file delivery program according to any one of appendices 21 to 27, wherein the file delivery program determines and unicasts the packet indicated by the retransmission request information to the file reception device that is determined not to be multicast.

[Appendix 29]
In the step of acquiring the quality information, the quality information including an index of the reception quality of the file in the plurality of file reception devices, and an index of reception performance of the plurality of file reception devices is acquired,
In the step of controlling the delivery of the file, the plurality of file reception devices are divided into a plurality of groups based on the reception quality and the reception performance indicated by the acquired quality information, and the file delivery is performed for each group. The file delivery program according to any one of appendices 21 to 28, which controls

[Appendix 30]
A file delivery program in a file delivery system comprising a file delivery device for delivering a file and a plurality of file receiving devices for receiving the file, the computer comprising:
The file delivery device dividing the file into a plurality of packets for transmission;
The file receiving device detects an abnormal state based on at least one of its own load factor and storage unit usage rate and the packet reception loss rate, and when detecting an abnormality, the file to be received last Even if reception of a packet other than a packet fails, reception of the packet multicast from the file distribution device is continued, and after receiving the packet to be received last, the reception of the packet to the file distribution device has failed. Sending a packet and retransmission request information indicating an abnormal condition;
A file distribution program in which the file distribution apparatus receives the retransmission request information from the file reception apparatus and causes the file reception apparatus to execute a step of unicasting the packet indicated by the retransmission request information.

2 File distribution unit 4 Quality information 5 Distribution schedule file 12 File reception unit 31 Quality information 32 Transmission schedule planning unit (transmission control unit)
33 Data transmission unit 34 Quality data management unit 42 Data reception unit 43 Quality data collection unit 44 Quality data notification unit 101 CPU
102 Main Memory 103 Hard Disk 104 Input Interface 105 Display Controller 106 Data Reader / Writer 107 Communication Interface 108 Keyboard 109 Mouse 110 Display 111 Recording Medium 121 Bus 201 Server (File Distribution Device)
211 Client (file receiving device)
301 File distribution system

Claims (10)

A file delivery device for delivering a file to a plurality of file reception devices,
A quality management unit for obtaining quality information including an index of reception quality of the file in the plurality of file reception devices;
Based on the quality information acquired by the quality management unit, the plurality of file reception devices are divided into a plurality of groups, and a transmission control unit that controls the distribution of the files for each group;
A file delivery apparatus comprising: a transmission unit for multicasting the file for each group based on the control of the transmission control unit. The transmission unit divides and transmits the file into a plurality of packets,
The file distribution apparatus according to claim 1, wherein the quality management unit acquires the quality information including a reception rate of the packet in the plurality of file reception apparatuses. The transmission unit divides the file into a plurality of packets, performs encoding for error correction processing on each packet, and transmits the packet.
The file distribution apparatus according to claim 1, wherein the quality management unit acquires the quality information including a restoration rate of the packet that has failed to be received by the plurality of file reception apparatuses.   The transmission control unit divides the plurality of file reception devices into a plurality of groups based on the restoration rate in the plurality of file reception devices acquired by the quality management unit, and performs error correction on the packet for each group. The file delivery apparatus according to claim 3, wherein an encoding rate for processing is determined.   The file distribution apparatus according to claim 1, wherein the quality management unit acquires the quality information including a load factor of the plurality of file reception apparatuses.   The file distribution device according to claim 1, wherein the quality management unit acquires the quality information including a usage rate of a storage unit in the plurality of file reception devices.   The transmission unit determines whether the file should be multicast to the file reception device based on the quality information acquired by the quality management unit, and determines whether the file should be multicast to the file reception device The file delivery apparatus according to claim 1, wherein the file is unicast. The quality management unit obtains quality information including an index of reception quality of the files in the plurality of file reception devices, and an index of reception performance of the plurality of file reception devices;
The transmission control unit divides the plurality of file reception devices into a plurality of groups based on the reception quality and the reception performance indicated by the quality information acquired by the quality management unit, The file delivery apparatus according to any one of claims 1 to 7, which controls delivery. A file delivery method for delivering a file to a plurality of file receiving devices,
Obtaining quality information including an index of reception quality of the file in the plurality of file reception devices;
Dividing the plurality of file reception devices into a plurality of groups based on the acquired quality information, and controlling the distribution of the files for each of the groups;
Multicasting the file for each group based on the control. A file delivery program in a file delivery device for delivering a file to a plurality of file reception devices, comprising:
Obtaining quality information including an index of reception quality of the file in the plurality of file reception devices;
Dividing the plurality of file reception devices into a plurality of groups based on the acquired quality information, and controlling the distribution of the files for each of the groups;
A file distribution program that executes the step of multicasting the file for each group based on the control.

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