JP5218356B2 - Information communication system, information communication method, support device, and information communication processing program - Google Patents

Description

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

  Conventionally, for example, a content distribution system using an edge server as disclosed in Patent Document 1 is known. In this system, an edge server capable of storing a large amount of content in advance is installed at a base where a terminal device used by a user is located. When the necessary content is stored in the edge server in the site, the terminal device directly acquires the content from the edge server. On the other hand, when the edge server does not store the required content, the edge server acquires content from a center server or other edge server outside the base, and transmits it to the terminal device. This avoids concentration of access to the center server device. In addition, the traffic on the line externally connected from the network in the base is reduced.

JP 2003-223378 A

  However, in a system using an edge server, content requests concentrate on the edge server when the number of terminal devices in the base increases. As a result, the load on the edge server increases and smooth content distribution is hindered.

  Therefore, the present invention has been made in view of the above points. An object of the present invention is to provide an information communication system, an information communication method, and the like that can reduce the load on a support device such as an edge server and can smoothly acquire content.

  In order to solve the above-described problem, the invention according to claim 1 is an information communication system in which a plurality of contents are transmitted and received between a plurality of node devices, and the information communication system includes a plurality of internal networks in an external network. Are connected to the same internal network, and a support device that is connected to the internal network and supports content acquisition by the node device for each internal network, the support device When the connection destination node device, which is the node device connected to the internal network of the connection destination, acquires content from any of the support devices or any of the node devices, the related content related to the content is displayed. The support device that is not connected to the internal network of the connection destination Related content acquisition means acquired from a non-connection-destination support device or a connection-destination node device that is the node device that is not connected to the internal network of the connection destination, and the related content acquired by the related content acquisition means Related content transmitting means for transmitting the content to at least one of the connection destination node devices, wherein the node device acquires content stored by the support device or another node device. And storing related content received by the related content receiving unit and receiving the related content transmitted from the connection destination support device that is the support device connected to the internal network of the connection destination. And storage means for .

  It is considered that the content related to the content acquired by the node device is relatively likely to be requested from the support device in the future among the content not yet acquired. According to the present invention, content related to content acquired by a certain node device is stored by any node device connected to the same internal network as the acquired node device. Therefore, when the node device that has acquired the content acquires content related to the content, it can be acquired from the node device connected to the same internal network. This avoids concentration of content requests on the support device. Therefore, the load on the support device can be reduced, and the content can be acquired smoothly by the node device.

  The invention according to claim 2 is the information communication system according to claim 1, wherein the content acquisition means of the node device acquires content from the other node device connected to the internal network of the connection destination, When the content cannot be acquired from the other node device, the content is acquired from the unconnected support device or the unconnected node device.

  According to the present invention, when content required by a node device is stored in another node device connected to the same internal network, the content is acquired from the other node device in preference to the support device. Is done. Therefore, the load on the support device can be reduced. The content transmission load is distributed to a plurality of node devices connected to the same internal network. Therefore, content acquisition by the node device can be performed smoothly.

  According to a third aspect of the present invention, in the information communication system according to the second aspect, the content acquisition means of the node device acquires content from the other node device connected to the internal network of the connection destination. If the content cannot be acquired from the connection destination support device when the content cannot be acquired from the connection destination support device, the content can be acquired from the connection device outside the connection or the node device outside the connection. Features.

  According to the present invention, when the content required by the node device is stored in the connection destination support device, the content from the connection destination support device has priority over the non-connection destination support device and the non-connection destination node device. Is acquired. Therefore, the traffic on the line connected from the internal network to the external network is reduced, and the content can be acquired efficiently.

  According to a fourth aspect of the present invention, in the information communication system according to any one of the first to third aspects, the related content acquisition unit of the support device is configured such that the connection destination node device is the support device outside the connection destination. Alternatively, when the content is acquired from the node device outside the connection destination, the related content is acquired.

  According to the present invention, even when content required by a node device is not stored in another node device or support device connected to the same internal network, content related to the content is stored in the same internal It can be stored in any node device connected to the network.

  According to a fifth aspect of the present invention, in the information communication system according to the fourth aspect, the content acquisition means of the node device sends request information required for requesting the content via the connection destination support device. Request information transmitting means for transmitting to the non-connected support device or the non-connected node device, and the content transmitted from the non-connected support device or the non-connected node device via the connection support device Content receiving means, and the support device relays information transmitted and received between the connection destination node device and the connection destination outside support device or the connection destination outside node device, and Second storage means for storing content received from the non-connected support device or the non-connected node device by a relay means; Characterized in that it comprises.

  According to this invention, the content acquired by the node device connected to the same internal network can be stored in the support device.

  According to a sixth aspect of the present invention, in the information communication system according to the fifth aspect, the relay unit of the support device stores content in the second storage unit when the request information is received. Is characterized in that the content stored in the second storage means is transmitted to the connection destination node device that is the transmission source of the request information without relaying the request information.

  According to the present invention, when the support device stores the content requested from the node device connected to the same internal network, the support device needs to acquire the content from the unconnected support device and the unconnected node device. There is no. Therefore, content acquisition by the node device can be performed in a short time.

  According to a seventh aspect of the present invention, in the information communication system according to the fifth or sixth aspect, the relay unit of the support device stores the content in the second storage unit when receiving the request information. If not, the request information is relayed, the related content acquisition means of the support device acquires the related content related to the content received by the relay means, and the second storage means The related content acquired by the related content acquisition means is stored.

  According to the present invention, content that is considered to be relatively likely to be requested from the node device is stored in the support device, so that the utilization efficiency of the storage means of the support device can be improved.

  The invention according to claim 8 is the information communication system according to any one of claims 1 to 7, wherein the use bandwidth of information communication by the support device is equal to or less than a predetermined bandwidth, or When the processing load of the support device is equal to or lower than a predetermined load, the related content acquisition unit of the support device acquires the related content, and the related content transmission unit of the support device transmits the related content. Features.

  According to the present invention, when there is a margin in the communication bandwidth of the support device and the load on the CPU, the related device acquires and transmits related content. Thereby, it can prevent that the load of the support apparatus at the time of acquisition of a related content becomes high. Therefore, content acquisition by the node device can be performed smoothly.

  The invention according to claim 9 is an information communication method in an information communication system in which a plurality of contents are transmitted and received between a plurality of node devices, wherein the information communication system includes a plurality of internal networks connected to an external network, A plurality of node devices connected to the same internal network and a support device that supports the content acquisition by the node device connected to the internal network are provided for each internal network, and the node device includes the support device. Or a content acquisition step of acquiring content stored by another node device, and the support device is related to the content acquired by the connection destination node device that is the node device connected to the connection destination internal network Related content to connect to the internal network A related content acquisition step of acquiring from a non-connected support device that is not connected to the internal network, or a non-connected node device that is not connected to the internal network of the connection destination, and the support A related content transmission step in which the device transmits the related content acquired in the related content acquisition step to at least one of the connection destination node devices; and the node device connects to the internal network of the connection destination. A related content receiving step for receiving the related content transmitted from the connection destination support device which is the support device; and a storage step for storing the related content received by the node device in the related content receiving step. It is characterized by having.

  The invention according to claim 10 is an information communication system in which a plurality of contents are transmitted and received between a plurality of node devices, and is a support device that supports acquisition of contents by the node devices, wherein the information communication system A plurality of internal networks are connected to the network, and each of the internal networks includes a plurality of node devices connected to the same internal network and the support device connected to the internal network. When the connection destination node device that is the node device connected to the internal network acquires content from any of the support devices or any of the node devices, the related content related to the content is The support device not connected to the internal network A related content acquisition unit that acquires from a connection destination external device that is a connection device outside the connection destination or a node device that is not connected to the internal network of the connection destination, and the related content acquired by the related content acquisition unit And related content transmission means for transmitting content to at least one of the connection-destination node devices.

  The invention according to claim 11 is an information communication processing program in an information communication system in which a plurality of contents are transmitted / received between a plurality of node devices, wherein the information communication system has a plurality of internal networks connected to an external network. A plurality of node devices connected to the same internal network and a support device connected to the internal network and supporting content acquisition by the node device for each internal network, the computer included in the support device In addition, when the connection destination node device, which is the node device connected to the connection destination internal network, acquires content from any of the support devices or any of the node devices, related content related to the content Connected to the internal network A related content acquisition step of acquiring from a non-connected support device that is not a support device or a non-connection-target node device that is a node device that is not connected to the internal network of a connection destination, and the related content acquisition means A related content transmission step of transmitting the acquired related content to at least one of the connection destination node devices.

  According to the present invention, when a node device that has acquired content acquires content related to the content, it can be acquired from the node device connected to the same internal network. This avoids concentration of content requests on the support device. Therefore, the load on the support device can be reduced, and the content can be acquired smoothly by the node device.

It is a figure showing an example of outline composition of contents distribution system S concerning one embodiment. It is a figure which shows the construction example of P2P network PW in the content delivery system S which concerns on one Embodiment. It is the conceptual diagram which showed an example of the mode in case the user terminal Tm-n acquires a content in the content delivery system S which concerns on one Embodiment. It is the conceptual diagram which showed an example of the mode in case the user terminal Tm-n acquires a content in the content delivery system S which concerns on one Embodiment. It is a figure which shows an example of the correlation of the content described in the correlation definition file. It is a figure which shows the outline | summary structural example of input server ST. It is a figure which shows the example of a schematic structure of edge server SEm. It is a figure which shows the example of a schematic structure of user terminal Tm-n. It is a flowchart which shows the process example in the control part 41 of user terminal Tm-n which concerns on one Embodiment. It is a flowchart which shows the process example in the control part 41 of user terminal Tm-n which concerns on one Embodiment. It is a flowchart which shows the process example in the control part 21 of edge server SEm which concerns on one Embodiment. It is a flowchart which shows the process example in the control part 21 of edge server SEm which concerns on one Embodiment. It is a figure which shows an example of the content registered into index information. It is a flowchart which shows the process example of the content acquisition process in the control part 41 of user terminal Tm-n which concerns on one Embodiment. It is a figure which shows the construction example of P2P network PW2 and base P2P network PLm in the content delivery system S which concerns on one Embodiment. It is the conceptual diagram which showed an example of the mode in case the user terminal Tm-n acquires a content in the content delivery system S which concerns on one Embodiment.

  Hereinafter, embodiments of the present 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 distribution system.

[1. First Embodiment]
[1.1 Outline of content distribution system]
First, the schematic configuration of the content distribution system according to the first embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a diagram illustrating a schematic configuration example of a content distribution system S according to the present embodiment.

  As shown in FIG. 1, in the content distribution system S, a distribution center network NS and a plurality of base networks NLm (m = 1, 2, 3,...) Are connected to a network NW. This network NW, distribution center network NS, and each base network NLm are real-world communication networks. The network NW is an example of an external network. The base network NLm is an example of an internal network.

  The network NW is a network for interconnecting the distribution center network NS and each base network NLm. The network NW is, for example, the Internet or a WAN (Wide Area Network). The network NW includes, for example, IX (Internet eXchange), ISP (Internet Service Provider), DSL (Digital Subscriber Line) line provider apparatus, FTTH (Fiber To The Home) line provider apparatus, communication line, etc. Is built by. The network NW may be a network dedicated to the content distribution system S.

  The distribution center network NS is a network constructed in the site of the distribution center. This distribution center network NS is constructed by, for example, a LAN (Local Area Network) or the like.

  The distribution center network NS is connected to server devices such as the input server ST, the management server SM, and the portal server SP, and the management terminal MT. Further, a firewall FW that interconnects the distribution center network NS and the network NW is connected to the distribution center network NS via a communication line LS.

  Each base network NLm is a network constructed in the site of the base m. The bases include, for example, a company, a school, a hospital, and a cram school. This base network NLm is constructed by a LAN or the like, for example. Alternatively, the base network NLm may be a network constructed by interconnecting a plurality of LANs. In this case, the plurality of LANs are connected via a network device such as a router. An example of a network in which a plurality of LANs are interconnected is CAN (Campus Area Network).

  In addition, a plurality of user terminals Tm-n (n = 1, 2, 3...) And an edge server SEm are connected to each base network NLm. Furthermore, a firewall FW or a broadband router BR that interconnects the distribution center network NS and the network NW is connected to each base network via a communication line Lm. Which of the firewall FW and the broadband router BR is installed at the base is arbitrarily determined for each base. The user terminal Tm-n is an example of a node device. The edge server SEm is an example of a support device.

  In the content distribution system S having such a configuration, the functional outline of each device as a component is as follows.

  The input server ST is a server device that inputs content data to a P2P network PW described later. Here, the input of content data refers to placing content data in a state where it can be acquired from the edge server SEm and the user terminal Tm-n. The content data is referred to as “content”.

  The portal server SP transmits a web page to the user terminal Tm-n in response to a request from the user terminal Tm-n. The Web page transmitted by the portal server SP constitutes a Web site that distributes moving image data as an example of content.

  The management server SM provides a web application for managing the content to be distributed to the management terminal MT. That is, the management server SM transmits a web page for managing content to the management terminal MT.

  The user terminal Tm-n is a terminal device used by a user at the base m. The user terminal Tm-n acquires a Web page from a Web server such as the portal server SP, and displays the acquired Web page on the screen. Further, the user terminal Tm-n acquires and stores content from other user terminals Tm-n, the edge server SEm, or the input server ST. Basically, the user terminal Tm-n can acquire content from the user terminal Tm-n and the edge server SEm installed in any base m. However, the user terminal Tm-n acquires the content via the edge server SEm in the same base when acquiring the content from the edge server SEm at another base or the user terminal Tm-n at another base. Furthermore, the user terminal Tm-n reproduces content such as moving image data.

  At least one edge server SEm is installed at each base m. The edge server SEm supports content acquisition by the terminal Tm-n connected to the same base m. Specifically, the edge server SEm relays a message exchanged between the user terminal Tm-n in the same site and the edge server SEm at another site or the user terminal Tm-n at another site. Further, the edge server SEm acquires content related to the content acquired by the user terminal Tm-n in the same base from the other edge server SEm, the user terminal Tm-n of the other base, or the input server ST. Then, the edge server SEm stores the acquired content in any user terminal Tm-n in the same base. Note that content related to a certain content is referred to as “related content” of the certain content. Basically, the edge server SEm can acquire content from the user terminal Tm-n and the edge server SEm installed at any base m. Further, the edge server SEm stores the acquired content.

  Here, the user terminal Tm-n or the edge server SEm in the same base is the user terminal Tm-n or the edge server SEm connected to the base network NLm to which the user terminal Tm-n that acquires content is connected. Further, the user terminal Tm-n or the edge server SEm at another base is the user terminal Tm-n or the edge server SEm connected to the base network NLm other than the base network NLm to which the user terminal Tm-n that acquires content is connected. is there. The user terminal Tm-n in the same base is an example of a connection destination node device. The edge server SEm in the same base is an example of a connection destination support device. Further, the edge server SEm at another base is an example of a support device outside the connection destination. In addition, the user terminal Tm-n at another base is an example of a node device outside the connection destination.

[1.2 Overview of peer-to-peer network]
Next, an overview of a peer-to-peer network in the content distribution system S will be described with reference to FIG.

  FIG. 2 is a diagram illustrating a construction example of the P2P network PW in the content distribution system S according to the present embodiment.

  In the content distribution system S, a peer-to-peer network for content distribution is constructed. This peer-to-peer network is referred to as “P2P network PW”.

  As shown in FIG. 2, the P2P network PW is a logical overlay network built on a network formed by a network NW and a plurality of base networks NLm. The P2P network PW is a network formed by connecting any one of the user terminals Tm-n and the edge server SEm among the user terminals Tm-n and the edge server SEm constituting the content distribution system S. The input server ST may also be connected to the P2P network PW. Each base network NLm is connected to the network NW via the broadband router BR and the firewall FW. Therefore, the port forwarding is set in the broadband router BR and the firewall FW so that the user terminal Tm-n and the edge server SEm can communicate by the peer-to-peer method. For example, in the case of a broadband router BR, it is preferable to set port forwarding automatically using a UPnP (Universal Plug and Play) function or the like.

  In the following description, a device connected to the P2P network PW is referred to as a “node”. Devices corresponding to this node are the user terminal Tm-n and the edge server SEm. Alternatively, the user terminal Tm-n, the edge server SEm, and the input server ST correspond to nodes.

  The P2P network PW is realized by a specific algorithm, for example, an algorithm using a DHT (Distributed Hash Table). Each node connected to the content distribution system S is assigned a node ID, which is unique identification information having a predetermined number of digits.

  The node ID is, for example, a value obtained by hashing an IP address, a serial number, or a MAC address (Media Access Control address) individually assigned to each node using a common hash function. The node IDs are arranged in a distributed manner in the ID space. For example, SHA-1 or the like is used as the hash function. The hashed value has a bit length of 160 bits, for example. The node IDs are distributed in the ID space without being distributed. The node ID may be registered for each node by a system administrator, a user, or the like when setting up P2P software for connecting to the P2P network PW. The P2P network PW shown in FIG. 2 shows the ID space of the node ID as a ring. The position of each node shown in the ring-shaped ID space of FIG. 2 corresponds to each node ID.

  Connection to the P2P network PW is performed by a node not connected to the P2P network PW transmitting a participation request message indicating a participation request to the content distribution system to any connected node. This participation request message is an example of participation request information. Here, participation in the P2P network PW means that a node is connected to the P2P network PW and can acquire content from the P2P network PW. The arbitrary node is, for example, a contact node that is always connected to the P2P network PW. The contact node in the P2P network PW is, for example, the input server ST.

  Each node holds a routing table using DHT. This routing table defines various message transfer destinations on the content distribution system S. Specifically, a plurality of pieces of node information indicating addresses and the like of nodes that are appropriately separated in the ID space are registered in this routing table. This node information includes the node ID, IP address, and port number of the node.

  One node connected to the P2P network PW stores the minimum necessary node information as a routing table. By transferring various messages between the nodes, node information about nodes that do not store node information is acquired.

  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.

  The P2P network PW stores various content replicas having different contents distributed in a plurality of nodes in a predetermined file format. A replica can be used between the nodes. The original of each content is stored in the input server ST. For example, a content cache area of the edge server SE5 stores a movie content replica with the title XXX. On the other hand, the content cache area of the edge server SE3 stores a replica of the movie content whose title is YYY. In this way, the content is distributed and stored in a plurality of nodes. The content cache area is an area for storing and storing content. For example, the actual content cache area is allocated to a specific hard disk included in the node, or is allocated to a specific partition of the hard disk. The storage capacity of the content cache area of the edge server SEm is larger than the storage capacity of the content cache area of the user terminal Tm-n. As an example, the storage capacity of the content cache area of the edge server SEm is about 10 to 100 times the storage capacity of the content cache area of the user terminal Tm-n. When content cannot be stored in the content cache area, new content is stored. For example, the content is deleted from the content cache area in the oldest order. Whether the content is new or old is determined based on, for example, the use date of the content. Hereinafter, a node in which a content replica is stored is referred to as a “content holding node”. In the following description, the original content and the replica are referred to as content without particular distinction.

  Information such as a content name and content ID, which is unique identification information for each content, is added to each content described above. This content ID is generated, for example, by hashing the content name + an arbitrary numerical value with a hash function common to the case of obtaining the node ID. Alternatively, the system administrator may give a unique ID value for each content.

  The location of the content that is distributed and stored is stored as index information by a node or the like that manages (stores) the location of the content. Hereinafter, a node that manages (stores) the location of content is referred to as a “root node”. The index information includes a set of node information of the node that stores the content, content ID of the content, and the like. Such a root node is determined to be a node having a node ID closest to the content ID, for example. The node ID closest to the content ID is, for example, the node ID with the highest number of upper digits that match.

  For example, the index information about the content of the movie whose title is XXX is managed by the user terminal T3-1 that is the root node of the content. Further, for example, the index information about the content of the movie whose title is YYY is managed by the user terminal T3-3 that is the root node of the content.

  When a user of a certain node wants to acquire desired content, the node that desires acquisition of the content generates a message. Hereinafter, a node that the user desires to acquire content is referred to as a “user node”. This message is a content location inquiry message including the content ID of the content desired to be acquired, the IP address of the user node, the port number, and the like. The content location inquiry message is a message for searching for a content holding node. The content location inquiry message described above is sent to other nodes according to the DHT routing table acquired by the user node. That is, the user node sends a content location inquiry message toward the root node. As a result, the content location inquiry message finally arrives at the root node by DHT routing using the content ID as a key. The content location inquiry message is an example of request information.

  In each node, attribute information such as content ID of the content is described in the content catalog information. The content attribute information described in the content catalog information includes, for example, a content name, a content ID, a content publication start date and time, a publication end date and time, a valid / invalid flag, and the like. The valid / invalid flag is a flag indicating whether the content is valid or invalid. If this valid / invalid flag indicates invalid, the corresponding content is deleted from the content cache area.

  The content catalog information is distributed from the input server ST to all nodes, for example. The distribution of the content catalog information may be performed by, for example, DHT multicast (multicast message transfer processing) disclosed in Japanese Patent Application Laid-Open No. 2007-053662. Each node may acquire the content catalog information by accessing the input server ST periodically.

  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 has received the content location inquiry message obtains index information corresponding to the content ID included therein from the index information cache. The acquired index information is returned to the user node that is the transmission source of the content location inquiry message. The user node that has acquired the index information in this way can download (acquire) the content based on the index information. The user node accesses the content holding node based on the IP address and port number of the content holding node included in the index information. The user node can download the content from the accessed content holding node. The index information may include node information of a plurality of content holding nodes. In this case, the user node selects one content holding node from among the plurality of content holding nodes. The user node can connect to the selected content holding node and download the content.

  Note that the root node may transmit a content transmission request message to the content holding node indicated by the IP address and port number included in the index information. Thereby, the user node can also download the content from the content holding node. In addition, the user node can obtain 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.

  When the user node acquires and stores content from the content holding node, the stored user node generates a publish message. This publish message is a message for informing the root node that the content has been saved. The publish message includes the content ID of the content and node information of the node device that stores the content. The publish message is sent toward 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 message. Then, the root node receives the publish message. The root node stores index information including a set of node information and content ID included in the publish message in the index information cache area. Thus, the user node becomes a new content holding node that holds the content.

[1.3 Overview of content distribution]
Next, with reference to FIG. 3 to FIG. 5, an outline of the operation of the content distribution system S in the case of distributing content will be described.

  3 and 4 are conceptual diagrams illustrating an example of a situation where the user terminal Tm-n acquires content in the content distribution system S according to the present embodiment.

  When a certain user terminal Tm-n, for example, the user terminal T1-1 accesses the portal server SP, the Web page is received and displayed on the screen. Then, on the Web page displayed on the screen, the user requests playback of certain content, for example, content A. Then, the user terminal T1-1 searches for and acquires the location of the content A. Specifically, the user terminal T1-1 transmits a search request message by L2 (layer 2) broadcast (FIG. 3 (1)). Therefore, the search request message is transmitted to other user terminals Tm-n in the same base. This search request message includes the content ID of content A. Among the user terminals Tm-n that have received the search request message, for example, when the user terminal T1-5 stores the content A, the user terminal T1-5 transmits the content A to the user terminal T1-1. (FIG. 3 (2A)). The reason why the user terminal Tm-n in the same site is selected with the highest priority as the content acquisition destination is to reduce the load on the edge server SEm in the same site and to reduce the traffic on the communication line Lm. is there.

  When none of the other user terminals Tm-n connected to the base network NL1 stores the content A, the user terminal T1-1 cannot acquire the content A from the user terminals Tm-n in the same base. Therefore, the user terminal T1-1 transmits a content location inquiry message. Normally, the content location inquiry message is transmitted to other nodes according to the DHT routing table. However, in the present embodiment, the content location inquiry message is transmitted to the edge server SEm in the same base. That is, in this case, the content location inquiry message is transmitted to the edge server SE1 (FIG. 3 (2B)). As a result, the user terminal T1-1 relays the content location inquiry message using the edge server SE1 as a proxy. When the edge server SE1 stores the content A, the edge server SE1 transmits the content A to the user terminal T1-1 (FIG. 3 (3B)). In this case, the edge server SE1 does not need to relay the content location inquiry message.

  When the edge server SE1 does not store the content A, the edge server SE1 relays the received content location inquiry message. In this case, the edge server SE1 transmits a content location inquiry message to another node according to the routing table (FIG. 4 (3C)). This content location inquiry message is transferred to the user terminal T5-1, which is the root node, via the edge server SE6, for example.

  Receiving the content location inquiry message, the user terminal T5-1 transmits a search response message including the index information of the content A to the edge server SE1 (FIG. 4 (4C)). The edge server SE1 relays the received search response message to the user terminal T1-1 (FIG. 4 (5C)).

  The user terminal T1-1 selects a content holding node as an acquisition destination of the content A based on the index information included in the received search response message. The content holding node in this case is the edge server SEm at another base or the user terminal Tm-n at another base. When the user terminal T1-1 selects the content holding node, the user terminal T1-1 transmits a content request message. Usually, the content request message is sent directly to the content holding node. However, in the present embodiment, the content request message is transmitted to the edge server SEm in the same site. That is, in this case, the content request message is transmitted to the edge server SE1 (FIG. 4 (6C)). The edge server SE1 relays the received content request message. In this case, the edge server SE1 transmits a content request message to the content holding node selected by the user terminal T1-1, for example, the user terminal T4-3 (FIG. 4 (7C)).

  The user terminal T4-3 that has received the content request message transmits the content A to the edge server SE1 (FIG. 4 (8C)). At this time, the user terminal T4-3 actually transmits a content request response message including the content A. The edge server SE1 stores the content included in the received content request response message and relays the content request response message to the user terminal T1-1 (FIG. 4 (9C)).

  Further, the edge server SE1 acquires the related content of the content A, for example, the content B (FIG. 4 (10C)). The content acquisition method in this case is as described in the outline of the peer-to-peer network described above. The edge server SE1 stores the acquired content B and transmits the content B to any user terminal Tm-n, for example, the user terminal T1-7 in the same base (FIG. 4 (11C)). At this time, the edge server SEm actually transmits a content push request message including the content B. And user terminal T1-7 preserve | saves the content B contained in the received content push request message (FIG. 4 (12C)).

  The acquisition and transmission of the related content by the edge server SE1 are performed, for example, when there is a margin in the bandwidth used for the line of the edge server SE1 or when the CPU usage rate is low. Further, the related content may be transmitted to a plurality of user terminals Tm-n in the same base. Further, for example, there is a user terminal Tm-n having a relatively low CPU usage rate, a user terminal Tm-n having a relatively large free space in the content cache area, or a user terminal Tm-n that is not reproducing content. It may be selected as a transmission destination of related content. Information on the CPU usage rate, the free space in the content cache area, and whether or not the content is being reproduced, for example, is periodically transmitted by the user terminal Tm-n, and the edge server SEm obtains the information. can do.

  When the user of the user terminal T1-1 wants to view the content B related to the content A after viewing the content A, as shown in FIG. Content B is to be acquired from the user terminal Tm-n. And since the content B is preserve | saved at the user terminal T1-7, the user terminal T1-1 can acquire a content from the user terminal T1-7. Therefore, the user terminal T1-1 does not need to transmit the message to the edge server SE1 and relay the content B. Therefore, the load on the edge server SE1 can be reduced.

[1.3.1 P2P control message relay]
A message used for exchanging information in the P2P network PW is referred to as a P2P control message. Examples of the P2P control message include a content location inquiry message, a search response message, a content request message, and a content request response message. As a proxy, the edge server SEm needs to relay a P2P control message between the user terminal Tm-n in the same base and the edge server SEm in another base and the user terminal Tm-n in another base. However, the edge server SEm needs to perform processing according to the content of the P2P control message that is not relayed as a proxy. Accordingly, an example of a method for the edge server SEm to perform appropriate processing according to the received P2P control message will be described below.

  For example, a port number different from the port number used for normal P2P control message exchange is assigned to each edge server SEm. This port number is a P2P control message relay port number used for exchanging P2P control messages relayed as a proxy by the edge server SEm. In the node information of the edge server SEm registered in the routing table, a port number used for normal P2P control message exchange is set. This is because each node transmits a P2P control message to other nodes using the port number of the node information registered in the routing table as the destination port number of the packet header. On the other hand, when each user terminal Tm-n relays the P2P control message to the edge server SEm in the same base, the port number different from the port number used for the exchange of the normal P2P control message is set as the destination of the packet header. The port number. In this case, the port number for P2P control message relay is set as the destination port number. The port number for relaying the P2P control message assigned to the edge server SEm in the same base may be registered in the user terminal Tm-n by a system administrator or a user when setting up the P2P software, for example. .

  The edge server SEm that has received the P2P control message can determine whether or not the received P2P control message is a message to be relayed by confirming which port number is received. When the edge server SEm receives a P2P control message with a port number used for exchange of a normal P2P control message, the edge server SEm performs normal processing according to the content of the message. On the other hand, when the edge server SEm receives the P2P control message with the port number for relaying the P2P control message, for example, the edge server SEm performs the following process.

  When the edge server SEm receives the content location inquiry message, the edge server SEm checks whether the content to be searched is stored in the content cache area. If the search target content is stored, the edge server SEm acquires the content from the content cache area, and transmits the content location inquiry message from the user node, that is, the user terminal Tm in the same base. -Send to n.

  On the other hand, when the search target content is not stored, the edge server SEm relays the received content location inquiry message according to the routing table. At this time, the edge server SEm assigns any unused port number to the received content request message. This port number is a port number different from the port number used for normal P2P control message exchange and the port number for relaying the P2P control message. The edge server SEm associates the assigned port number with the request source information including the IP address and port number of the user node and registers them in the relay management table. The IP address and port number of the user node are set as the source address and source port number in the packet header of the received message. Then, the edge server SEm relays the content location inquiry message using the assigned port number. In the content location inquiry message, the IP address and port number of the user node are set as request source information in addition to the source address and source port number of the packet header. This request source information is information for the root node that has received the content location inquiry message to directly send a search response message to the user node. The edge server SEm rewrites the IP address and port number of the user node in the request source information with the IP address and newly assigned port number of the edge server SEm. As a result, the root node transmits a search response message to the edge server SEm.

  The edge server SEm that has received the search response message can determine from the port number at the time of reception that the search response message is a message to be relayed. Therefore, the edge server SEm acquires request source information registered in the relay management table in association with the port number when the search response message is received. Then, the edge server SEm relays the search response message to the user terminal Tm-n in the same site as the user node based on the acquired request source information. The edge server SEm deletes the port number that became unnecessary and the request source information of the user node from the relay management table.

  Note that the edge server SEm may not relay the search response message. In this case, when relaying the content location inquiry message, the edge server SEm does not rewrite the request source information of the user node and does not have to assign a port number. As a result, the root node directly transmits a search response message to the user node.

  When the edge server SEm receives the content request message with the port number for relaying the P2P control message, the edge server SEm performs the same processing as when the content location inquiry message is received. Specifically, the edge server SEm assigns a port number and registers it in the relay management table. Then, the edge server SEm relays the content request message to the content holding node. In this case, the user terminal Tm-n as the user node includes the IP address and port number of the content holding node as content request destination information in the content request message transmitted to the edge server SEm. The edge server SEm can recognize which node is the relay destination content holding node by referring to the content request destination information included in the received content request message.

  The edge server SEm that has received the content request response message relays the received content request response message to the user node in the same manner as when the search response message is received.

[1.3.2 Content association]
When acquiring the related content, the edge server SEm determines which content is associated with which content using the related content definition file. The related content definition file is a file in which an association between contents is described. This related content definition file is created by a system administrator, for example. Then, the created related content definition file is distributed to each edge server SEm by the input server ST. The distribution of the related content definition file may be performed by, for example, DHT multicast disclosed in Japanese Patent Laid-Open No. 2007-053662. Each edge server SEm may acquire the related content definition file by accessing the input server ST periodically.

  FIG. 5 is a diagram showing an example of content association described in the association definition file. In the simplest example, as shown in FIG. 5A, the contents are associated one-to-one. In FIG. 5A, part 1 and part 2 of the movie are associated with each other. That is, contents of different versions such as the number of stories and the main part and the second part are associated with each other. In this case, the related content of the XX movie part 1 is the XX movie part 2 and the related content of the XX movie part 2 is the XX movie part 1. The arrows shown in FIG. 5 indicate that the contents are associated with each other.

  FIG. 5B is an example in which contents are associated in a one-to-many manner. In FIG. 5 (b), a XX movie CM (Commercial Message) is associated with each viewer group. That is, a plurality of contents including information related to the XX movie are associated with the content XX movie. Specifically, the related content of the movie is an M1 layer CM, an M2 layer CM, an F1 layer CM, and an F2 layer CM. On the other hand, the related contents of the M1 layer CM, the M2 layer CM, the F1 layer CM, and the F2 layer CM are XX movies. When the edge server SEm acquires any CM content, the edge server SEm acquires the movie content as the related content. At this time, the edge server SEm may acquire three CM contents other than the acquired contents as related contents from the four contents shown in FIG. That is, the edge server SEm may not only acquire the directly associated content from the content acquired first, but may acquire the related content by tracing all the associations.

  FIG. 5C is also an example in which the contents are associated with one another. In FIG. 5C, a plurality of subjects included in the literary mathematics are associated with the curriculum explanation of the literary mathematics. That is, content that collectively describes these subjects is associated with lecture content of a plurality of subjects included in humanities mathematics. Specifically, the related contents of curriculum explanation of humanities mathematics are mathematics I, mathematics II, mathematics A, and mathematics B. On the other hand, the related content of Mathematics I, Mathematics II, Mathematics A, and Mathematics B is a curriculum explanation of humanities mathematics.

  FIG. 5D is an example in which contents are associated in a plural-to-multiple manner. In FIG. 5 (d), a plurality of subjects included in each mathematics are associated with a description of required high school mathematics, a description of high school mathematics, and a description of high school mathematics. Specifically, the related contents of the compulsory explanation of high school mathematics are Mathematics I and Mathematics II. The related contents of the explanation of the high school mathematics are mathematics I, mathematics II, mathematics A, and mathematics B. The related contents of the explanation of the science of high school mathematics are mathematics I, mathematics II, mathematics III, mathematics A, mathematics B, and mathematics C. On the other hand, the related contents of Mathematics I and Mathematics II are a compulsory explanation of high school mathematics, an explanation of the arts system, and an explanation of the science system. The related contents of the mathematics A and B are explanations of high school mathematics and science. The related contents of Mathematics III and Mathematics C are explanations of the science of high school mathematics. When the edge server SEm traces all the associations from the first acquired content and acquires the related content, the first one of the nine content items shown in FIG. Eight contents other than the acquired contents are acquired as related contents. This is the same as the case of acquiring the related content by tracing all the associations described in FIG.

[1.4 Configuration and function of input server ST]
Next, the configuration and function of the input server ST will be described with reference to FIG.

  FIG. 6 is a diagram illustrating a schematic configuration example of the input server ST.

  As shown in FIG. 6, the input server ST includes a control unit 11 as a computer including a CPU having a calculation function, a working RAM, a ROM for storing various data and programs, and the like. In addition, the input server ST includes a storage unit 12 including an HD or the like for storing and storing various data and various programs. Further, the input server ST performs communication control of information with the management server SM and the like through the distribution center network NS, and communication unit 13 for performing communication control of information with the edge server SEm through the network NW and the like. It has. The control unit 11, the storage unit 12, and the communication unit 13 are connected to each other via a bus 14.

  The storage unit 12 stores node IDs, IP addresses, port numbers, and the like of each edge server SEm and each user terminal Tm-n. The storage unit 12 stores content to be distributed. The storage unit 12 stores a related content definition file. The storage unit 12 stores an operating system, a content distribution control program, an operation management program, a base server management program, and the like. These programs may be downloaded from a predetermined server on the distribution center network NS, for example. Further, these programs may be recorded on a recording medium and read via a drive of the recording medium, for example.

  The control unit 11 performs overall control of the entire input server ST when the CPU reads and executes a program stored in the storage unit 12 or the like.

[1.5 Edge server configuration and functions]
Next, the configuration and function of the edge server SEm will be described with reference to FIG.

  FIG. 7 is a diagram illustrating a schematic configuration example of the edge server SEm.

  As shown in FIG. 7, the edge server SEm includes a control unit 21 as a computer including a CPU having a calculation function, a working RAM, a ROM that stores various data and programs, and the like. In addition, the edge server SEm includes a storage unit 22 composed of an HD (hard disk) for storing and storing various data, various programs, and the like, and a buffer memory 23 for temporarily storing received content and the like. . The storage unit 22 is an example of a second storage unit. Furthermore, the edge server SEm includes a decoder unit 24 that decodes encoded video data (video information), audio data (audio information), and the like included in the content. Further, the edge server SEm performs a predetermined drawing process on the decoded video data and the like and outputs it as a video signal, and displays a video based on the video signal output from the video processor 25. And a display unit 26 such as a CRT or a liquid crystal display. Further, the edge server SEm converts the decoded audio data into an analog audio signal by D (Digital) / A (Analog) conversion, amplifies it by an amplifier, and outputs it, and this audio processing unit And a speaker 28 that outputs the audio signal output from the sound wave 27 as a sound wave. Furthermore, the edge server SEm controls communication of information with the user terminal Tm-n through the base network NLm, and controls communication of information with other edge servers SEm, input servers ST, etc. through the network NW. The communication part 29 for performing is provided. Furthermore, the edge server SEm includes an input unit (for example, a keyboard, a mouse, a remote controller, an operation panel, or the like) 30 that receives an instruction from a user and gives an instruction signal corresponding to the instruction to the control unit 21. Yes. The control unit 21, the storage unit 22, the buffer memory 23, the decoder unit 24, the communication unit 29, and the input unit 30 are connected to each other via a bus 31. As the edge server SEm, for example, in addition to a dedicated server device, a personal computer or the like can be applied. Note that when the user does not reproduce and use the content on the edge server, the decoder unit 24, the video processing unit 25, the display unit 26, the audio processing unit 27, the speaker 28, and the input unit 30 are unnecessary.

  The storage unit 22 stores a routing table using DHT, index information, content catalog information, a related content definition file, and the like. In addition, the storage unit 22 stores the IP address and port number of a contact node as an access destination when participating in the P2P network PW, the IP address and port number of the input server ST, and the like. Further, the storage unit 22 stores the base identification information of the base m where the edge server SEm is installed, and the node ID assigned to the edge server SEm. In addition, the storage unit 22 stores a use bandwidth upper limit value or a CPU use rate upper limit value that is a condition for acquisition and transmission of related content. A content cache area is allocated to a part of the storage capacity of the storage unit 22. Content is stored in this content cache area. The storage unit 22 stores an operating system, an edge server proxy program, P2P software, and the like. These programs may be downloaded from the input server ST, for example. Further, these programs may be recorded on a recording medium and read via a drive of the recording medium, for example. The edge server proxy program and the P2P software program are examples of the information communication processing program.

  The control unit 21 functions as a related content acquisition unit, a related content transmission unit, and a relay unit in the present invention when the CPU reads and executes a program stored in the storage unit 22 or the like.

[1.6 User terminal configuration and functions]
Next, the configuration and function of the user terminal Tm-n will be described with reference to FIG.

  FIG. 8 is a diagram illustrating a schematic configuration example of the user terminal Tm-n.

  As shown in FIG. 8, the user terminal Tm-n includes a control unit 41, a storage unit 42, a buffer memory 43, a decoder unit 44, a video processing unit 45, a display unit 46, an audio processing unit 47, a speaker unit 48, and a communication unit. 49, an input unit 50, and a bus 51. The basic configurations and functions of the control unit 41, the storage unit 42, the buffer memory 43, the decoder unit 44, the video processing unit 45, the display unit 46, the audio processing unit 47, the speaker unit 48, the input unit 50, and the bus 51 are as follows. The control unit 21, storage unit 22, buffer memory 23, decoder unit 24, video processing unit 25, display unit 26, audio processing unit 27, speaker unit 28, input unit 30, and bus 31 in the edge server SEm are the same. For example, a personal computer can be applied as the user terminal Tm-n.

  The communication unit 49 controls communication of information with other user terminals Tm-n and the edge server SEm through the base network NLm, and controls communication of information with the portal server SP and the like through the network NW.

  The storage unit 42 stores a routing table using DHT, index information, content catalog information, and the like. The storage unit 42 also has an IP address and a port number of a contact node that is an access destination when participating in the P2P network PW, an IP address and a port number of the input server ST, an IP address of the edge server SEm in the same site, and The port number and the like are stored. Further, the storage unit 42 stores the base identification information of the base m where the user terminal Tm-n is installed, and the node ID assigned to the user terminal Tm-n. In addition, a content cache area is allocated to a part of the storage capacity of the storage unit 42. Content is stored in this content cache area. The storage unit 42 stores an operating system, a user content acquisition program, P2P software, a Web browser program, a player program, and the like. Note that these programs may be downloaded from, for example, the edge server SEm or the portal server SP. Further, these programs may be recorded on a recording medium and read via a drive of the recording medium, for example.

  The control unit 41 functions as a content acquisition unit, a related content reception unit, a request information transmission unit, and a content reception unit in the present invention when the CPU reads and executes a program stored in the storage unit 42 or the like.

[1.7 Operation of content distribution system]
Next, the operation of the content distribution system S according to the present embodiment will be described with reference to FIGS. 9 to 12.

  In the content distribution system S, reproducible content such as moving image data is divided into a plurality of data. This divided individual data is called “content chunk”. A content ID is assigned to this content chunk in the same manner as normal content. Therefore, the content chunk can be acquired in the same manner as the normal content. When reproducing the content, the user terminal Tm-n performs reproduction while sequentially obtaining the content to be reproduced in units of content chunks. For example, when the user terminal Tm-n accesses the portal server SP and the user selects the content to be played back, the content IDs of a plurality of content chunks to be played back and the list information of the playback order are displayed. May be acquired from the portal server SP.

  9 to 12 mainly show processing related to acquisition of content chunks. The detailed processing related to the acquisition of normal content other than the content chunk is appropriately omitted.

  9 and 10 are flowcharts showing an example of processing in the control unit 41 of the user terminal Tm-n according to the present embodiment.

  The process of FIG. 9 is started when the user terminal Tm-n is turned on, for example. First, the control unit 41 executes various initialization processes of a program for acquiring and reproducing content from the P2P network PW (step S1).

  Next, the control unit 41 determines whether or not there is a normal reproduction request from the user (step S2). In addition, after the normal reproduction request is once made, if the content requested to be reproduced is being reproduced, it is determined that there is no normal reproduction request. At this time, if there is a normal playback request from the user (step S2: YES), the control unit 41 resets the index of the content chunk of the content to be played back to the top in the playback order (step S3). This index indicates the order of the content chunks to be reproduced at present.

  Next, the control unit 41 determines whether or not the content chunk indicated by the current index is stored in the content cache area (step S4). At this time, when the content chunk indicated by the current index is stored in the content cache area (step S4: NO), the control unit 41 reads out the content chunk indicated by the current index from the content cache area. The content chunk is played back (step S7).

  On the other hand, if the content chunk indicated by the current index is not stored in the content cache area (step S4: YES), the control unit 41 sends a search request message in the same site by L2 broadcast in order to acquire this content. (Step S5).

  Next, the control unit 41 determines whether or not the content chunk search has failed (step S6). For example, when a content chunk is transmitted from another user terminal Tm-n before a predetermined time has elapsed since the L2 broadcast transmission of the search request message, the content chunk search is determined to be successful. If a certain time has elapsed without the content chunk being transmitted, the content chunk search is determined to have failed. At this time, if the search for the content chunk fails (step S6: YES), the control unit 41 acquires the content from the edge server SEm at the other base or the user terminal Tm-n at the other base as the content acquisition means. . Specifically, the control unit 41 transmits a content location inquiry message to the edge server SEm in the same base as a request information transmission unit (step S10).

  On the other hand, when the search for the content chunk is successful (step S6: NO), the control unit 41 reproduces the content chunk received from the other user terminal Tm-n (step S7). The received content chunk is stored in the content cache area.

  When the content chunk is played back, the control unit 41 determines whether or not the playback of the content chunk in the playback order has reached the last content chunk based on the current index value (step S8). . At this time, if the playback order has not been played back until the last content chunk (step S8: YES), the control unit 41 adds 1 to the current index (step S9), and proceeds to step S4. .

  When the process of step S10 is completed, or when the playback has been performed up to the content chunk whose playback order is the last in step S8 (step S8: NO), the control unit 41 determines whether or not there has been a power-off request from the user. Is determined (step S11). At this time, if there is no power-off request (step S11: NO), the control unit 41 proceeds to step S2.

  In step S2, when there is no normal reproduction request from the user (step S2: NO), the control unit 41 determines whether any message is received from the edge server SEm in the same base (step S13). . At this time, if the control unit 41 receives a message from the edge server SEm in the same site (step S13: YES), the control unit 41 determines whether the received message is a content chunk search response message (step S13). S14). At this time, if the received message is a content chunk search response message, the control unit 41 transmits a content request message to the edge server SEm in the same site (step S15). This content request message includes the IP address and port number of the content holding node acquired from the index information included in the received search response message as the content request destination information. After completing this process, the control unit 41 proceeds to step S11.

  On the other hand, when the received message is not a content chunk search response message (step S14: NO), the control unit 41 determines whether the received message is a content request response message (step S16). That is, the control unit 41 determines whether a content chunk has been received as a content receiving unit. At this time, when the received message is a content request response message (step S16: YES), the control unit 41. The content chunk included in the content request response message is stored in the content cache area (step S17). Next, the control unit 41 transmits a publish message for the stored content chunk to the root node (step S18). And the control part 41 reproduces | regenerates the preserve | saved content chunk (step S7).

  On the other hand, when the received message is not a content request response message (step S16: NO), the control unit 41 determines whether or not the received message is a content push request message (step S19). That is, the control unit 41 determines whether the related content is received as the related content receiving unit. At this time, when the received message is a content push request message (step S19: YES), the control unit 41 stores the related content included in the content push request message in the content cache area (step S20). Next, the control unit 41 transmits a publish message to the root node for the stored related content (step S21), and proceeds to step S11.

  In step S13, when the control unit 41 has not received a message from the edge server SEm in the same base (step S13: NO), as shown in FIG. 10, the other user terminal Tm- From n, it is determined whether a search request message by L2 broadcast has been received (step S22). At this time, if the control unit 41 receives a search request message from another user terminal Tm-n in the same base (step S22: YES), is the requested content chunk stored in the content cache area? It is determined whether or not (step S23). At this time, if the requested content chunk is stored in the content cache area (step S23: YES), the control unit 41 transmits the requested content chunk to the requesting user terminal Tm-n ( Step S24). When the content chunk requested in step S23 is not stored in the content cache area (step S23: NO), or when the process of step S24 is completed, the control unit 41 proceeds to step S11.

  In step S22, the control unit 41 determines whether or not a P2P control message has been received from another device when the search request message has not been received from another user terminal Tm-n in the same base ( Step S35). As other devices, all user terminals Tm-n and all edge servers SEm are targeted regardless of whether or not they are in the same location as the user terminal Tm-n itself. At this time, if the control unit 41 has not received a P2P control message from another device (step S35: NO), the control unit 41 proceeds to step S11.

  On the other hand, when receiving the P2P control message from another device (step S35: YES), the control unit 41 determines whether or not the received P2P control message is a content location inquiry message (step S25). At this time, if the received P2P control message is a content location inquiry message (step S25: YES), the control unit 41 determines that the user terminal Tm-n itself is the root node of the content chunk for which the location inquiry is requested. It is determined whether or not (step S26). At this time, when the user terminal Tm-n itself is the root node (step S26: YES), the control unit 41 requests a search response message including the index information of the content holding node in the content location inquiry message. It transmits to the node which original information shows (step S27).

  On the other hand, when the user terminal Tm-n itself is not the root node (step S26: NO), the control unit 41 relays the content location inquiry message to another node using the routing table (step S28). The control part 41 will transfer to step S11, after finishing the process of step S27 or S28.

  In step S25, when the received P2P control message is not a content location inquiry message (step S25: NO), the control unit 41 determines whether the received P2P control message is a content request message (step S25). S29). At this time, if the received P2P control message is a content location inquiry message (step S29: YES), the control unit 41 sends the content chunk indicated by the content ID included in the content location inquiry message from the content cache area. The content request response message including the read content chunk is read and transmitted to the node that is the source of the content request message (step 30).

  In step S29, when the received P2P control message is not a content location inquiry message (step S29: NO), the control unit 41 determines whether the received P2P control message is a publish message (step S31). ). At this time, when the received P2P control message is not a publish message (step S31: NO), the control unit 41 proceeds to step S11. On the other hand, when the received P2P control message is a publish message (step S31: YES), the control unit 41 determines whether the user terminal Tm-n itself is a root node (step S32). At this time, when the user terminal Tm-n itself is the root node (step S32: YES), the control unit 41 registers the index information of the content holding node in the index information cache (step S33). On the other hand, when the user terminal Tm-n itself is not the root node (step S32: NO), the control unit 41 relays the publish message to another node using the routing table (step S34). After finishing the process of step S33 or S34, the control unit 41 proceeds to step S11.

  In step S11, when there is a power-off request from the user (step S11: YES), the control unit 41 executes various termination processes for terminating the program (step S12). And the control part 41 complete | finishes the process shown in FIG.9 and FIG.10.

  11 and 12 are flowcharts showing an example of processing in the control unit 21 of the edge server SEm according to the present embodiment.

  The process of FIG. 11 is started when the power of the edge server SEm is turned on, for example. First, the control unit 21 executes various initialization processes of a program for functioning as the edge server SEm (step S51).

  Next, the control unit 21 determines whether or not a content chunk has been received as a content request response message from the edge server SEm at another site (step S52). At this time, when the content chunk is received from the edge server SEm at another base (step S52: YES), the control unit 21 stores the received content chunk in the content cache area (step S53). Next, the control unit 21 transmits the content chunk as a relay unit to the user terminal Tm-n that has requested the received content chunk (step S54). Specifically, the control unit 21 acquires request source information corresponding to the port number that received the content chunk from the relay management table stored in the storage unit 22. Then, the control unit 21 sets the IP address and port number of the acquired request source information to the transmission destination IP address and transmission destination port number of the header of the content chunk packet, and transmits the content chunk.

  Next, the control unit 21 determines whether or not the acquired content is registered in the related content definition file stored in the storage unit 22 (step S55). At this time, when the acquired content is registered in the related content definition file (step S55: YES), the control unit 21 refers to the related content definition file and stores the content cache among the related content of the acquired content. It is determined whether there is related content not stored in the area (step S56).

  At this time, if there is related content that is not stored in the content cache area among the related content of the acquired content (step S56: YES), the control unit 21 uses the related content that is not stored as the related content acquisition unit. Content is acquired (step S57). Specifically, the control unit 21 transmits a content request message to the root node, and receives a search response message transmitted from the root node. Next, the control unit 21 transmits a content request message to any content holding node of the related content, and receives the related content transmitted from the content holding node.

  Next, the control unit 21 stores the acquired related content in the content cache area (step S58). Next, the control unit 21 transmits a publish message about the stored related content to the root node (step S59). Next, the control unit 21 transmits the stored related content to any user terminal Tm-n in the same site as the related content transmission unit (step S60). Specifically, the control unit 21 transmits a content push request message including related content to the user terminal Tm-n. When this process is finished, the control unit 21 proceeds to step S56.

  Note that the processing in steps S57 to S60 is performed when the edge server SEm itself performs information communication when the used bandwidth is equal to or lower than the used bandwidth upper limit value or the CPU usage rate of the control unit 21 is equal to or lower than the CPU used rate upper limit value. It may be executed when In this case, the processes in steps S57 to S60 are executed by a thread different from the other processes shown in FIGS.

  When the content acquired in step S55 is not registered in the related content definition file (step S55: NO), the control unit 21 stores all the related content of the content acquired in step S56 in the content cache area. If yes (step S56: NO), it is determined whether or not there is a power-off request from the user (step S61). At this time, when there is no power-off request (step S61: NO), the control unit 21 proceeds to step S52.

  In step S52, when the content chunk has not been received from the edge server SEm at the other base (step S52: NO), the control unit 21 determines whether a P2P control message has been received from another device (step S52: NO). Step S63). At this time, when the P2P control message is not received from another device (step S63: NO), the control unit 21 sends a search request message by L2 broadcast from another user terminal Tm-n in the same base. It is determined whether or not it has been received (step S70). At this time, the control unit 21 may or may not receive a search request message by L2 broadcast from another user terminal Tm-n in the same site (step S70: YES or NO), the process proceeds to step S61 without performing any special processing. That is, the control unit 21 ignores the search request message by L2 broadcast. That is, the control part 21 does not need to perform determination of step S70. In step S63, if the control unit 21 receives a P2P control message from another device (step S63: YES), the control unit 21 determines whether the received P2P control message is a content location inquiry message (step S64). ). At this time, if the received P2P control message is a content location inquiry message (step S64: YES), the control unit 21 determines whether the content chunk for which the location inquiry is requested is stored in the content cache area. Is determined (step S65). At this time, when the content chunk requested to be located is stored in the content cache area (step S65: YES), the control unit 21 reads the content chunk from the content cache area and reads the read content chunk. Is transmitted to the node indicated by the request source information included in the content location inquiry message (step S66).

  On the other hand, when the content chunk for which the location inquiry is requested is not stored in the content cache area (step S65: NO), the edge server SEm itself makes the content chunk for which the location inquiry is requested. It is determined whether or not it is a root node (step S67). At this time, when the edge server SEm itself is the root node (step S67: YES), the control unit 21 sends the search response message including the index information of the content holding node to the request source information included in the content location inquiry message. Is transmitted to the node indicated by (step S68).

  On the other hand, when the edge server SEm itself is not the root node (step S67: NO), the control unit 21 relays the content location inquiry message to another node using the routing table (step S69). At this time, when the content location inquiry message is received at the port number for relaying the P2P control message, the control unit 21 performs processing as a relay unit. Specifically, the control unit 21 assigns an unused port number to the content location inquiry message, and registers this port number and request source information including the IP address and port number of the user node in the relay management table. To do. Further, the control unit 21 rewrites the IP address and port number of the user node in the request source information of the content location inquiry message with the IP address and newly assigned port number of the edge server SEm itself. Then, the edge server SEm transmits a content location inquiry message to another node. When the control section 21 finishes the process of step S68 or S69, the control section 21 proceeds to step S61.

  In step S64, if the received P2P control message is not a content location inquiry message (step S64: NO), the control unit 21 determines whether the received P2P control message is a search response message as shown in FIG. It is determined whether or not (step S71). At this time, if the received P2P control message is a search response message (step S71: YES), the control unit 21 determines whether the received search response message is a message addressed to the user terminal Tm-n in the same site. It is determined whether or not (step S72). For example, if the port number that received the search response message is registered in the relay management table stored in the storage unit 22, this search response message is addressed to the user terminal Tm-n in the same base. On the other hand, if the port number that received the search response message is not registered in the relay management table, the search response message is addressed to the edge server SEm itself. At this time, when the received search response message is a message addressed to the user terminal Tm-n in the same site (step S72: YES), the control unit 21 uses this search response message as a relay means in the same site. To the user terminal Tm-n (step S73). Specifically, the control unit 21 acquires request source information corresponding to the port number that received the search response message from the relay management table. Then, the control unit 21 sets the IP address and port number of the acquired request source information to the transmission destination IP address and transmission destination port number of the packet header of the search response message, and transmits the search response message.

  On the other hand, when the received search response message is a message addressed to the edge server SEm within the same base (step S72: NO), the control unit 21 transmits a content request message to any content holding node. (Step S74). When the control section 21 finishes the process of step S73 or S74, the control section 21 proceeds to step S61.

  In step S71, if the received P2P control message is not a search response message (step S71: NO), the control unit 21 determines whether the received P2P control message is a content request message (step S75). ). At this time, when the received P2P control message is a content request message (step S75: YES), the control unit 21 determines whether the received content request message is a message addressed to a device at another base. (Step S76). For example, when the port number that received the content request message is not the port number for relaying the P2P control message, the content request message is addressed to the edge server SEm itself. On the other hand, if the port number that received the content request message is the port number for relaying the P2P control message, the content request message is addressed to a device at another site. At this time, if the received content request message is a message addressed to a device at another base (step S76: YES), the control unit 21 sends the content request message to a device at another base as a destination as a relay unit. Relay (step S77).

  On the other hand, when the received content request message is addressed to the edge server SEm itself in the same base (step S76: NO), the control unit 21 reads the requested content from the content cache area and reads it. The received content chunk is transmitted to the node that has transmitted the content request message (step S78). When the control section 21 finishes the process of step S77 or S78, the control section 21 proceeds to step S61.

  In step S75, if the received P2P control message is not a content request message (step S75: NO), the control unit 21 determines whether the received P2P control message is a publish message (step S79). . At this time, when the received P2P control message is not a publish message (step S79: NO), the control unit 21 proceeds to step S61. On the other hand, when the received P2P control message is a publish message (step S79: YES), the control unit 21 determines whether the edge server SEm itself is the root node of the content indicated by the content ID included in the publish message. Is determined (step S80). At this time, when the edge server SEm itself is the root node (step S80: YES), the control unit 21 registers the index information of the content holding node in the index information cache (step S81). On the other hand, when the edge server SEm itself is not the root node (step S80: NO), the control unit 21 relays the publish message to another node using the routing table (step S82). The control part 21 will transfer to step S61, after finishing the process of step S81 or S82.

  As described above, according to the present embodiment, when the user terminal Tm-n acquires content from the edge server SEm at another base, the user terminal Tm-n at another base, or the input server ST, the edge server SEm The related content related to the acquired content is acquired from the edge server SEm at another base, the user terminal Tm-n at another base, or the input server ST. Further, the edge server SEm transmits the acquired related content to any user terminal Tm-n in the same base. Then, the user terminal Tm-n that has received the related content stores the received related content in the content cache area.

  Accordingly, content related to content acquired by a certain user terminal Tm-n is stored by any user terminal Tm-n in the same base as the acquired user terminal Tm-n. The content related to the content acquired by the user terminal Tm-n is considered to be relatively likely to be requested to the edge server SEm in the future among the content that has not been acquired yet. Therefore, when the user terminal Tm-n that has acquired the content acquires content related to the content, it can be acquired from the user terminal Tm-n in the same base. This avoids concentration of content requests on the edge server SEm. Therefore, the load on the edge server SEm can be reduced, and content acquisition by the user terminal Tm-n can be performed smoothly.

  Even if the content required by the user terminal Tm-n is not stored in the other user terminal Tm-n and the edge server SEm in the same site, the content related to the content is stored in the same site. Can be stored in any user terminal Tm-n connected to the.

  In addition, when the user terminal Tm-n first tries to acquire content from another user terminal Tm-n in the same base and cannot acquire from other user terminals Tm-n in the same base, The content is acquired from the edge server SEm, the user terminal Tm-n at the other base, or the input server ST.

  Therefore, when the content required by the user terminal Tm-n is stored in another user terminal Tm-n in the same base, the content is requested from the other user terminal Tm-n in preference to the edge server SEm. Content is acquired. Therefore, the load on the edge server SEm can be reduced. Further, the content transmission load is distributed to a plurality of user terminals Tm-n in the same site. Therefore, content acquisition by the user terminal Tm-n can be performed smoothly.

  In addition, when the user terminal Tm-n has not acquired content from other user terminals Tm-n in the same base, the content is acquired from the edge server SEm in the same base, and the edge server SEm in the same base is acquired. When the content is not stored, the content is acquired from the edge server SEm at another base, the user terminal Tm-n at another base, or the input server ST via the edge server SEm in the same base.

  Therefore, when the content required by the user terminal Tm-n is stored in the edge server SEm in the same base, the edge server SEm in another base, the user terminal Tm-n in the other base, and the input server ST. Also, the content is acquired from the edge server SEm in the same site with priority. Therefore, traffic on the line connected from the base network NLm to the network NW is reduced, and content can be acquired efficiently.

  Further, the user terminal Tm-n transmits a content location inquiry request message to the edge server SEm at the other base, the user terminal Tm-n at the other base, or the input server ST via the edge server SEm in the same base. When the edge server SEm that has received the content location inquiry request message from the user terminal Tm-n in the same base stores the content in the content cache area of the edge server SEm itself, the content location inquiry request message is relayed. Instead, the content stored in the content cache area is transmitted to the user terminal Tm-n.

  Therefore, when the edge server SEm stores the content requested from the user terminal Tm-n in the same base, the edge server SEm includes the edge server SEm at the other base, the user terminal Tm-n at the other base, and the input. There is no need to acquire content from the server ST. Therefore, content acquisition by the user terminal Tm-n can be performed in a short time.

  When the edge server SEm that has received the content location inquiry request message from the user terminal Tm-n in the same base does not store the content in the content cache area of the edge server SEm itself, the content location inquiry request message is displayed. Relay to the edge server SEm at another base, the user terminal Tm-n at another base, or the input server ST. Further, the edge server SEm receives the content transmitted from the edge server SEm at another base, the user terminal Tm-n at another base, or the input server ST and relays it to the user terminal Tm-n in the same base. Further, the edge server SEm acquires related content related to the relayed content. Then, the edge server SEm stores the acquired related content in the content cache area. Further, the edge server SEm transmits the acquired related content to any user terminal Tm-n in the same base.

  Accordingly, content that is considered to be relatively likely to be requested from the user terminal Tm-n is stored in the edge server SEm, so that the usage efficiency of the content cache area of the edge server SEm can be improved. Further, since the user terminal Tm-n acquires content via the edge server SEm, the edge server SEm can reliably recognize the content acquired by the user terminal Tm-n. Therefore, the related content can be surely stored in the user terminal Tm-n in the same base.

  Further, when the edge server SEm uses the bandwidth used when the edge server SEm itself performs information communication, or when the CPU usage rate of the control unit 21 is less than or equal to the CPU usage rate upper limit value. In addition, the related content is acquired and transmitted.

  Therefore, it is possible to prevent an increase in the load on the edge server SEm when acquiring related content. Therefore, content acquisition by the user terminal Tm-n can be performed smoothly.

[2. Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.

  The general configuration of the content distribution system S, the basic mechanism of the P2P network PW, and the communication protocol in the present embodiment are the same as those in the first embodiment. The configurations of the input server ST, the edge server SEm, and the user terminal Tm-n are the same as those in the first embodiment.

  In this embodiment, when the user terminal Tm-n acquires content, priority is given to the acquisition destination of content. When searching for the location of content, the user terminal Tm-n transmits a content location inquiry message and receives a search response message without going through the edge server SEm in the same site. The transmission / reception method in this case is as described in the outline of the peer-to-peer network described above. The search request message is not broadcast as in the first embodiment.

  The user terminal Tm-n determines a content holding node as a content acquisition destination based on the index information and the priority order included in the received search response message. Then, when the determined content holding node is the user terminal Tm-n in the same base or the edge server SEm in the same base, the user terminal Tm-n transmits a content request message directly to the content holding node. To do. On the other hand, when the determined content holding node is the edge server SEm at another base, the user terminal Tm-n at another base, or the input server ST, the user terminal Tm-n passes through the edge server SEm in the same base. Get content. The P2P control message relayed by the edge server SEm is only the content request message and the content request response message transmitted at this time. The control method of the P2P control message is the same as that in the first embodiment. Then, the edge server SEm acquires the related content of the content included in the relayed content request response message and transmits it to any user terminal Tm-n in the same base. And user terminal Tm-n which received the related content preserve | saves this related content.

  The priorities for acquiring content are shown below.

First place: User terminal Tm-n in the same base
2nd: Edge server SEm in the same base
3rd place: Edge server SEm at other sites
4th: User terminal Tm-n at another base
5th place: Input server ST

  The priority order of the user terminal Tm-n and the edge server SEm in the same base is set higher than the priority order of the user terminal Tm-n and the edge server SEm in another base. The reason is to reduce the traffic of the communication line Lm.

  The priority order of the user terminals Tm-n in the same base is set higher than the priority order of the edge server SEm in the same base. Content that is likely to be downloaded by the user terminal Tm-n is stored in the content cache area of the edge server SEm. Further, the storage capacity of the content cache area of the edge server SEm is larger than the storage capacity of the content cache area of the user terminal Tm-n. For this reason, the edge server SEm is more likely to require content than the user terminal Tm-n. Therefore, in order to reduce the load on the edge server SEm, the priority is set as described above.

  The priority order of the edge server SEm at the other base is set higher than the priority order of the user terminal Tm-n at the other base. Depending on the base m, the base network NLm may be constructed by connecting a plurality of networks via network devices such as router devices. In this case, if a user terminal Tm-n as a content holding node is connected to a network far from the network NW, the content transmitted from the user terminal Tm-n passes through many network devices. . This places a load on these network devices and reduces content acquisition efficiency. Therefore, in order to reduce the load on the network device, the above-described priorities are set. Here, it is assumed that the base network NLm is composed of relay devices such as a plurality of routers. In this case, the edge server SEm or user terminal Tm-n belonging to the base network NLm includes a device that connects to the network NW via a relay device and a device that connects to the network NW without using a relay device. There is. In this case, the load on the relay device can be reduced by connecting the edge server SEm to the network NW without going through the network device. Alternatively, the edge server SEm may be connected to a network relatively close to the network from the network NW among a plurality of devices connected to the base network NLm. To be close to the network means that the number of relay devices to be relayed is small when connecting to the network NW. The network distance from the network NW to a network to which a certain device is connected is the number of networks through which data passes from the network NW to the network to which the device is connected, or the network through which the data passes. The number of devices. The smaller the number of network devices through which data passes, the closer the distance from the network NW.

  The priority of the input server ST is the lowest. The reason is that since the input server ST is a transmission source of all contents, it is necessary to reduce the load on the input server ST as much as possible.

  In order to acquire the content based on the priority order set in this way, when the node storing the content transmits the publish message, the base identification information of the base m where the node itself is installed is transmitted in the publish message. And the node type. The base identification information is identification information of the base m. The node type indicates whether the content holding node is the user terminal Tm-n or the edge server SEm. The root node that has received the publish message stores index information that includes the node information of the content holding node included in the publish message, the content ID of the stored content, the site identification information of the content holding node, the node type, and the like. When the root node receives the content location inquiry message, the root node transmits index information including the base identification information and the node type to the user node. Then, the user node determines a content holding node as a content acquisition destination based on the base identification information and the node type included in the received index information and the priority.

  FIG. 13 is a diagram illustrating an example of contents registered in the index information. Note that the index information shown in FIG. 13 is obtained by integrating the index information of a plurality of contents. Further, in the node information column of FIG. 13, the code of the edge server SEm as the content holding node or the code of the user terminal Tm-n is shown instead of the node information. In the content ID column of FIG. 13, a content name is shown instead of the content ID. In the base identification information column, an office name as an example of the base identification information is shown.

  As illustrated in FIG. 13, for example, the content whose content name is “movie 1” is stored in the edge server SE1, the user terminal T1-1, the user terminal T1-2, and the edge server SE3. In this case, the user terminal T1-3 as the user node acquires the content of “movie 1” from the user terminal T1-1 or the user terminal T1-2 having the first priority. When the user node is the user terminal T3-1, the content of “movie 1” is acquired from the edge server SE3 having the second highest priority. When the user node is the user terminal T2-1, the content of “movie 1” is acquired from the edge server SE1 or edge server SE3 having the third highest priority. For example, the content whose content name is “Drama 2” is stored in the user terminal T2-2. In this case, the user terminal T1-1 as a user node acquires the content of “drama 2” from the user terminal T2-2 having the fourth highest priority. The content whose content name is “Movie 3” is not stored in any node. In this case, the user node acquires the content of “movie 3” from the input server ST having the fifth priority.

  Next, the operation of the content distribution system S will be described with reference to FIG.

  FIG. 14 is a flowchart illustrating a processing example of content acquisition processing in the control unit 41 of the user terminal Tm-n according to the present embodiment.

  The process of FIG. 14 is started when the user terminal Tm-n receives a search response message from the root node after transmitting a content location inquiry message as a user node. First, the control unit 41 acquires the base identification information of the base m where the user terminal Tm-n itself is installed and the node type of the user terminal Tm-n itself from the setting information stored in the storage unit 42. (Step S101).

  Next, the control unit 41 determines whether or not the combination of the site identification information and the node type that matches the combination of the site identification information and the node type acquired from the setting file is set in the index information included in the content inquiry response message. Is determined (step S102). That is, the control unit 41 determines whether any user terminal Tm-n in the same base stores the content. At this time, if the combination of the site identification information and the node type that matches the combination of the site identification information and the node type acquired from the setting file is set (step S102: YES), the control unit 41 proceeds to step S103. Transition. In step S103, the control unit 41 acquires content from an arbitrary user terminal Tm-n among the user terminals Tm-n in the same site where the node information is included in the index information.

  On the other hand, if the combination of the site identification information and the node type that matches the combination of the site identification information and the node type acquired from the setting file is not set (step S102: NO), the control unit 41 proceeds to step S104. To do. In step S104, the control unit 41 includes, in the index information included in the content inquiry response message, a combination of the base identification information that matches the base identification information acquired from the setting file and the node type indicating the edge server. Determine whether it is set. That is, the control unit 41 determines whether or not the edge server SEm in the same base stores the content. At this time, the control unit 41 sets a combination of the base identification information that matches the base identification information acquired from the setting file and the node type indicating the edge server (step S104: YES). The process proceeds to step S105. In step S105, the control unit 41 acquires content from the edge server SEm in the same site where the node information is included in the index information.

  On the other hand, when the site identification information that matches the site identification information acquired from the setting file is not set (step S104: NO), the control unit 41 uses the edge server SEm in the same site as the content acquisition unit. The content is acquired from the content holding node.

  Specifically, the control unit 41 determines whether or not a node type indicating an edge server is set in the index information included in the content inquiry response message (step S106). That is, the control unit 41 determines whether or not the edge server SEm at another base stores the content. At this time, if the node type indicating the edge server is set (step S106: YES), the control unit 41 is the same from the edge server SEm of the other base where the node information exists in the index information. Content is acquired via the edge server SEm in the site (step S107). Specifically, the control unit 41 transmits a content request message addressed to the edge server SEm at another base to the edge server SEm within the same base. The control unit 21 of the edge server SEm edge server SEm in the same site that has received the content request message acquires content from the edge server SEm at another site that is a content holding node. And the control part 21 preserve | saves the acquired content in a content cache area. Further, the control unit 21 relays the acquired content to the user terminal Tm-n that is the transmission source of the content request message. The control unit 41 of the user terminal Tm-n receives content relayed from the edge server SEm in the same base.

  On the other hand, when the node type indicating the edge server is not set (step S106: NO), the control unit 41 determines whether the node type indicating the user terminal is set. (Step S108). That is, the control unit 41 determines whether or not the user terminal Tm-n at another base stores the content. At this time, when the node type indicating the user terminal is set (step S108: YES), the control unit 41 starts from the user terminal Tm-n at the other base where the node information exists in the index information. The content is acquired via the edge server SEm in the same base (step S107).

  On the other hand, when the node type indicating the user terminal is not set (step S108: NO), the control unit 41 acquires content from the input server ST via the edge server SEm in the same base. (Step S109).

  When the processing of step S103, S105, S107, or S109 is completed, the control unit 41 stores the acquired content in the content cache area (step S110). Next, the control unit 41 transmits a publish message toward the root node (step S111). This publish message includes the node information of the user terminal Tm-n, the content ID of the stored content, the base identification information acquired from the setting file, and the node type. When this process is completed, the control unit 41 ends the content acquisition process.

  When the edge server SEm acquires content in step S107 or S109, the edge server SEm acquires related content of the acquired content.

  Note that the content acquisition process shown in FIG. 14 can also be applied to the acquisition of a content chunk at the time of content playback shown in FIGS.

  As described above, also according to the present embodiment, any user terminal Tm that connects content acquired by a certain user terminal Tm-n in the same site as the acquired user terminal Tm-n. Saved by -n. Therefore, when the user terminal Tm-n that has acquired the content acquires content related to the content, it can be acquired from the user terminal Tm-n in the same base. This avoids concentration of content requests on the edge server SEm. Therefore, the load on the edge server SEm can be reduced, and content acquisition by the user terminal Tm-n can be performed smoothly.

[3. Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG.

  The general configuration of the content distribution system S in the present embodiment is the same as that in the first embodiment. However, in this embodiment, two types of peer-to-peer networks for content distribution are constructed. The configurations of the input server ST, the edge server SEm, and the user terminal Tm-n are the same as those in the first embodiment.

  FIG. 15 is a diagram illustrating a construction example of the P2P network PW2 and the base P2P network PLm in the content distribution system S according to the present embodiment.

  As shown in FIG. 15, the first peer-to-peer network is a P2P network PW2 constructed on a network NW. The second peer-to-peer network is a base P2P network PLm constructed for each base m.

  The P2P network PW2 is a logical overlay network constructed on the network NW. The P2P network PW2 is a network formed by connecting any of a plurality of edge servers SEm among the edge servers SEm constituting the content distribution system S. The input server ST may be connected to the P2P network PW2.

  The base P2P network PLm is a logical overlay network constructed on the base network NLm. This peer-to-peer network PLm is a network formed by connecting a plurality of user terminals Tm-n and edge servers SEm among user terminals Tm-n connected to the base NLm.

  In both peer-to-peer networks, the basic mechanism and communication protocol are the same as those of the P2P network PW in the first embodiment, and thus detailed description thereof is omitted. However, when the user terminal Tm-n acquires content catalog information, for example, the user terminal Tm-n acquires content catalog information from the edge server SEm by periodically accessing the edge server SEm in the same base. .

  FIG. 16 is a conceptual diagram illustrating an example of a state where the user terminal Tm-n acquires content in the content distribution system S according to the present embodiment.

  A user of a certain user terminal Tm-n, for example, the user terminal T2-6 requests the reproduction of the content A, for example. Then, the user terminal T2-6 first tries to acquire the content A from the base P2P network PL2 in which the user terminal T2-6 itself participates. First, the user terminal T2-6 transmits a content location inquiry toward the root node of the content A participating in the base P2P network PL2 (FIG. 16 (1)). This content location inquiry is transferred from, for example, the user terminal T2-5 to the user terminal T2-1 that is the root node.

  The user terminal T2-1 transmits a search response message including the index information of the content A to the user terminal T2-6 (FIG. 16 (2)). When any of the nodes participating in the base P2P network PL2 stores the content A, the index information includes the node information of the content holding node. Accordingly, the user terminal T2-6 transmits a content request message to any content holding node, for example, the user terminal T2-4 (FIG. 16 (3A)). The user terminal T2-4 transmits the content A stored in the content cache area of the user terminal T2-4 itself to the user terminal T2-6 (FIG. 16 (4A)). Then, the user terminal T2-6 starts playing the received content.

  On the other hand, for example, when the user terminal T1-2 cannot acquire the content B requested for reproduction from the base P2P network PL1, the user terminal T1-2 acquires the content via the edge server SE1. Specifically, the user terminal T1-2 transmits a content proxy acquisition request message to the edge server SE1 (FIG. 16 (3B)).

  The edge server SE1 that has received the content proxy acquisition request message acquires the content A from the content cache area and transmits it to the user terminal T1-2 when the content A is stored in the content cache area. On the other hand, the edge server SEm acquires the content B from the P2P network PW2 when the content A is not stored in the content cache area. First, the edge server SE1 transmits a content location inquiry message toward the root node of the content B (FIG. 16 (4B)). This content location inquiry message is transferred to the root node, for example, the edge server SE5. The edge server SE5 transmits a search response message including the index information of the content B to the edge server SE1 (FIG. 16 (5B)). The edge server SE1 transmits a content request message to the edge server SE4 that is one of the content holding nodes of the content B ((6B) in FIG. 16). The edge server SE4 transmits the content B stored in the content cache area of the edge server SE4 itself to the edge server SE1 (FIG. 16 (7B)). The edge server SE1 stores the received content B and transmits it to the user terminal T1-2 (FIG. 16 (8B)).

  Further, the edge server SE1 acquires the related content of the content B, for example, the content C (FIG. 16 (9B)). The edge server SE1 stores the acquired content C and transmits the content C to any user terminal Tm-n, for example, the user terminal T1-7 in the same base (FIG. 16 (10B)). And user terminal T1-7 preserve | saves the received content B (FIG. 16 (11B)).

  As described above, also according to the present embodiment, any user terminal Tm that connects content acquired by a certain user terminal Tm-n in the same site as the acquired user terminal Tm-n. Saved by -n. Therefore, when the user terminal Tm-n that has acquired the content acquires content related to the content, it can be acquired from the user terminal Tm-n in the same base. This avoids concentration of content requests on the edge server SEm. Therefore, the load on the edge server SEm can be reduced, and content acquisition by the user terminal Tm-n can be performed smoothly.

  In each of the above embodiments, when the user terminal Tm-n acquires content from the edge server SEm at another base or the user terminal Tm-n at another base, the content is acquired via the edge server SEm in the same base. I was trying to do it. However, the edge server SEm in the same base may not be used. In this case, for example, when the user terminal Tm-n acquires content, the user terminal Tm-n transmits a notification message notifying the acquired content to the edge server SEm in the same base. The edge server SEm that has received the notification message acquires the related content of the notified content and transmits it to any user terminal Tm-n in the same site. Thereby, the content related to the content acquired by the user terminal Tm-n can be stored by any of the user terminals Tm-n in the same base.

  In each of the above embodiments, when the user terminal Tm-n acquires content from the user terminal Tm-n in the same base or the edge server SEm in the same base, the edge server SEm acquires the acquired content. The related content of was not acquired. However, even in this case, the edge server SEm may acquire the related content of the acquired content and store it in any user terminal Tm-n in the same base. This is effective when the related content of the content stored in the user terminal Tm-n or the edge server SEm is not necessarily stored in the user terminal Tm-n or the edge server SEm in the same base. is there. For example, when content is input, when the input server ST distributes content in advance to one or a plurality of nodes, or only content directly related to the content acquired by the user terminal Tm-n is stored in the same site. In some cases, the user terminal Tm-n stores the data.

  In each of the above embodiments, the peer-to-peer network using DHT is applied to the overlay network, but the present invention is not limited to this. For example, a system using another peer-to-peer network or an overlay network may be applied. As a peer-to-peer network that does not use DHT, for example, there is a hybrid peer-to-peer network.

11 Control unit 12 Storage unit 13 Communication unit 14 Bus 21, 41 Control unit 22, 42 Storage unit 23, 43 Buffer memory 24, 44 Decoder unit 25, 45 Video processing unit 26, 46 Display unit 27, 47 Audio processing unit 28, 48 Speaker 29, 49 Communication unit 30, 50 Input unit 31, 51 Bus ST Input server SEm Edge server Tm-n User terminal SM Management server SP Portal server MT Management terminal FW Firewall BR Broadband router Lm, LS Communication line NLm Base network NW Network NS Distribution Center Network PLm Base P2P Network PW, PW2 P2P Network S Content Distribution System

Claims (11)

An information communication system in which a plurality of contents are transmitted and received between a plurality of node devices,
The information communication system includes:
Multiple internal networks are connected to the external network,
A plurality of node devices connected to the same internal network;
A support device connected to the internal network and supporting content acquisition by the node device;
For each internal network,
The support device includes:
When the connection destination node device, which is the node device connected to the internal network of the connection destination, acquires content from any of the support devices or any of the node devices, the related content related to the content is Related content acquired from a non-connected support device that is the support device that is not connected to the internal network of the connection destination, or a related external node device that is the node device that is not connected to the internal network of the connection destination Acquisition means;
Related content transmission means for transmitting the related content acquired by the related content acquisition means to at least one of the connection destination node devices;
With
The node device is
Content acquisition means for acquiring content stored by the support device or another node device;
Related content receiving means for receiving the related content transmitted from the connection destination support device which is the support device connected to the internal network of the connection destination;
Storage means for storing the related content received by the related content receiving means;
An information communication system comprising: The information communication system according to claim 1,
The content acquisition unit of the node device acquires the content from the other node device connected to the internal network of the connection destination, and when the content cannot be acquired from the other node device, the out-of-connection support An information communication system, wherein content is acquired from a device or the disconnected node device. The information communication system according to claim 2,
The content acquisition unit of the node device acquires content from the connection destination support device when the content cannot be acquired from another node device connected to the internal network of the connection destination, and the connection destination support An information communication system comprising: acquiring content from the unconnected support device or the unconnected node device when content cannot be acquired from the device. The information communication system according to any one of claims 1 to 3,
The related content acquisition unit of the support device acquires the related content when the connection destination node device acquires content from the connection destination outside support device or the connection destination outside node device. Communications system. The information communication system according to claim 4,
The content acquisition unit of the node device includes:
Request information transmitting means for transmitting request information necessary for requesting content to the non-connected support device or the non-connected node device via the connection support device;
Content receiving means for receiving the content transmitted from the non-connection-destination support device or the non-connection-destination node device via the connection-destination support device;
With
The support device includes:
Relay means for relaying information transmitted / received between the connection destination node device and the connection destination outside support device or the connection destination outside node device;
Second storage means for storing content received from the non-connected support device or the non-connected node device by the relay means;
An information communication system, further comprising: The information communication system according to claim 5, wherein
If the content is stored in the second storage unit when the request information is received, the relay unit of the support apparatus stores the request information in the second storage unit without relaying the request information. An information communication system characterized by transmitting content to the connection destination node device that is the transmission source of the request information. In the information communication system according to claim 5 or 6,
The relay unit of the support device relays the request information when content is not stored in the second storage unit when the request information is received,
The related content acquisition unit of the support device acquires the related content related to the content received by the relay unit;
The information communication system, wherein the second storage unit stores the related content acquired by the related content acquisition unit. The information communication system according to any one of claims 1 to 7,
When the use bandwidth of information communication by the support device is equal to or less than a predetermined bandwidth, or when the processing load of the support device is equal to or less than a predetermined load, the related content acquisition unit of the support device An information communication system, wherein content is acquired, and the related content transmitting means of the support device transmits the related content. An information communication method in an information communication system in which a plurality of contents are transmitted and received between a plurality of node devices,
The information communication system includes:
Multiple internal networks are connected to the external network,
A plurality of node devices connected to the same internal network;
A support device connected to the internal network and supporting content acquisition by the node device;
For each internal network,
A content acquisition step in which the node device acquires content stored by the support device or another node device;
In the support device, the support device does not connect the related content related to the content acquired by the connection destination node device that is the node device connected to the connection destination internal network to the connection destination internal network. A related content acquisition step of acquiring from a connection destination external device that is a connection device outside the connection destination or the node device that is not connected to the internal network of the connection destination;
A related content transmission step in which the support device transmits the related content acquired in the related content acquisition step to at least one of the connection destination node devices;
A related content receiving step in which the node device receives the related content transmitted from a connection destination support device that is the support device connected to the internal network of a connection destination;
A storage step in which the node device stores the related content received in the related content receiving step;
An information communication method characterized by comprising: In an information communication system in which a plurality of contents are transmitted and received between a plurality of node devices, a support device that supports the content acquisition by the node devices,
The information communication system includes:
Multiple internal networks are connected to the external network,
A plurality of node devices connected to the same internal network;
The support device connected to the internal network;
For each internal network,
The support device includes:
When the connection destination node device, which is the node device connected to the internal network of the connection destination, acquires content from any of the support devices or any of the node devices, the related content related to the content is Related content acquired from a non-connected support device that is the support device that is not connected to the internal network of the connection destination, or a related external node device that is the node device that is not connected to the internal network of the connection destination Acquisition means;
Related content transmission means for transmitting the related content acquired by the related content acquisition means to at least one of the connection destination node devices;
A support device comprising: An information communication processing program in an information communication system in which a plurality of contents are transmitted and received between a plurality of node devices,
The information communication system includes:
Multiple internal networks are connected to the external network,
A plurality of node devices connected to the same internal network;
A support device connected to the internal network and supporting content acquisition by the node device;
For each internal network,
In the computer included in the support device,
When the connection destination node device, which is the node device connected to the internal network of the connection destination, acquires content from any of the support devices or any of the node devices, the related content related to the content is Related content acquired from a non-connected support device that is the support device that is not connected to the internal network of the connection destination, or a related external node device that is the node device that is not connected to the internal network of the connection destination An acquisition step;
A related content transmission step of transmitting the related content acquired by the related content acquisition means to at least one of the connection destination node devices;
An information communication processing program characterized in that

Images