JP2010113573A - Content distribution storage system, content storage method, server device, node device, server processing program and node processing program - Google Patents

Abstract

Content distributed storage system, content storage method, node device, and node processing program capable of reducing concentration of access to node device storing replica and preventing congestion of communication line due to download I will provide a.
When a node device obtains and stores content copy data related to a new content copy data storage request, the node device determines whether there is related content associated with the content related to the storage request. If it is determined that there is the related content, the node device that stores the copy data of the related content is searched, and the content storage request information is transmitted to the searched node device.
[Selection] Figure 4

Description

  The present invention relates to a technical field of a peer-to-peer (P2P) type communication system including a plurality of node devices that can communicate with each other via a network.

  In this type of peer-to-peer communication system, duplicate data (hereinafter referred to as “replica”) of a plurality of contents (contents such as movies and music data) is distributed and stored (arranged) in a plurality of node devices. A distributed content storage system that makes it possible to use replicas between devices is known, which improves fault tolerance and access dispersibility. The location of the replicas thus distributed and stored can be efficiently searched using a distributed hash table (hereinafter referred to as DHT (Distributed Hash Table)) as disclosed in, for example, Patent Document 1. The DHT is stored in each node device, and node information (for example, including IP addresses and port numbers) indicating a plurality of node devices to which various messages are to be transferred is registered in the DHT. .

When the node device participating in the distributed content storage system acquires desired content, the node device transmits a message (query) for searching (discovering) the location of the replica of the content to another node device. As a result, the message is transferred by the relay node device to the managing node device of the content replica in accordance with the DHT. Then, the node device that has transmitted the message acquires information indicating the location of the replica from the node device of the management source that finally reaches the message. As a result, the node device that has transmitted the message can access the node device that stores the replica of the content related to the search and download the replica.
JP 2006-197400 A

  By the way, in such a distributed content storage system, content immediately after being available, popular content, and the like are concentrated on access to node devices that store replicas of the content. For this reason, there is a problem that the response is lowered and it takes time to download the replica. Another problem is that the communication line is congested due to the download of the replica.

  The present invention has been made in view of the above points and the like, and content distribution capable of reducing concentration of access to a node device storing a replica and preventing congestion of a communication line due to downloading. It is an object to provide a storage system, a content storage method, a node device, and a node processing program.

  In order to solve the above-described problem, the invention according to claim 1 is a distributed content storage system including a plurality of node devices that can communicate with each other via a network. The node device in the content distributed storage system that is stored in a distributed manner and can use the content among the respective node devices, the storage device having a storage area for storing the duplicate data, and other From the node device or the server device having the copy data of all the content, from the storage request receiving means for receiving the content storage request information indicating the storage request for the copy data of the new content, from the other node device or the server device, A copy of the content related to the storage request is acquired and stored in a storage area in the storage means. Content storage means for performing content determination, and content determination means for determining whether there is content related to the new content related to the storage request in advance and already available between the node devices; When it is determined that there is related content associated with the new content, node search means for searching for another node device storing duplicate data of the related content, and the searched other Storage request transmission means for transmitting content storage request information indicating a request to store the new content copy data to the node device.

  According to the present invention, when the node device acquires and saves the copy data of the content related to the save request for the copy data of the new content, whether or not there is related content associated with the content related to the save request. If it is determined that there is related content, the node device that stores the copy data of the related content is searched, and the content storage request information is transmitted to the searched node device. With this configuration, it is possible to store (pre-cache) the duplicate data of the new content in advance in the node Nn of the user who is likely to use (for example, view) the new content. Reduces concentration of access to the node device that stores the network, and prevents the communication line from becoming congested due to download Door can be.

  According to a second aspect of the present invention, in the node device according to the first aspect, in the case where a plurality of the related contents are associated with the new content, the node search unit assigns each of the related contents in advance. Based on the rank information, any one of the related contents is selected, and another node device storing copy data of the selected related contents is searched.

  According to the present invention, it is possible to preferentially store the duplicate data in a node device that is highly likely to use new content.

  According to a third aspect of the present invention, in the node device according to the second aspect, after a lapse of a predetermined time from transmission of the content storage request information to another node device storing the selected one related content. The node search means selects any other related content and searches for another node device that stores duplicate data of the selected related content.

  According to a fourth aspect of the present invention, in the node device according to the first aspect, in the case where a plurality of the related contents are associated with the new content, the node search means uses the duplicate data of the related contents A plurality of other node devices that are stored are searched, and among the plurality of other node devices that are searched, other node devices that store duplicate data of two or more related contents are selected, and the storage is performed. The request transmission means transmits content storage request information indicating a storage request for the copy data of the new content to the selected other node device.

  According to the present invention, it is possible to preferentially store the duplicate data in a node device that is highly likely to use new content.

  According to a fifth aspect of the present invention, in the node device according to the first aspect, when there are two or more new contents, the same related contents are associated with each of the new contents. The image processing apparatus further includes association releasing means for releasing the association of the same related content from the new content.

  According to the present invention, it is possible to more efficiently distribute duplicate data of a plurality of new contents and save the storage capacity of the contents storage area.

  According to a sixth aspect of the present invention, in the node device according to the fifth aspect, the disassociation unit is configured to obtain the same related content from the new content having a larger number of the related content associated with the node. It is characterized by releasing the association.

  According to the present invention, it is possible to more efficiently distribute duplicate data of a plurality of new contents and save the storage capacity of the contents storage area.

  The invention according to claim 7 is a content distributed storage system including a plurality of node devices that can communicate with each other via a network, wherein duplicate data of a plurality of contents is distributed and stored in a plurality of node devices, A server device that manages duplicate data of the content in a distributed content storage system that enables the content to be used between the node devices, and any one of the plurality of node devices in the distributed content storage system. Node selecting means for selecting, duplicate data of new content, and information indicating related content that is pre-associated with the new content and is already available between the node devices, Related content information transmission means for transmitting to the selected node device; In the case where there are two or more new contents, and the same related contents are associated with each of the new contents, before the transmission of the information indicating the related contents, the same contents from any of the new contents An association releasing unit for releasing the association of the related content.

  According to an eighth aspect of the present invention, in the server device according to the seventh aspect, the association releasing means determines the same related content from the new content having a larger number of the related content items associated with the server. It is characterized by releasing the association.

  The invention of a node processing program according to a ninth aspect is characterized in that a computer is caused to function as the node device according to any one of the first to sixth aspects.

  The invention of a server processing program according to a tenth aspect is characterized in that a computer is caused to function as the server device according to the seventh or eighth aspect.

  The invention according to claim 11 is a content distributed storage system including a plurality of node devices that can communicate with each other via a network, wherein duplicate data of a plurality of contents is distributed and stored in a plurality of node devices, In the content distributed storage system in which the content can be used between the node devices, the node device includes storage means having a storage area for storing the replicated data, and replicated data of another node device or all content A storage request receiving means for receiving content storage request information indicating a request for storing new content copy data from a server device, and content copy data related to the storage request from the other node device or the server device And content storage means for storing in a storage area in the storage means, Content judging means for judging whether or not there is related content that is pre-associated with new content related to the storage request and is already available among the respective node devices; and the new content When it is determined that there is related content that is related, node search means for searching for another node device that stores duplicate data of the related content, and for the searched other node device Storage request transmission means for transmitting content storage request information indicating a storage request for the copy data of the new content.

  The invention according to claim 12 is a content distributed storage system comprising a plurality of node devices that can communicate with each other via a network, wherein duplicate data of a plurality of contents is distributed and stored in a plurality of node devices, A content storage method in a distributed content storage system in which the content can be used between the node devices, wherein the node device receives a new content from another node device or a server device having duplicate data of all content. A storage request reception step of receiving content storage request information indicating a storage request for copy data; and the node device acquires copy data of the content related to the storage request from the other node device or the server device, and A content storage step of storing in a storage area for storing duplicate data; and A content determination step of determining whether there is a related content that is pre-associated with the new content related to the storage request and is already available between the node devices; When the node device determines that there is related content associated with the new content, a node search step of searching for another node device that stores duplicate data of the related content; and The node device includes a storage request transmission step of transmitting content storage request information indicating a storage request for the copy data of the new content to the other node device searched.

  According to the present invention, when the node device acquires and stores the copy data of the content related to the storage request for the copy data of the new content, whether or not there is related content associated with the content related to the storage request. If it is determined that there is related content, the node device that stores the copy data of the related content is searched, and the content storage request information is transmitted to the searched node device. With this configuration, it is possible to store (pre-cache) the duplicate data of the new content in advance in the node Nn of the user who is likely to use (for example, view) the new content. The concentration of access to the node device that stores the traffic is reduced, and the communication line is prevented from being congested by downloading. Can.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best embodiment of the invention will be described with reference to the drawings. The embodiment described below is an embodiment when the present invention is applied to a content distributed storage system.

[ 1. Outline and configuration of distributed content storage system ]
First, with reference to FIG. 1 etc., the structure and operation | movement outline | summary of the content distribution preservation | save system which concern on this embodiment are demonstrated.

  FIG. 1 is a diagram showing an example of a connection mode of each node device in the distributed content storage system according to this embodiment.

  As shown in the lower frame 101 of FIG. 1, IX (Internet eXchange) 3, ISP (Internet Service Provider) 4a, 4b, DSL (Digital Subscriber Line) line operators (devices) 5a, 5b, FTTH (Fiber To A network (real-world communication network) 8 such as the Internet is constructed by a line provider (device) 6 and a communication line (for example, a telephone line or an optical cable) 7. Note that a router for transferring data (packets) is appropriately inserted into the network 8 in the example of FIG.

  A plurality of node devices (hereinafter referred to as “nodes”) Nn (n = 1, 2, 3,...) Are connected to such a network 8. Each node Nn is assigned a unique manufacturing number and an IP (Internet Protocol) address. The content distributed storage system S according to the present embodiment is a peer-to-peer network system formed by participation of any of a plurality of nodes Nn, as shown in the upper frame 100 of FIG. It has become.

  A network 9 shown in the upper frame 100 of FIG. 1 is an overlay network 9 (logical network) that forms a virtual link formed using the existing network 8. Such an overlay network 9 is realized by a specific algorithm, for example, an algorithm using DHT. Each node Nn participating in the content distributed storage system S (in other words, the overlay network 9) is assigned a node ID, which is unique identification information having a predetermined number of digits. The node ID is, for example, a value (for example, the bit length is 160 bits) obtained by hashing an IP address or a manufacturing number individually assigned to each node Nn with a common hash function (for example, SHA-1). Yes, it will be distributed in one ID space without any bias.

  In addition, participation in the content distributed storage system S is performed by any node Nn (for example, the node N8) that has not participated in any node Nn (for example, a contact node that always participates in the system S) that has not participated. This is done by sending a participation message indicating a participation request.

  Each node Nn holds a routing table using DHT. This routing table defines the transfer destinations of various messages on the content distributed storage system S, specifically, a node including the node ID, IP address, and port number of a node Nn that is moderately separated in the ID space Multiple pieces of information are registered.

  One node Nn participating in the content distributed storage system S registers the minimum necessary node information of the nodes Nn among all the nodes Nn participating in the system S in the routing table, With respect to the node Nn that does not know (store) the node information, various messages are transferred between the nodes Nn to be delivered.

  Such a routing table using DHT is well known in Japanese Patent Application Laid-Open No. 2006-197400 and the like, and will not be described in detail.

  By the way, in the content distributed storage system S, replicas of various contents having different contents (for example, movies, music, etc.) are distributed (stored) in a plurality of nodes Nn in a predetermined file format. The replica can be used between Nn. For example, the node N5 stores a replica of the movie content with the title XXX, while the node N3 stores a replica of the movie content with the title YYY. (Hereinafter referred to as “content holding nodes”).

  In addition, information such as a content name (title) and a content ID (identification information unique to each content) is added to each of these content replicas. This content ID is generated, for example, by hashing the content name + arbitrary numerical value (or may be the first few bytes of the content data) with a hash function common to obtaining the node ID (node ID and Placed in the same ID space). Alternatively, the system administrator may give a unique ID value (same bit length as the node ID) for each content. In this case, the content catalog information in which the correspondence between the content name and the content ID is written is distributed to all the nodes Nn.

  In addition, the location of the replica of the content that is distributed and stored in this way, that is, the index information that includes the node information of the node Nn that stores the replica and the content ID of the content is the location of the replica of the content. Is stored (stored in the index cache) and managed by a node Nn (hereinafter referred to as “root node” or “root node of content (content ID)”) or the like.

  That is, the node information of the content holding node storing the content replica is managed by the root node so as to be provided in response to an inquiry from another node Nn.

  For example, the index information about the replica of the movie content with the title XXX is managed by the node N4 which is the root node of the content (content ID), and the index information about the replica of the movie content with the title YYY is Managed by the node N7 which is the root node of the content (content ID). Further, such a root node is determined to be, for example, a node Nn having a node ID closest to the content ID (for example, the higher-order digits match more).

  When a user of a certain node Nn wants to acquire a replica of the desired content, the node Nn that desires to acquire the replica (hereinafter referred to as “user node”) determines the content ID and the self of the content selected by the user. A content location inquiry (search) message (query) including the IP address of the client is generated and sent to another node Nn according to a routing table using its own DHT. That is, the user node sends a content location inquiry (search) message to the root node (to the root node) (inquires the location of the content replica to the root node). As a result, the content location inquiry (search) message finally arrives at the root node by DHT routing using the content ID as a key.

  The attribute information such as the content name and content ID of the content to be selected by the user in each node Nn is described in, for example, content catalog information distributed from the content providing server SA to all the nodes Nn.

  The content ID included in the content location inquiry (search) message may be generated by the user node by hashing the content name with the common hash function. The DHT routing is known in Japanese Patent Application Laid-Open No. 2006-197400 and the like, and thus detailed description thereof is omitted.

  The root node that receives the content location inquiry (search) message acquires index information corresponding to the content ID included in the content node from the index cache, and uses the index information as a user who is the transmission source of the content location inquiry message. Reply to the node. The user node that has acquired the index information in this way accesses the content holding node based on the IP address of a content holding node included in the index information, transmits a content transmission request message, and then acquires a content replica therefrom. It becomes possible to download (acquire).

  The root node transmits a content transmission request message to the content holding node indicated by the IP address or the like included in the index information, whereby the user node downloads the replica from the content holding node. You can also. The user node can also acquire the index information from a cache node that caches the same index information as the root node until the content location inquiry message reaches the root node.

  In addition, the user node that has stored the replica of the content acquired from the content holding node informs the root node that the replica has been stored (in other words, for other nodes Nn participating in the system S). A publish (registration notification) message including the content ID of the replica and its own node information, and sends the publish message to the root node (to the root node).

  As a result, the publish message arrives at the root node by DHT routing using the content ID as a key, like the content location inquiry (search) message. Then, the root node registers (stores in the index cache area) index information including a set of node information and content ID included in the received publish message. In this way, the user node becomes a new content holding node that holds a replica of the content.

  Note that the index information including the set of node information and content ID included in the publish message is also registered (cached) in the cache node in the transfer path to the root node.

[ 2. Configuration and function of content providing server SA ]
Next, the configuration and function of the content providing server SA (an example of a server device) will be described with reference to FIG.

  FIG. 2 is a diagram illustrating a schematic configuration example of the content providing server SA.

  As shown in FIG. 2, the content providing server SA is controlled as a computer composed of a CPU having a calculation function, a working RAM, various data, and a ROM for storing programs (including the server processing program of the present invention). Unit 11, a storage unit 12 composed of an HD (hard disk) for storing and saving various data and various programs, a display unit 13 for displaying various types of information, and an instruction from an administrator, etc. An input unit 14 for giving an instruction signal corresponding to the instruction to the control unit 11 and a communication unit 15 for controlling communication of information with the node Nn and the like through the network 8 are configured. Are connected to each other via a bus 16. The server processing program may be downloaded from a predetermined server on the network 8, for example, or recorded on a recording medium such as a CD-ROM and read via a drive of the recording medium. You may make it. The content providing server SA manages node information of several nodes Nn participating in the content distributed storage system S.

  The storage unit 12 stores a content information list in which information of a plurality of contents that are newly scheduled to be input to the content distributed storage system S is described. In this content information list, for example, an evaluation value, a release date, related content information, a size (data amount), and the like are registered in association with each content ID. Registration of content information in the content information list is performed by, for example, an administrator.

  Here, the evaluation value is a value determined according to the expected number of accesses (in other words, the popularity of the content) as disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-34630. That is, the evaluation value increases as the expected number of accesses increases.

  The release date / time indicates, for example, the date / time when the content can be used in each node Nn. For example, the release date / time is the date / time at which the content to be acquired in each node Nn can be selected on the content catalog information (until the release date / time cannot be selected on the content catalog information).

  The related content information includes information indicating whether or not there is related content that is previously associated with the new content and is already available between the nodes Nn. When there is content, the related content information includes the content ID of the related content.

  Here, the association of the related content with the new content is performed, for example, by a new content provider (for example, a distribution vendor). For example, another content whose content is similar to that of the new content (determined by the provider) is associated as the related content. When the new content is a movie content, the content of another movie with the same director or the same star as the movie is associated as the related content. In addition, when the new content is the content of the music, another music of the same artist (eg, singer, performer) or composer as the music is associated as related content. When the new content is the content of the second episode of the drama of the series in which all the episodes are completed, the content of the first episode is associated as the related content.

  Also, the related content associated with the new content is not necessarily one, and there may be a plurality of cases. In this case, each related content has rank information indicating a ranking that is strongly associated with the new content. Is granted. For example, when three related contents A, B, and C are associated with a new content X, rank information indicating the first ranking (strongest connection with the newest content) is given to the related content B The related content A is assigned rank information indicating the second ranking, and the related content C is provided rank information indicating the third ranking.

  In such a configuration, the control unit 11 performs overall control by reading and executing a program stored in the storage unit 12 or the like by the CPU, and serves as a node selection unit, a related content information transmission unit, and the like in the present invention. Function.

  Specifically, the control unit 11 selects a predetermined number of contents (for example, the release date is the same or close) from the contents registered in the content information list, and further selects a node Nn that is the input destination. To do. And the control part 11 transmits the preservation | save request message (an example of content preservation | save request information) which shows the preservation | save request | requirement of the selected content replica, and the preservation | save of the content which concerns on the said preservation | save request is permitted by the said node Nn, A replica of the content related to the storage request is transmitted to the node Nn.

  The save request message includes the content ID, evaluation value, release date, related content information, size, and the like of the content related to the save request.

[ 3. Configuration and function of node Nn ]
Next, the configuration and function of the node Nn will be described with reference to FIG.

  FIG. 3 is a diagram illustrating a schematic configuration example of the node Nn.

  As shown in FIG. 3, each node Nn includes a control unit 21 including a CPU having a calculation function, a working RAM, a ROM for storing various data and programs, and various data (for example, a replica of content data, Index information, DHT, etc.) and a storage unit 22 composed of an HD (hard disk) for storing and storing various programs, a buffer memory 23 for temporarily storing received content data replicas, etc. A decoder unit 24 that decodes (data expansion, decoding, etc.) encoded video data (video information) and audio data (audio information) included in the replica, and a predetermined drawing for the decoded video data, etc. Video processing unit 25 that performs processing and outputs the video signal, and the video processing A display unit 26 such as a CRT or a liquid crystal display for displaying an image based on the video signal output from 25, and the decoded audio data is converted into an analog audio signal by D (Digital) / A (Analog) and then this is amplified by an amplifier. Communication of information between the audio processing unit 27 that amplifies and outputs, the speaker 28 that outputs the audio signal output from the audio processing unit 27 as a sound wave, and the other nodes Nn and the content management server SA through the network 8 A communication unit 29 for performing control, and an input unit 30 (for example, a keyboard, a mouse, or an operation panel) that receives an instruction from the user and provides an instruction signal corresponding to the instruction to the control unit 21. A control unit 21, a storage unit 22, a buffer memory 23, a decoder unit 24, a communication unit 29, and an input. Part 30 is connected to each other via a bus 31. As the node Nn, a personal computer, an STB (Set Top Box), a TV receiver, or the like can be applied.

  The storage unit 22 stores content replicas, DHT, index information (stored in the index cache area), content catalog information, and the like. In the storage unit 22, the capacity (for example, 100 gigabytes) of the content storage area for storing and storing content replicas can be arbitrarily set by the user, for example.

  Further, the storage unit 22 stores a content information list. In the content information list, the content ID, evaluation value, release date, related content information, size, and the like of the content for which the replica is actually stored in the storage unit 22 are registered.

  In the configuration as described above, the control unit 21 performs overall control by reading and executing a program (including the node processing program of the present invention) stored in the storage unit 22 or the like, and distributes and stores content. By participating in the system S, processing as at least one of the above-described user node, relay node, root node, cache node, and content holding node is performed. The node processing program may be downloaded from a predetermined server on the network 8, for example, or recorded on a recording medium such as a CD-ROM and read via the drive of the recording medium. You may make it.

  Further, the control unit 21 functions as a storage request reception unit, a content storage unit, a content determination unit, a node search unit, a storage request transmission unit, and the like in the present invention.

  More specifically, the control unit 21 receives from the content providing server SA or the content holding node a storage request message indicating a storage request for a replica of a new content before publication in the content distributed storage system S. If the content storage area has enough free space to store the replica of the content related to the storage request, the control unit 21 sends the storage request from the content providing server SA or the content holding node that is the transmission source of the storage request message. A replica of the content related to the request is acquired (downloaded), and the replica is stored in the content storage area in the storage unit 22. On the other hand, when there is not enough free space in the content storage area to store the replica of the content related to the storage request, the control unit 21 determines the content evaluation value related to the storage request and the content already stored in the content storage area. If the evaluation value of the content related to the storage request is large, the replica of the content related to the storage request is stored after deleting the replica of the content having the smallest evaluation value. .

  Further, the control unit 21 determines whether or not there is related content associated with the new content related to the storage request by referring to the related content information included in the storage request message, for example. If it is determined that there is a content holding node storing a replica of the related content. In such a search, DHT routing using the above-described content ID as a key is used. That is, the control unit 21 acquires the index information returned from the root node by sending a content location inquiry message including the content ID of the related content to the root node of the related content. Such index information includes node information of one or a plurality of content holding nodes storing a replica of the related content.

  Then, the control unit 21 transmits a content storage request message indicating a storage request for a new content replica related to the storage request, to one or a plurality of content holding nodes searched by acquiring the index information. When the content storage node permits storage of new content related to the storage request, the control unit 21 transmits a replica of the new content related to the storage request to the content holding node. As a result, the new content replica can be stored in advance in the node Nn (node Nn storing the related content replica) that is likely to use (for example, view) the new content.

  FIG. 4 is a diagram illustrating how new content is stored. As illustrated in FIG. 4, the node N1 that has acquired a new content replica from the content providing server SA obtains index information from the root node of the related content associated with the new content, and obtains the related content replica. The new content replica is provided to the stored nodes N4 and N7.

  By the way, when a plurality of related contents are associated with the new content related to the storage request, the control unit 21 searches the content holding node storing the replica for each related content, and each searched content The content storage request message is transmitted to the holding node. According to this, it is possible to increase the number of nodes Nn for storing new content replicas in advance.

  Alternatively, the control unit 21 preferentially selects any one related content (for example, the first related content with the highest ranking) based on the rank information previously given to each related content, and the selection The content holding node storing the replica of the related content is searched, and the content storage request message is transmitted to the searched content holding node. According to this, it is possible to preferentially store the replica in the node Nn that is highly likely to use new content.

  The control unit 21 then selects any other related content (for example, the next ranking) after a predetermined time has elapsed since the transmission of the content storage request message to the content holding node storing the selected one related content replica. 2), the content holding node storing the replica of the selected related content is searched, and the content storage request message is transmitted to the searched content holding node.

  When a plurality of related contents are associated with the new content related to the storage request, the control unit 21 searches a plurality of content holding nodes storing the replica for each related content, and the search is performed. A content holding node that stores a replica of two or more related contents (for example, all related contents) is selected from the plurality of content holding nodes, and the content storage request message is sent to the selected content holding node. You may comprise so that it may transmit. According to this, it is possible to preferentially store the replica in the node Nn that is highly likely to use new content. That is, a node Nn that stores more replicas of related content associated with new content is more likely to use the new content than other nodes Nn.

[ 4. Operation of Content Distributed Storage System S ]
Next, the operation of the distributed content storage system S will be described with reference to FIGS.

  FIG. 5 is a flowchart showing processing in the control unit 11 of the content providing server SA. FIG. 6 is a flowchart showing processing in the control unit 21 of the node Nn, and FIG. 7 is a flowchart showing details of the content storage processing in step S15 in FIG. FIG. 8 is a flowchart showing details of the content storage processing to the related content holding node in step S162 in FIG. 7 or step S174 in FIG. 9, and FIG. 9 shows the content storage request processing in step S17 in FIG. It is a flowchart which shows a detail.

  The process in FIG. 5 is started in accordance with an instruction from the administrator when new content is input to the content distributed storage system S, for example.

  When FIG. 5 is started, first, the control unit 11 of the content providing server SA selects a predetermined number of new contents to be input from the contents registered in the content information list (step S1).

  Next, the control unit 11 randomly selects, for example, a plurality of nodes Nn that are new content input destinations from among the nodes Nn participating in the distributed content storage system S, and obtains node information of the nodes Nn. (Step S2).

  Next, the control unit 11 identifies one of the selected nodes Nn (step S3), establishes a connection with the node Nn based on the identified node information of the node Nn, and selects the content to be input. A save request message including information such as the content ID, evaluation value, release date, related content information, and size is transmitted to the node Nn (step S4).

  When a plurality of new contents are selected, information such as content ID, evaluation value, release date, related content information, and size of each content is included in the storage request message.

  Next, when receiving a reply message in response to the transmitted storage request message (step S5: YES), the control unit 11 determines whether or not the reply message is a storage permission message (whether or not storage is permitted) ( Step S6).

  When the reply message is a storage permission message (step S6: YES), the control unit 11 acquires a replica of the content to be input from the storage unit, and sends the replica to the node Nn that is the transmission source of the reply message. (Step S7), and the process proceeds to step S8. On the other hand, if the reply message is not a storage permission message (step S6: NO), that is, if the reply message is a storage rejection message, the control unit 11 proceeds to step S8 without transmitting a replica of the content.

  In step S8, it is determined whether or not all the nodes Nn selected in step S2 have been identified in step S3. If they have not been identified (step S8: NO), the control unit 11 performs step S3. Returning to the above, a node Nn that has not yet been identified is identified, and the same processing as described above is performed. On the other hand, when all the nodes Nn selected in step S2 have been identified (step S8: YES), the process ends.

  Note that the content shown in FIG. 5 may be configured to be executed at predetermined intervals until the release date and time arrives.

  Further, in the above processing, when the reply message is a storage permission message, the replica of the content to be input is configured to be transmitted to the node Nn that is the transmission source of the reply message. You may comprise so that it may transmit with respect to the said node Nn with a request message.

  Next, the process of FIG. 6 is started when the power is turned on at the node Nn. First, the control unit 21 performs a participation process (step S11). In the participation process, the control unit 21 establishes a connection with the contact node and transmits a participation message to the contact node. Then, when receiving the reply message returned from the contact node or the like, the control unit 21 generates a DHT routing table using the node information or the like included in each reply message.

  Next, the control unit 21 determines whether or not there is a power-off command (step S12). When there is no power-off command (step S12: NO), the control unit 21 proceeds to step S13, and when the power-off command is received. (Step S12: YES) After the withdrawal process is performed, the process of FIG. 6 is terminated.

  In step S13, the control unit 21 determines whether or not a storage request message has been received from the content providing server SA or the content holding node. If received (step S13: YES), the control unit 21 proceeds to step S14 and receives it. If not (NO in step S13), the process proceeds to step S16. Information such as content ID, evaluation value, release date, related content information, and size included in the received storage request message is temporarily stored in the RAM.

  In step S <b> 14, the control unit 21 determines whether or not a new content replica related to the storage request indicated in the received storage request message is already stored in the storage unit 22. This is determined, for example, based on whether or not the content ID included in the received storage request message is registered in the content information list.

  When the content replica related to the save request indicated in the save request message is already stored in the storage unit 22 (step S14: YES), the control unit 21 proceeds to step S16 and is not stored. (Step S14: NO), the process proceeds to Step S15.

  In step S15, the control unit 21 performs content storage processing (FIG. 7). In this content storage process, as shown in FIG. 7, first, the control unit 21 reduces the evaluation value of the content related to the storage request to, for example, ½ (one content is duplicated and becomes two. The purpose of dividing the evaluation value) is to recognize the free capacity (for example, 5 gigabytes) of the content storage area in the storage unit 22, and whether or not the content storage area has a free capacity equal to or larger than the size of the content related to the storage request. Is determined (step S152). If there is no free space (step S152: NO), the process proceeds to step S153. If there is free space (step S152: YES), the process proceeds to step S155.

  In step S153, the control unit 21 obtains the evaluation value of the content related to the storage request (the evaluation value reduced to ½ immediately before step S152) and the evaluation value of the content already stored in the content storage area. A comparison is made to determine whether there is a stored content smaller than the content evaluation value related to the storage request. If there is a saved content smaller than the evaluation value of the content related to the save request (step S153: YES), the process proceeds to step S154, and if there is no such saved content (step S153: NO). ), The process proceeds to step S163.

  In step S154, the control unit 21 registers the content ID of the content having the smallest evaluation value in the content stored in the content storage area (the content for which the evaluation value comparison has been performed) in the deleted content list, and the deleted content list. In addition to the above-mentioned free space (for example, 5 gigabytes), the size of the content registered in (1) is recognized as a new free space, and the process returns to step S152 to perform the same processing as above. In this case, the evaluation value of the content registered in the deleted content list is not compared in step S153.

  In step S155, the control unit 21 deletes the replica of the content registered in the deleted content list from the content storage area (if the content is not registered in the deleted content list, skips the processing), and Information such as content ID, evaluation value, release date, related content information, and size is deleted from the content information list.

  Next, the control unit 21 transmits a reply message as a storage permission message to the content providing server SA or content holding node that is the transmission source of the storage request message (step S156), and the content providing server SA or content holding is sent. A replica of the content related to the storage request transmitted from the node is received and stored in a content storage area in the storage unit 22 (step S157).

  Next, the control unit 21 stores the evaluation value of the stored content (evaluation value reduced to ½ immediately before step S152), the content ID stored in the RAM, the publication date, related content information, and Information such as size is newly registered in the content information list (step S158).

  Next, the control unit 21 calculates the storage request start date and time of the stored content, and registers the calculated storage request start date and time and the content ID of the content in the storage request content list in association with each other (step S159). This save request start date and time is a scheduled date and time when the node Nn transmits the save request message to another node Nn. For example, the storage request start date / time is the date / time obtained by subtracting the time from the current date / time to the publication date / time of the content (public preparation period) by the evaluation value of the content and adding the value obtained by the division to the current date / time. is there. In other words, the higher the content evaluation value, the shorter the period in which this date / time arrives (for details, see, for example, JP 2007-34630 A).

  Next, the control unit 21 sends a publish message including the content ID of the stored content and the node information of the own node toward the root node (step S160). As a result, the publish message arrives at the root node by DHT routing as described above, and index information including a set of node information and content ID included in the message is registered.

  If the storage request message includes information such as content ID, evaluation value, release date, related content information, and size of a plurality of new contents, each replica will be stored. For new content, a content storage request process to the related content holding node in step S162 described later is performed.

  Next, the control unit 21 refers to the related content information of the stored content and determines whether there is related content associated therewith (step S161). If there is no related content (step S161). : NO), the process returns to the process of FIG. 6, and if there is related content (step S161: YES), the process proceeds to step S162.

  On the other hand, in step S163, the control unit 21 transmits a reply message as a storage rejection message to the content providing server SA or content holding node that is the transmission source of the storage request message.

  In the content storage request processing to the related content holding node in step S162, as shown in FIG. 8, the control unit 21 stores the replica of the related content associated with the content stored in step S157. It is determined whether there is a related content holding node list in which node information of holding nodes (hereinafter referred to as “related content holding nodes”) is described (step S1621). If there is a related content storage node list (if it has already been created or acquired with a replica from another node Nn) (step S1621: YES), the related content storage node list is stored in the storage unit 22. (Step S1622), the process proceeds to step S1625, and if there is no related content storage node list (step S1621: NO), the process proceeds to step S1623.

  In step S1623, the control unit 21 performs a related content holding node search process. In such a search process, for example, the control unit 21 sends a content location inquiry message including the content ID of the related content associated with the content stored in step S157 and the node information of the own node to the root node. . As a result, the content location inquiry message arrives at the root node by DHT routing as described above, and the root node obtains index information corresponding to the content ID included therein from the index cache, and uses this as search result information. , A response is made to the node Nn that is the transmission source of the content location inquiry message. In the index information, node information of a related content holding node that stores a replica of the related content is described.

  Here, when a plurality of related contents are associated with the content stored in step S157, as described above, the related content holding node of each related content is searched, and any one related content (for example, There is a method of searching for a related content holding node of the highest-ranked related content), and the user can arbitrarily set which method is adopted. In the method of searching for the related content holding node of each related content, a content location inquiry message is sent to the root node of each related content, and index information as search result information is obtained from each root node. Become.

  Thus, when the control unit 21 acquires the index information as the search result information returned from the root node, the control unit 21 creates a related content holding node list based on the index information (step S1624). In the related content holding node list, the node information of the related content holding node described in the index information is described (registered), and the content ID of the corresponding related content is given. When index information of a plurality of related contents is obtained, a related content holding node list is created for each related content.

  Next, the control unit 21 selects one or a plurality of related content holding nodes that are the storage request destinations of the content stored in step S157 from the acquired or created related content holding node list, for example, in the order of random or registered numbers. (Step S1625).

  Here, when the related content holding node list of each related content is created by the method of searching the related content holding node of each related content, for example, one by one from the related content holding node list of each related content. A content holding node is selected.

  Alternatively, in this case, a related content holding node in which node information is described in both of the related content holding node lists of the related content is selected. For example, if there is a related content holding node list of related content A, a related content holding node list of related content B, and a related content holding node list of related content C, they are described in all the related content holding node lists. Related content holding nodes (that is, related content holding nodes storing replicas of the related content A, B, and C) are selected. Alternatively, related content holding nodes described in any two related content holding node lists are selected.

  Then, the control unit 21 establishes connection with the related content holding node based on the node information of the selected related content holding node, and the content ID, evaluation value, publication date and time of the content stored in step S157, A save request message including related content information and information such as size is transmitted to the related content holding node (step S1626). If a plurality of related content holding nodes are selected in step S1625, a save request message is transmitted to each related content holding node.

  Next, the control unit 21 deletes the node information of the selected related content holding node from the related content holding node list (step S1627). This is to prevent redundant selection of related content holding nodes in later processing.

  Next, when the control unit 21 receives a reply message to the saved storage request message (step S1628: YES), it determines whether or not the reply message is a storage permission message (step S1629).

  When the reply message is a storage permission message (step S1629: YES), the control unit 21 acquires a replica of the content related to the storage request (that is, stored in step S157) from the storage unit 22, and the replica Is transmitted to the related content holding node that is the transmission source of the reply message (step S1630), and the process proceeds to step S1631. Here, the control unit 21 selects a part (for example, 40 in ascending order of registration number) of node information of a plurality (for example, 100) of related content holding nodes described in the related content holding node list related to the storage request. And the related content holding node list including the divided node information is transmitted together with the replica to the related content holding node that is the transmission source of the reply message. As a result, the related content holding node storing the replica need not perform the related content holding node search process (step S1623), and the related content holding is the same (duplicate) among the plurality of nodes Nn. It is possible to avoid selecting a node. When there is a related content holding node list of a plurality of related contents, for example, for each related content holding node list, a part of node information is divided, and each related content holding node list including each divided node information is It will be transmitted with the replica.

  On the other hand, if the reply message is not a storage permission message (step S1629: NO), that is, if it is a storage rejection message, the control unit 21 proceeds to step S1632 without transmitting a replica of the content.

  In step S1631, the control unit 21 updates (e.g., reduces to 1/2) the evaluation value of the content replica related to the storage request (that is, stored in step S157), and proceeds to step S1632.

  In step S1632, the control unit 21 determines whether there is a related content holding node that does not return a reply message to the storage request message. If there is a related content holding node (step S1632: YES). Returning to step S1628, the same processing as described above is performed. On the other hand, if there are replies of reply messages from all the related content holding nodes to which the save request message has been transmitted (step S1632: NO), the process proceeds to step S1633.

  In step S1633, the control unit 21 determines whether or not the node information is still described in the related content holding list. If the node information is not described (step S1633: NO), the control unit 21 applies the content to the storage request. The association of the related content is released (step S1634), and the process returns to the process of FIG. 7, and if it is described (step S1633: YES), the process returns to the process of FIG. When there is a related content holding node list for each related content, the process of step S1633 is performed for each related content holding node list.

  Returning to the processing of FIG. 6, in step S <b> 16, the control unit 21 refers to the storage request content list, determines whether there is content whose storage request start date and time registered here has passed the current date and time, and stores the content. If there is a content whose request start date and time has passed the current date and time (step S16: YES), the process proceeds to step S17, and if not (step S16: NO), the process proceeds to step S18.

  In step S17, the control unit 21 performs content storage request processing (FIG. 9). In this content storage request process, as shown in FIG. 9, the control unit 21 first refers to the content information list, and the disclosure date and time of the content whose storage request start date and time has passed the current date and time have passed the current date and time. It is determined whether or not (step S171).

  If the current date / time of the content has not passed (step S171: NO), the control unit 21 sets the content as a storage request target and proceeds to step S172. Step S171: YES), the process returns to the process of FIG.

  In step S172, the control unit 21 updates the storage request start date and time of the content registered in the storage request content list. For example, the control unit 21 starts the next storage request obtained by subtracting the time from the current date and time to the disclosure date and time of the content with the evaluation value of the content and adding the value obtained by the division to the current date and time. The storage request start date and time registered in the storage request content list is updated (overwrite registration) according to the date and time.

  Next, the control unit 21 refers to the related content information of the content related to the storage request and determines whether there is related content associated therewith (step S173). (S173: YES), the process proceeds to step S174, and if there is no related content (step S173: NO), the process proceeds to step S175.

  In the content storage request processing to the related content holding node in step S174, the above-described processing of FIG. 8 is performed. If there is a plurality of contents whose storage request start date and time has passed the current date and time, a content storage request process to the related content holding node in step S174 described later is performed for each content.

  Here, only the related content holding node list of any one related content (for example, the first related content with the highest ranking) among the related content related to the content is created, and When there is no node information registered in the related content holding node list and the related content is not related, the processes in steps S1623 and S1624 described above are performed, and the next related content (for example, the highest ranking) is performed. The related content holding node list of the second related content) is created. Note that the processing of S1625 to S1634 in FIG. 8 is as described above, and thus description thereof is omitted.

  On the other hand, in step S175 of FIG. 9, the control unit 21 selects, for example, one other node Nn as a storage request destination at random (excluding the node Nn selected in the past), and acquires the node information of the node Nn. To do. For example, the node Nn that is the save request destination is selected from the nodes Nn whose node information is stored in the index cache area. Alternatively, if node information of a content holding node that has provided a replica of another content in the past is stored (if it remains in the log information), a node Nn that is a storage request destination is selected from the node information.

  Next, the control unit 21 establishes a connection with the node Nn based on the node information of the selected node Nn, and the content ID, evaluation value, release date, related content information, size, etc. of the content related to the storage request. Is sent to the node Nn (step S176).

  Next, when the control unit 21 receives a return message for the transmitted save request message (step S177: YES), it determines whether or not the return message is a save permission message (step S178).

  When the reply message is a save permission message (step S178: YES), the control unit 21 acquires a replica of the content related to the save request from the storage unit 22, and sends the replica to the node Nn that is the source of the reply message. In step S179, the process proceeds to step S180. On the other hand, if the reply message is not a storage permission message (step S178: NO), that is, if it is a storage rejection message, the control unit 21 returns to step S175 without transmitting the replica of the content, and receives another message. The node Nn is selected, and the same processing as described above is performed (for example, when rejected from a certain number of notes Nn, the processing returns to the processing in FIG. 6).

  In step S180, the control unit 21 updates (e.g., reduces to 1/2) the content evaluation value related to the storage request registered in the content information list, and returns to the processing of FIG.

  Next, in the other processing in step S18 of FIG. 6, the control unit 21 receives the other message (for example, publish message, content location inquiry message, content transmission request message, etc.), according to the user instruction. A content reproduction process, a content acquisition process based on a user instruction, and the like are performed, but these processes are well-known and will not be described in detail.

  In the processing of FIG. 6, when the reply message is a save permission message, the replica of the content related to the save request is transmitted to the node Nn that is the source of the reply message. May be transmitted to the node Nn together with the save request message.

  Further, in the above processing, when the content publication date / time has passed the current date / time (step S171: YES), the content storage request message is not transmitted to other nodes Nn. However, even after the current date and time have elapsed, the processing in steps S173 to S180 may be performed at predetermined time intervals.

  As described above, according to the embodiment, when the node Nn downloads and stores a content replica related to a new content replica storage request from the content providing server SA or the content holding node, the storage request It is determined whether there is related content associated with the related content. If it is determined that there is related content, a related content holding node storing a replica of the related content is searched. The node Nn is configured to transmit a content storage request message indicating a storage request for a replica of the content related to the storage request to the searched related content holding node, so that the new content is used ( For example, a replica of the new content can be stored (pre-cached) in advance in a related content holding node of a user who is likely to view), and access concentration to the content holding node storing the replica is concentrated. And the communication line can be prevented from being congested by downloading (the network can be transmitted in a time zone where the network is not relatively congested). In addition, the response of the own node can be improved.

  When a plurality of related contents are associated with the new content related to the storage request, the node Nn searches the related content holding node storing the replica for each related content, and searches each related content If the content storage request message is transmitted to the content holding node, the number of nodes Nn for storing new content replicas in advance can be increased.

  In addition, when a plurality of related contents are associated with the new content related to the storage request, the node Nn determines one of the related contents (for example, rank) based on the rank information previously given to each related content. The first related content with the highest attachment) is preferentially selected, a related content holding node storing a replica of the selected related content is searched, and the content storage is performed for the searched related content holding node If the request message is configured to be transmitted, the replica can be preferentially stored in the node Nn that has a high possibility of using new content.

  In addition, when a plurality of related contents are associated with the new content related to the storage request, the node Nn searches a plurality of related content holding nodes storing the replica for each related content, and the search is performed. Of the plurality of related content holding nodes, select a related content holding node that stores a replica of two or more related content (for example, all related content), and store the content for the selected related content holding node If the request message is configured to be transmitted, the replica can be preferentially stored in the node Nn that has a high possibility of using new content.

  In the above-described embodiment, for example, there are two or more new contents requested to be saved at the same time (for example, contents having the same or close release date), and the same related contents are associated with each new content. In this case, each of the two or more new content replicas is stored in the related content holding node storing the related content replica. From the viewpoint of content distribution, a content storage resource (for example, a hard disk) Etc.) is also not preferable. Therefore, in such a case, it is desirable for the content providing server SA or the node Nn to perform a duplication prevention process so that related content does not overlap among new content. For example, the content providing server SA or the node Nn associates the same related content before transmitting the save request message (for example, immediately before step S3, immediately before step S162, immediately before step S174). Then, a process of releasing (including ignoring) the association of the same related content from any new content among the new content is performed. As a result, a plurality of new content replicas can be more efficiently distributed and the storage capacity of the content storage area can be saved.

  FIG. 10 is a conceptual diagram illustrating an example of associating related content with each new content. In the example of FIG. 10, each related content associated with each new content W, X, Y, Z is given rank information indicating the above-described ranking, and each new content W, X, Priority information indicating the priority order of new contents is also given to Y and Z.

  In this case, since the same related content A is associated with each of the new content W, X, and Y, the content providing server SA or the node Nn associates the related content A with the content W having a high priority. Maintain and release the association of the related content A to the content X, Y. Further, since the same related content E is associated with each of the new contents X and Y, the content providing server SA or the node Nn maintains the association of the related content E with the content X having a high priority, The association of the related content E with the content Y is released. In addition, the same related content B is associated with each of the new contents W and Z, but the related content B associated with the content W has the second rank information and the related content associated with the content Z. Since B is ranked first, the content providing server SA or the node Nn prioritizes the rank information over the priority information, maintains the association of the related content B to the content Z, and the related content to the content W. Release the association of B.

  By such processing, for example, the new content W includes a related content holding node storing a replica of the related content A, a related content holding node storing a replica of the related content C, and a replica of the related content D. Is stored in advance (pre-cache) with the related content holding node storing the content. Further, the new content X is stored (pre-cached) in advance in a related content holding node storing a replica of the related content E and a related content holding node storing a replica of the related content F. . Further, the new content Z is stored (pre-cached) in advance in a related content holding node storing a replica of the related content B and a related content holding node storing a replica of the related content G. .

  However, in this case, since the new content Y is not stored in any related content holding node, in order to avoid this, the same related content is selected from the new content having a large number of related content. It may be configured to cancel the association. For example, since the same related content A is associated with each of the new contents W, X, and Y, the association of the related content A with the content Y with the smallest number of related contents is maintained, and the number of related contents The association of the related content A to the content W, X having more than the content Y is released. Thereby, a plurality of new content replicas can be more efficiently distributed.

  Further, in the above embodiment, it may be configured such that not all data of a replica of a new content is downloaded, but only a part of data at the beginning of the replica is downloaded. In this case, it suffices to download the remaining partial data (data other than the first data) in parallel with the reproduction of the first data, thereby saving the storage capacity of the content storage area and increasing the number of contents to be pre-cached. As a result, the response can be improved.

  In addition, although the content distributed storage system S in the said embodiment was demonstrated on the assumption that it was formed by the algorithm using DHT, this invention is not limited to this.

It is a figure which shows an example of the connection aspect of each node apparatus in the content distributed storage system which concerns on this embodiment. It is a figure which shows the example of a schematic structure of content provision server SA. It is a figure which shows the example of an outline structure of the node Nn. It is a figure which shows a mode that a new content is preserve | saved. It is a flowchart which shows the process in the control part 11 of content provision server SA. It is a flowchart which shows the process in the control part 21 of the node Nn. It is a flowchart which shows the detail of the content preservation | save process in step S15 of FIG. It is a flowchart which shows the detail of the content preservation | save process to the related content holding node in step S162 of FIG. 7, or step S174 in FIG. It is a flowchart which shows the detail of the content preservation | save request process in step S17 of FIG. It is a conceptual diagram which shows an example of the correlation of the related content to each new content.

Explanation of symbols

8 Network 9 Overlay Network 11 Control Unit 12 Storage Unit 13 Display Unit 14 Input Unit 15 Communication Unit 16 Bus 21 Control Unit 22 Storage Unit 23 Buffer Memory 24 Decoder Unit 25 Video Processing Unit 26 Display Unit 27 Audio Processing Unit 28 Speaker 29 Communication Unit 30 input unit 31 bus Nn node SA content providing server S content distributed storage system

Claims (12)

A distributed content storage system comprising a plurality of node devices that can communicate with each other via a network, wherein copy data of a plurality of contents is distributed and stored in a plurality of node devices, and the content is used between the node devices The node device in the distributed content storage system that is enabled,
Storage means having a storage area for storing the replicated data;
A storage request receiving means for receiving content storage request information indicating a storage request for new content copy data from another node device or a server device having copy data of all content;
Content storage means for acquiring copy data of the content related to the storage request from the other node device or the server device, and storing it in a storage area in the storage means;
Content determination means for determining whether or not there is related content that is associated in advance with the new content related to the storage request and is already available between the node devices;
If it is determined that there is related content associated with the new content, node search means for searching for another node device storing duplicate data of the related content;
Storage request transmission means for transmitting content storage request information indicating a storage request for the copy data of the new content to the other node device searched;
A node device comprising: The node device according to claim 1,
When a plurality of the related contents are associated with the new content, the node search means selects any one of the related contents based on rank information given in advance to each of the related contents, A node device that searches for another node device that stores copy data of the selected related content. The node device according to claim 2,
After a predetermined time has elapsed since transmission of the content storage request information to another node device storing the selected one related content, the node search means selects any other related content, and A node device that searches for another node device that stores duplicate data of the selected related content. The node device according to claim 1,
When a plurality of related contents are associated with the new content, the node search means searches for a plurality of other node devices storing duplicate data of the related contents, and the searched plurality of related contents Select another node device storing duplicate data of two or more of the related contents among other node devices,
The node device, wherein the storage request transmission unit transmits content storage request information indicating a storage request for the copy data of the new content to the other selected node device. The node device according to claim 1,
In the case where there are two or more new contents, when the same related contents are associated with each of the new contents, the association cancellation is performed to cancel the association of the same related contents from any of the new contents. A node device further comprising means. The node device according to claim 5, wherein
The node device is characterized in that the association canceling unit cancels the association of the same related content from the new content having the larger number of the related content items associated therewith. A distributed content storage system comprising a plurality of node devices that can communicate with each other via a network, wherein copy data of a plurality of contents is distributed and stored in a plurality of node devices, and the content is used between the node devices A server device that manages duplicate data of the content in a content distributed storage system that is enabled,
A node selection means for selecting any one of the plurality of node devices in the content distributed storage system;
Duplicate data of new content and information indicating related content that is associated with the new content in advance and is already available between the respective node devices, for the selected node device Related content information transmitting means for transmitting,
In the case where there are two or more new contents, and the same related contents are associated with each of the new contents, the information indicating the related contents is transmitted from any of the new contents before the information is transmitted. Disassociating means for canceling the association of the same related content;
A server device comprising: The server device according to claim 7,
The server is characterized in that the association release means releases the association of the same related content from the new content having a larger number of the related content associated therewith.   A node processing program for causing a computer to function as the node device according to any one of claims 1 to 6.   A server processing program for causing a computer to function as the server device according to claim 7 or 8. A distributed content storage system comprising a plurality of node devices that can communicate with each other via a network, wherein copy data of a plurality of contents is distributed and stored in a plurality of node devices, and the content is used between the node devices In the distributed content storage system that made possible,
The node device is
Storage means having a storage area for storing the replicated data;
A storage request receiving means for receiving content storage request information indicating a storage request for new content copy data from another node device or a server device having copy data of all content;
Content storage means for acquiring copy data of the content related to the storage request from the other node device or the server device, and storing the content in the storage area of the storage device;
Content determination means for determining whether or not there is related content that is associated in advance with the new content related to the storage request and is already available between the node devices;
If it is determined that there is related content associated with the new content, node search means for searching for another node device storing duplicate data of the related content;
Storage request transmission means for transmitting content storage request information indicating a storage request for the copy data of the new content to the other node device searched;
A content distributed storage system comprising: A distributed content storage system comprising a plurality of node devices that can communicate with each other via a network, wherein copy data of a plurality of contents is distributed and stored in a plurality of node devices, and the content is used between the node devices A content storage method in a distributed content storage system,
A storage request receiving step in which the node device receives content storage request information indicating a request to store new content copy data from another node device or a server device having copy data of all content;
A content storage step in which the node device acquires copy data of the content related to the storage request from the other node device or the server device and stores the copy data in a storage area for storing the copy data;
A content determination step of determining whether or not there is related content that is previously associated with the new content related to the storage request and is available between the node devices;
When it is determined that the node device has related content associated with the new content, a node search step of searching for another node device storing duplicate data of the related content;
A storage request transmission step in which the node device transmits content storage request information indicating a storage request for the copy data of the new content to the other node device searched;
The content storage method characterized by including.

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