JP2008236538A - Tree type broadcast system, method for broadcasting content, broadcast management apparatus, and broadcast management processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tree type broadcast system capable of reducing loads of a broadcast station and network loads. <P>SOLUTION: A content distributed storage system distributedly stores a plurality of content data in a plurality of node devices and allows each node to provide the stored content data through a network according to a request from another node device. A broadcast management apparatus in the tree type broadcast system in which the plurality of node devices are connected like a tree through a communication means while forming a plurality of hierarchies arranging a broadcast apparatus on the top position and the data broadcasted by the broadcast apparatus are sequentially transferred from the node device of the upper hierarchy to the node device of the lower hierarchy stores a broadcast list in which broadcast time is associated with information indicating the node device storing the content data, specifies the node information storing the content data to be broadcasted from the broadcast list and transmits instruction information for instructing broadcasting. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

In recent years, with the spread of broadband, content distribution services such as VOD (video on demand) have been provided. A peer-to-peer communication system has attracted attention as a new form that replaces the server-client system, which is the mainstream form of current content distribution. For example, a tree-type broadcast (distribution) system as disclosed in Patent Document 1 is proposed. Has been. In such a tree-type broadcasting system, a plurality of node devices are connected in a tree shape through communication means while forming a plurality of hierarchies with a broadcasting station (for example, a broadcasting server) at the top, and broadcasting ( Streamed content data is sequentially transferred from the upper layer node device to the lower layer node device.
JP 2006-33514 A

  By the way, a broadcasting station in such a tree-type broadcasting system needs to store content data to be broadcast in advance according to a predetermined broadcast schedule, and stores the content data when the content data to be broadcast increases. There is a problem that the storage capacity of the storage device for storage increases and the load (processing burden) of the broadcasting station also increases, and the equipment cost increases accordingly. There is also a problem that the load (network load) of the communication path between the broadcast station and each node device also increases.

  Therefore, the present invention has been made in view of the above problems and the like, and is a tree-type broadcast system, content broadcast method, broadcast management apparatus, and broadcast management process capable of reducing the load on the broadcast station and the network load. The challenge is to provide a program.

  In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a plurality of content data are distributed and stored in a plurality of node devices, and each of the node devices stores itself in response to a request from the other node device. A tree-type broadcasting system formed by participation of a plurality of node devices including all or part of the plurality of node devices in a content distributed storage system configured to provide the content data being provided via a network, A plurality of node devices are connected in a tree shape via communication means while forming a plurality of layers with the broadcasting device as the highest level, and content data broadcast by the broadcasting device is transferred from the node device of the upper layer to the lower layer Managing the broadcast of the content data in a tree-type broadcasting system that is sequentially transferred to the node device A transmission management device that stores a broadcast list in which broadcast time of the content data and node information indicating a node device that stores the content data on the content distributed storage system are associated with each other Indicated by the specified node information, node specifying means for specifying node information indicating the node device storing the content data to be broadcast when the broadcast time arrives, from the broadcast list, and Broadcast instruction information transmitting means for transmitting broadcast instruction information indicating an instruction to broadcast the content data as the broadcast device in the tree type broadcast system to the node device.

  According to the present invention, the broadcast list in which the broadcast time of the content data and the node information indicating the node device storing the content data on the content distributed storage system are stored in association with each other is stored. The node information indicating the node device storing the content data to be broadcast when the broadcast time arrives is identified from the broadcast list, and the node device indicated by the identified node information is Since the broadcast instruction information indicating an instruction to broadcast content data as the broadcasting device in the tree-type broadcasting system is transmitted, when the broadcast time arrives, the content can be quickly transmitted from the node device storing the content data. Data can be broadcast, and broadcasting devices are divided for each content data. It is possible, can require eliminated with collectively the content data to be broadcast to a particular station, thus, the load and the conventional broadcast stations, it is possible to reduce the network load.

  According to a second aspect of the present invention, in the broadcast management device according to the first aspect, the broadcast list includes broadcast times of a plurality of pieces of content data having different contents and node devices storing the respective content data. When the broadcast time for switching from the broadcast content data to the next content data has arrived, the node specifying means stores the next content data. Node information indicating the node device is specified from the broadcast list, and the broadcast instruction information transmitting means transmits the next content data to the tree for the next node device indicated by the specified node information. Broadcast instruction information indicating an instruction to broadcast as the broadcasting device in a type broadcasting system is transmitted.

  According to the present invention, when the broadcast time at which the content data being broadcast is switched to the next content data arrives, the next content data is quickly broadcast to the next node device as a broadcasting device in the tree-type broadcasting system. Can be made.

  According to a third aspect of the present invention, in the broadcast management device according to the second aspect, when the broadcast time at which the content data being broadcast is switched to the next content data has arrived, the broadcast device as the broadcast device It further comprises switching instruction information transmitting means for transmitting switching instruction information indicating an instruction to switch connection to the next node apparatus to a lower layer node apparatus connected to the node apparatus.

  According to the present invention, when the broadcast time at which the content data being broadcast is switched to the next content data arrives, the next node is connected to the node device in the lower hierarchy connected to the node device as the broadcast device. The connection to the device can be switched quickly.

  According to a fourth aspect of the present invention, in the broadcast management device according to any one of the first to third aspects, the content data whose broadcast time is described in the broadcast list is stored in the content distributed storage system. Search means for searching for a node device, and a node device capable of consuming the bandwidth required as the broadcasting device is selected from the searched node devices, and node information indicating the selected node device is selected as the content. Node selection description means described in the broadcast list in association with the broadcast time of the data.

  According to the present invention, the broadcasting device can be quickly searched from the content distributed storage system for each content data, and can be effectively used in the tree type broadcasting system.

  According to a fifth aspect of the present invention, in the broadcast management device according to any one of the first to fourth aspects, the content data whose broadcast time is described in the broadcast list is stored. Connection time information acquisition for acquiring connection time information indicating the connection time of each of the node devices to the network when the node information of the plurality of node devices is described in the broadcast list Means for comparing the connection times indicated in the acquired connection time information, and specifying the node information indicating the one node device based on the comparison result. Features.

  According to the present invention, a more stable tree type broadcasting system can be formed.

  The invention of a broadcast management processing program according to claim 6 is characterized in that it functions as the broadcast management device according to any one of claims 1 to 5.

  According to the seventh aspect of the present invention, a plurality of content data are distributed and stored in a plurality of node devices, and each node device stores content data stored by itself in response to a request from another node device. A tree-type broadcast system that includes all or part of the plurality of node devices in the distributed content storage system provided through the participation of the plurality of node devices, and the plurality of node devices serve as broadcasting devices. A plurality of hierarchies are formed as the highest level, connected in a tree shape via communication means, and content data broadcast by the broadcasting device is sequentially transferred from the node device in the upper layer to the node device in the lower layer In the above-described tree-type broadcast system, the broadcast management apparatus that manages the broadcast of the content data has the above-described configuration. Storage means for storing a broadcast list in which the broadcast time of the content data and node information indicating the node device storing the content data on the content distributed storage system are associated with each other, and the broadcast time Node identification means for identifying node information indicating the node device storing content data to be broadcast upon arrival from the broadcast list, and the content for the node device indicated in the identified node information Broadcast instruction information transmitting means for transmitting broadcast instruction information indicating an instruction to broadcast data as the broadcast device in the tree-type broadcast system, and the node device that has received the broadcast instruction information receives the broadcast instruction information. According to the content data stored by the self, connected to the self Characterized in that it comprises a broadcasting means for broadcasting to the node device in the lower hierarchy.

  According to an eighth aspect of the present invention, a plurality of content data are distributed and stored in a plurality of node devices, and each node device stores content data stored by itself in response to a request from the other node devices. A tree-type broadcast system that includes all or part of the plurality of node devices in the distributed content storage system provided through the participation of the plurality of node devices, and the plurality of node devices serve as broadcasting devices. A plurality of hierarchies are formed as the highest level, connected in a tree shape via communication means, and content data broadcast by the broadcasting device is sequentially transferred from the node device in the upper layer to the node device in the lower layer A content broadcasting method in a tree-type broadcasting system configured to manage broadcasting of the content data A broadcast management device stores a broadcast list in which a broadcast time of the content data and node information indicating a node device that stores the content data on the content distributed storage system are associated with each other, Node information indicating the node device that stores the content data to be broadcast when the broadcast time arrives is identified from the broadcast list, and the content is determined for the node device indicated by the identified node information. Broadcast instruction information indicating an instruction to broadcast data as the broadcasting device in the tree-type broadcasting system, the node device receives the broadcast instruction information, and stores the broadcast instruction information according to the received broadcast instruction information; The content data is released to the lower-level node device connected to itself. Characterized in that it.

  According to the present invention, the broadcast list in which the broadcast time of the content data and the node information indicating the node device storing the content data on the content distributed storage system are stored in association with each other is stored. The node information indicating the node device storing the content data to be broadcast when the broadcast time arrives is identified from the broadcast list, and the node device indicated by the identified node information is Since the broadcast instruction information indicating an instruction to broadcast content data as the broadcasting device in the tree-type broadcasting system is transmitted, when the broadcast time arrives, the content can be quickly transmitted from the node device storing the content data. Data can be broadcast, and broadcasting devices are divided for each content data Since bets can, can require eliminated with collectively the content data to be broadcast to a particular station, thus, the load and the conventional broadcast stations, it is possible to reduce the network load.

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

[ 1. Configuration of communication system ]
First, a schematic configuration and the like of the communication system according to the present embodiment will be described with reference to FIG.

  FIG. 1 is a diagram illustrating an example of a connection mode of each node device in the communication system according to the present embodiment.

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

  A plurality of node devices (hereinafter referred to as “nodes”) Nn (n = 1, 2, 3,...) Are connected to such a network 8. Each node Nn is assigned a unique manufacturing number and an IP (Internet Protocol) address. Such serial numbers and IP addresses are not duplicated among a plurality of nodes.

  The communication system S according to the present embodiment is a peer-to-peer network system formed by participation of any one of the nodes Nn among the nodes Nn, as shown in the upper frame 100 of FIG. ing. A network 9 shown in the upper frame 100 of FIG. 1 is an overlay network 9 (logical network) that forms a virtual link formed using the existing network 8.

  Further, the communication system S is a composite system of a content distribution (type) storage system and a tree type broadcast system (also referred to as a tree type content distribution system).

  FIG. 2 is a conceptual diagram of the communication system S according to the present embodiment.

  In FIG. 2, the content distributed storage system SX1 stores a plurality of pieces of content data (actually, duplicate data (replica) that is a copy of the content data) in a plurality of nodes Nn (for example, nodes N1, N3, and N5). ), And each node Nn (for example, node N1) provides content data stored by itself in response to a request from another node Nn (for example, node N2) via the network 8. It is possible.

  On the other hand, the tree broadcast system SX2 includes all or a part of a plurality of (participating) nodes Nn in the content distributed storage system SX1 (in the example of FIG. 2, among the nodes Nn in the content distributed storage system SX1) N10, node N1, and node N11), and formed by the participation of a plurality of nodes Nn. The plurality of nodes Nn form a plurality of hierarchies with the node N10 as a broadcasting device as the highest level. On the other hand, the content data connected in a tree shape via the network 8 and broadcast (streamed) by the node N10 is transferred from the upper layer node Nn (for example, the node N1) to the lower layer node Nn (for example, the node N12). ) Are sequentially transferred.

  As described above, in the tree broadcast system SX2 according to the present embodiment, it is assumed that the node Nn storing the content data to be broadcast in the content distributed storage system SX1 operates as the highest-level broadcast device (broadcast station). It is said.

[ 1-1. Configuration and Function of Content Distributed Storage System SX1 ]
Next, the content distributed storage system SX1 will be described in detail.

  The content distributed storage system SX1 is realized by a specific algorithm, for example, an algorithm using a DHT (Distributed Hash Table).

  Each node Nn participating in the content distributed storage system SX1 is assigned a node ID, which is unique identification information. The node ID is, for example, an IP address individually assigned to each node Nn. Alternatively, it is a value obtained by hashing the production number with a common hash function (for example, SHA-1 or the like) (for example, the bit length is 160 bits), and is distributed without being distributed in one ID space as shown in FIG. Will be.

  In addition, participation in the content distributed storage system SX1 is performed when any node Nn (for example, the node N8) that has not participated participates in any node Nn (for example, a contact node that always participates in the system SX1). This is done by sending a participation message indicating a participation request.

  As described above, the node ID obtained (hashed) by the common hash function has a very low probability of having the same value if the IP address or the manufacturing number is different. The node ID needs to have a number of bits that can accommodate the maximum number of nodes that can be operated. For example, if a 128-bit number is used, 2 ^ 128 = 340 × 10 ^ 36 nodes can be operated. Since the hash function is publicly known, detailed description thereof is omitted.

  Each node Nn holds a routing table using DHT. This routing table defines the transfer destinations of various messages on the content distributed storage system SX1, and specifically, a node including the node ID, IP address, and port number of the node Nn that is moderately separated in the ID space A plurality of pieces of information (transfer destination node information) are registered.

  One node Nn participating in the content distributed storage system SX1 registers in the routing table the node information of the minimum necessary node Nn among all the nodes Nn participating in the system SX1, With respect to the node Nn that does not know (store) the node information, various messages are transferred between the nodes Nn to be delivered.

  Here, the routing table using DHT will be described in detail with reference to FIGS. 3 and 4.

  FIG. 3 is a diagram illustrating an example of a routing table using the DHT held by the node N2, and FIG. 4 is a conceptual diagram illustrating an example of an ID space of the DHT.

  3 and 4, for convenience of explanation, the bit length of the node ID is 2 bits × 3 digits = 6 bits, and each digit is represented by a quaternary number (an integer of 0 to 3) (actually, A longer bit length is used, and each digit is also divided into, for example, 4 bits and expressed by a hexadecimal number of 0 to f).

  In the example of FIG. 3, the routing table using DHT is composed of level 1 to level 3 tables (divided into a plurality of levels), and each level table entry includes node information for each area. The node ID is registered in association with the IP address and port number of the node Nn corresponding to the node ID. Each area in the table of each level is an area obtained by dividing the DHT node ID space. For example, as shown in FIG. 4, in the level 1, the entire ID space of the DHT is divided into four, the area where the node IDs “000” to “033” are present is the 0XX area, and “100” to “133”. The area where the node ID exists is the 1XX area, the area where the node IDs “200” to “233” exist are the 2XX area, and the area where the node IDs “300” to “333” exist are the 3XX area. . In level 2, the area of level 1 (that is, the area from 0XX to 3XX) is further divided into four, for example, the area of 1XX is divided into four, and the area where the node IDs “100” to “103” exist is 10X. Area, an area where node IDs “110” to “113” exist are 11X areas, an area where node IDs “120” to “123” exist are 12X areas, and node IDs “130” to “133” exist The area in which is present is defined as a 13X area.

  For example, if the node ID of the node N2 is “122”, as shown in FIG. 3, the table of the 1XX area at the level 1 of the node N2 (the area where the self (that is, the own node) exists) The area where the self node ID and IP address (the IP address is own, so it is not necessary to register it in the routing table) etc. is registered and does not exist (that is, 0XX area, 2XX area) , And 3XX area), node IDs and IP addresses of other arbitrary nodes Nn are registered.

  In addition, in the table of the 12X area (the area where the self exists) in the level 2 of the node N2, as shown in FIG. 3, the self node ID and the IP address (the IP address is own) In the areas where the self does not exist (that is, the 10X area, the 11X area, and the 13X area), etc., nodes of other arbitrary nodes Nn, respectively, are registered. ID, IP address, etc. are registered.

  Further, in the level 3 of the node N2, as shown in FIG. 3, the node IDs and IP addresses having node IDs “120” to “122” are registered in the routing table. Is not necessary).

  In the examples of FIGS. 3 and 4, since the bit length of the node ID is 3 digits × 2 bits, it can be covered with a table for three levels of levels 1 to 3. However, if the bit length of the node ID increases, (For example, if the bit length of the node ID is 16 digits × 4 bits, a table for 16 levels is required).

  Thus, in the routing table using DHT in the present embodiment, the area becomes narrower as the level increases.

  Such DHT is given, for example, when a non-participating node participates in the content distributed storage system SX1.

  By the way, in the content distributed storage system SX1, various content (for example, movies, music, etc.) data is distributed and stored (stored) in a plurality of nodes Nn (in other words, a replica in which content data is duplicated). Distributed).

  For example, the content data of a movie whose title is ABC (hereinafter referred to as “content ABC”) is stored in the node N1 and the node N5, and the content data of a movie whose title is XXX (hereinafter referred to as “content”) is stored in the node N10 and the like. XXX ”and the content data of the movie whose title is YYY (hereinafter referred to as“ content YYY ”) are stored in the node N3 and the like. Are distributed and stored.

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

  Further, the location of the content data thus distributed and stored, that is, node information (for example, including an IP address and a port number) indicating the node Nn storing the content data, and a content ID corresponding to the content data Index information including a group such as a node Nn (hereinafter referred to as a “root node”) as a management source of the location of the content data (that is, a node Nn that manages node information of the node Nn that can transmit the content data) Alternatively, it is stored (stored in the index cache) and managed by “content (content ID) root node”) or the like.

  For example, the index information of the content ABC is managed by the node N4 that is the root node of the content (content ID), and the index information of the content XXX is managed by the node N6 that is the root node of the content (content ID). . That is, since the root node is divided for each content, load distribution is achieved, and even if the same content data (content ID is the same) is stored in a plurality of content holding nodes, The index information of such content data can be managed by one root node.

  Further, such a root node is determined to be, for example, a node Nn having a node ID closest to the content ID (for example, the higher-order digits match more).

  When a user of a certain node Nn wants to acquire desired content data, a node Nn (hereinafter referred to as a “user node”) from which the content data is desired to be acquired is selected by the user (for example, to all the nodes Nn). Content ID of content data and its own node information that have been distributed (selected from, for example, a content management server (not shown)) in which content catalog information is distributed (content name, content ID, etc. are described) A content location inquiry (search) message (query) including is generated and sent to another node Nn according to a routing table using its own DHT. That is, the user node sends a content location inquiry (search) message to the root node (to the root node). As a result, the content location inquiry (search) message finally arrives at the root node by DHT routing using the content ID as a key.

  The content ID included in the content location inquiry (search) message may be generated by the user node by hashing the content name with the common hash function.

  FIG. 5 is a conceptual diagram showing an example of the flow of a content location inquiry (search) message sent from a user node in the DHT ID space.

  In the example of FIG. 5, for example, the node N2, which is a user node, refers to the DHT level 1 table and is closest to the content ID included in the content location inquiry (search) message (for example, the upper digit is For example, an IP address and a port number included in the node information of the node N3 having a node ID that more matches) are acquired, and the content location inquiry (search) message is transmitted to the IP address and the port number.

  On the other hand, the node N3 receives the content location inquiry (search) message, refers to the DHT level 2 table, and is closest to the content ID included in the content location inquiry (search) message. The IP address and port number included in the node information of, for example, the node N4 having a node ID (for example, the higher digit matches more) are acquired, and the content location inquiry (search) message is addressed to the IP address and port number. Forward.

  On the other hand, the node N4 receives the content location inquiry (search) message, refers to the table of the level 3 of its own DHT, and is closest to the content ID included in the content location inquiry (search) message. If the node ID (for example, the higher-order digits match more) is itself, that is, if it recognizes that it is the root node of the content ID, it corresponds to the content ID included in the content location inquiry (search) message The index information to be acquired is acquired from the index cache, and the index information is returned to the user node that is the transmission source of the content location inquiry message. As a result, the user node transmits a content transmission request message (request information indicating a content data transmission request) to, for example, the node N1, which is the content holding node storing the desired content data, and from there It becomes possible to receive provision of the content data.

  Alternatively, the node N4 that is the root node sends a content transmission request message (including node information of the user node to the content holding node indicated in the node information included in the index information, and transmits content data to the user node. Request information indicating a transmission request).

  As a result, the user node can receive the content data from the content holding node, for example, the node N1.

  The user node obtains the index information from the relay node that caches the same index information as the root node (for example, the cache node of the node N3) until the content location inquiry message reaches the root node. It can also be acquired (received).

  By the way, for content data in which the number of content data that is distributed and stored is small (the number of content holding nodes that store replicas is small), the user node sends a content location inquiry (search) message to another node Nn. Even if it is sent to the content node, if the response (the above index information) cannot be obtained quickly from the root node (for example, it takes a long time for the response or the response does not return) The content data may not be acquired quickly due to concentration of access to the Internet. In such a case, the user node can also access the content management server that manages all the content data and acquire the content data. However, in order to avoid load concentration of the content management server, ideally, it is desirable to exchange content data between the nodes Nn.

  The user node that has acquired and saved the content data as described above notifies the root node that the content data has been saved (in other words, the system holds that the user node holds the content data. Publish (registration notification) message containing the content ID of the content data, its own node information, etc. (to save the content data, so that it can be disclosed to other nodes Nn participating in SX1) And a publish message is sent out to the root node. As a result, the publish message arrives at the root node by DHT routing using the content ID as a key in the same manner as the content location inquiry (search) message, and the root node is a node included in the received publish message. Index information including a set of information and content ID is registered (stored in the index cache area). Thus, the user node becomes a new content holding node that holds the content data.

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

[ 1-2. Configuration and function of tree-type broadcasting system SX2 ]
Next, the tree type broadcast system SX2 will be described in detail.

  In the tree-type broadcasting system SX2, content data is distributed in a streaming manner from a node Nn (for example, the node N10 shown in FIG. 2) that is a broadcasting device (broadcasting station), and the node Nn in the upper hierarchy to the node Nn in the lower hierarchy. Sequential transfer (in each node Nn on the way route), each packet of the received content data is buffered and transferred to the node Nn in the lower layer, and is reproduced in each node Nn.

  The connection mode (topology) between the nodes Nn in the tree-type broadcast system SX2 is managed by the broadcast management server 10 (an example of a broadcast management apparatus that manages content data broadcasting of the present invention). The broadcast management server 10 controls the broadcast of content data in the system SX2 (in other words, the broadcast control function 10a for controlling the broadcast by the node Nn as the highest-level broadcast device) and the connection destination in the system SX2. And an introduction function 10b introduced to the node Nn. The introduction function 10b may be realized by another server.

  FIG. 6 is a diagram illustrating a schematic configuration example of the broadcast management server 10.

  As shown in FIG. 6, the broadcast management server 10 includes a control unit 101 as a computer composed of a CPU having a calculation function, a working RAM, a ROM for storing various data and programs, and various data (for example, content Data, index information, DHT, etc.) and information storage control between the storage unit 102 as a storage means composed of an HD etc. for storing (storing) various programs, etc., and the node Nn through the network 8. And a communication unit 103 for performing communication. The control unit 101, the storage unit 102, and the communication unit 103 are connected to each other via a bus 104.

  The storage unit 102 includes node information (for example, IP address and port number) indicating each node Nn participating in the tree-type broadcast system SX2, connection mode information indicating a connection mode (topology) between the nodes Nn, In addition, a broadcast list (broadcast list database) that defines a broadcast schedule of content data to be broadcast in the tree-type broadcast system SX2 is stored.

  Here, the connection mode information includes (i) the hierarchy in which each node Nn is located in the hierarchical structure in the tree type broadcast system SX2 (for example, the nodes N1 and N15 shown in FIG. 2 are in the first hierarchy, the nodes N11 and N16, etc. Are located in the third hierarchy), and (ii) nodes Nn (for example, the node N10 shown in FIG. 2 include nodes N1 and N15) connected as a lower hierarchy of each node Nn. Lower device information indicating (connected as a lower hierarchy), and (iii) allowable connection number information indicating the allowable connection number of nodes Nn connectable as a lower hierarchy of each node Nn (tree-type broadcast system SX2 shown in FIG. 2) (Iv) 3 or more may be used), and (iv) transfer capability information (example) indicating transfer capability of each node Nn to transfer content data to another node Nn If the node CPU processing speed (MHz) or effective bandwidth in the network 8 of Nn (e.g., data rate (bps)) and are included.

  In the broadcast list, the content name (title) of the content data to be broadcast, the broadcast time, the content holding node storing the content data and the node Nn (hereinafter referred to as a broadcast device candidate) Node information indicating "broadcast node candidate" and node information indicating a node Nn (hereinafter referred to as "broadcast node") serving as a broadcast device selected from the broadcast node candidates for each content data (different contents) Are described in association with each other.

  FIG. 7 is a conceptual diagram showing the contents of the broadcast list. In the example of FIG. 7, the content XXX, the content YYY, and the content ZZZ are broadcast in the order of broadcasting. The broadcast nodes of the content XXX are the node N10, the node N15 that are broadcast node candidates, and the content The node N10 is selected from the pool (the content management server described above or the broadcast server of the conventional broadcast station), and the node of the content node YYY and the content pool are selected as the broadcast node for the content YYY. Since N3 is selected and there is no candidate as a broadcast node for the content ZZZ, a content pool (lowest priority) is unavoidably selected.

  Note that the broadcast order of the content data defined by the broadcast list is determined based on, for example, the popularity ranking information of content in the content distributed storage system SX1 (that is, the higher the popularity, the higher the broadcast order). For example, the popularity ranking information is created by a predetermined server that collects the number of requests for content data aggregated by the root node of each content data (in other words, the number of times index information has been transmitted to the user node) (number of requests). The more it is, the more popular it is. Alternatively, when the content data stored in the content distributed storage system SX1 is encrypted with a predetermined content key, the user node requests the key server for the content key to decrypt the acquired content data. The content key provided from the key server is acquired, but the key server may be configured to create popularity ranking information by counting the number of times the content key is provided for each content data. .

  The broadcast list includes a broadcast content list in which a broadcast order, a content name (title) of content data to be broadcast, and a broadcast time are described, node information indicating the broadcast order and a broadcast node candidate of the content data, and It may be managed separately in a broadcast node list in which broadcast nodes are described.

  In the configuration of the broadcast management server 10 described above, the control unit 101 performs overall control by the CPU reading and executing a program (including the broadcast management processing program of the present invention) stored in the storage unit 102 or the like. A connection destination introduction process for introducing a connection destination in response to a participation message from each node Nn is performed. Furthermore, the control unit 101 functions as a node specifying unit, a broadcast instruction information transmitting unit, a switching instruction information transmitting unit, a searching unit, a node selection description unit, a connection time information acquiring unit, and the like according to the present invention, and performs processing described later. It is like that. The broadcast management processing program may be downloaded from a predetermined server on the network 8, for example, or recorded on a recording medium such as a CD-ROM and via a drive of the recording medium. It may be read.

  Specifically, when receiving the participation message from the node Nn, the control unit 101 refers to the connection mode information and the broadcast list, and selects the node Nn to be connected to the node Nn. The control unit 101 transmits a connection destination introduction message including the node information of the selected node Nn and the hierarchy information of the selected node Nn to the node Nn via the communication unit 103 or the like (introducing the connection destination). It is like that. For example, the control unit 101 identifies a node Nn in which the number of nodes Nn connected as a lower hierarchy is less than the allowable number of connections based on the connection mode information (for example, prioritizes a node Nn located in a higher hierarchy) ) When there are a plurality of identified nodes Nn, the control unit 101 identifies, for example, one node Nn having the highest transfer capability from these nodes Nn (even if one node Rn is identified randomly from these nodes Nn). This is good), and this is selected as the node Nn to be connected. The control unit 101 obtains the node information of the selected node Nn from the connection mode information, includes this in the connection destination introduction message, and returns it to the node Nn that is the transmission source of the participation message. When the connection destination is the highest broadcast node, the node information of the broadcast node at the current time described in the broadcast list is acquired and included in the connection destination introduction message, and the node from which the participation message is transmitted A reply is made to Nn (because the broadcast node changes with time).

  In addition, the control unit 101 specifies node information indicating a broadcast node storing content data to be broadcast when the broadcast time (the latest broadcast time closest to the current time) arrives from the broadcast list. The control unit 101 sends a broadcast start instruction message (indicating the content data) that is broadcast instruction information indicating an instruction to broadcast the content data as a broadcast device in the tree type broadcast system SX2 to the broadcast node indicated by the identified node information. (Including content ID and content name) is transmitted via the communication unit 103 or the like. Thereby, the broadcast node that has received the broadcast start instruction message broadcasts the content data to the node Nn connected to the lower layer.

  Also, broadcast node candidates (content pools are described in advance without searching) corresponding to each content name described in the broadcast list are searched from the content distributed storage system SX1. For example, the control unit 101 generates a content location inquiry (search) message (query) including a content ID corresponding to content data to be described in the broadcast list and its own node information, and the message is set in advance, for example. It is sent to an arbitrary node Nn via the communication unit 103 or the like (that is, the broadcast management server 10 sends a content location inquiry (search) message toward the root node (to the root node)). Thereby, the content location inquiry (search) message finally arrives at the root node by DHT routing using the content ID as a key, and the broadcast management server 10 is included in the content location inquiry (search) message from the root node. Index information corresponding to the content ID is acquired. Node information of the content holding node thus searched (that is, the content holding node described in the acquired index information) is associated with the broadcast time of the content data as the node information of the broadcast node candidate, and the broadcast list. Will be described.

  However, in order for the content holding node to become a broadcasting device, it is necessary to be able to consume the bandwidth required for the broadcasting device, so the control unit 101 uses the required bandwidth for each searched content holding node as described above. A content holding node satisfying a band (preset) (that is, a content holding node that can consume a band required as a broadcasting device) is selected as a broadcast node candidate, and the node information is described in the broadcast list. Note that the effective bandwidth of each content holding node is determined from, for example, the data transmission speed at the time when predetermined data is transmitted and received between the broadcast management server 10 and the content holding node. Alternatively, the broadcast management server 10 may acquire an effective band obtained by transmitting / receiving predetermined data between another server and the content holding node.

  Further, for example, when a plurality of broadcast node candidates are described in a broadcast list for one piece of content data as in the content XXX shown in FIG. 7, one of the broadcast node candidates is set as a broadcast node. The control unit 101 compares, for example, the connection time of each broadcast node candidate to the network 8 (the energization time in the case of participating in the content distributed storage system SX1 by turning on the power) Based on the comparison result, for example, the broadcast node candidate with the longest connection time is selected as the broadcast node. This is because the node Nn having a long connection time can be expected to participate continuously without turning off the power from now on, so that the content data can be broadcast stably. Alternatively, the broadcast node candidate with the shortest connection time may be selected as the broadcast node, and this is because the node Nn that has just joined the content distributed storage system SX1 continues without turning off the power immediately. This is because you can expect to participate. Connection time information indicating the connection time of each broadcast node candidate to the network 8 is acquired from each broadcast node candidate.

  When the broadcast time for switching from the currently broadcast content data to the next content data has arrived, the control unit 101 identifies from the broadcast list node information indicating the broadcast node storing the next content data. Then, a broadcast start instruction message indicating an instruction to broadcast the next content data as a broadcast device in the tree type broadcast system SX2 is transmitted to the broadcast node indicated by the identified node information via the communication unit 103 or the like. At this time, the control unit 11 switches a switching instruction message (next broadcasting node) as switching instruction information indicating an instruction to switch the connection to the next broadcasting node for the lower layer node Nn currently connected to the broadcasting node. Is transmitted via the communication unit 103 or the like.

  FIG. 8 is a diagram illustrating a state when the broadcast node is switched.

  In the example of FIG. 8, since the broadcast of the content XXX is switched to the broadcast of the content YYY, the node N1 and the node N15 that are connected to the node N10 that is the broadcast node of the content XXX are switched from the broadcast management server 10. Is switched from node N10 to node N3 (broadcast node for content YYY). The node Nn in the lower hierarchy (second hierarchy or lower) of the node N1 or the node N15 does not need to switch the connection destination.

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

  FIG. 9 is a diagram illustrating a schematic configuration example of the node Nn.

  As shown in FIG. 9, each node Nn 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 various data (for example, content data). , Index information, DHT, etc.) and a storage unit 12 composed of an HD etc. for storing and storing (storing) various programs, etc., a buffer memory 13 for temporarily storing received content data, etc., and included in the content data A decoder unit 14 that decodes (decompresses and decodes) encoded video data (video information) and audio data (audio information), and performs a predetermined drawing process on the decoded video data and the like. The video processing unit 15 that outputs as a video signal, and the video processing unit 15 that outputs the video signal A display unit 16 such as a CRT or a liquid crystal display for displaying an image based on the video signal, and the decoded audio data is converted into an analog audio signal by D (Digital) / A (Analog) and then amplified by an amplifier and output. In order to control communication of information between the audio processing unit 17, the speaker 18 that outputs the audio signal output from the audio processing unit 17 as a sound wave, and another node Nn, the broadcast management server 10, and the like through the network 8. Communication unit 20 and an input unit 21 (for example, a keyboard, a mouse, or an operation panel) that receives an instruction from the user and gives an instruction signal corresponding to the instruction to the control unit 11. The control unit 11, the storage unit 12, the buffer memory 13, the decoder unit 14, the communication unit 20, and the input unit 21 are connected via a bus 22. And connected to each other. As the node Nn, a personal computer, an STB (Set Top Box), a TV receiver, or the like can be applied. The storage unit 12 also has an IP address and port number of a contact node that is an access destination when participating in the distributed content storage system SX1, and a broadcast management server 10 that is an access destination when participating in the tree-type broadcast system SX2. IP address and port number are stored.

  In such a configuration, the control unit 11 reads and executes a program stored in the storage unit 12 or the like, so that the overall control is performed, and the above-described user nodes by participating in the content distributed storage system SX1 Processing as at least one of a relay node, a root node, a cache node, and a content holding node is performed.

  Each node Nn is distributed in advance with a broadcast schedule table (in other words, a broadcast program table) in which the content name, broadcast time, outline, etc. of each content data described in the broadcast list are described. The table is displayed on the display unit 16 according to an instruction from the user via the input unit 21. Then, when the user views the broadcast schedule table and operates the input unit 21 to give an instruction to participate in the tree-type broadcast system SX2, the control unit 11 sends the participation message described above to the broadcast management server 10 as a communication unit. 20 etc. will be transmitted. And the said control part 11 should receive the connection destination introduction message from the broadcast management server 10 via the communication part 20, and should become a self upper layer based on the node information shown by the said connection destination introduction message. A connection with a node Nn is established, and a content data transfer request is made to the node Nn.

  In this way, in the node Nn participating in the tree-type broadcasting system SX2, each packet of content data transferred (distributed) from the connected upper layer node Nn is received and buffered, while the decoder unit 14, Reproduction processing is performed through the video processing unit 15, the display unit 16, the audio processing unit 17, and the speaker 18, and when there is a lower layer node Nn, the content data is transferred to the node Nn. .

  Each node Nn not only participates in the tree-type broadcasting system SX2 for the first time, but also when the node quits the system SX2 due to power-off or communication failure, and then rejoins the system SX2, or Even when the upper layer node Nn is disconnected from the system SX2 or the transfer of content data is interrupted, the participation message is transmitted to the broadcast management server 10 and the connection destination introduction message is acquired from the broadcast management server 10. Will do.

  Further, when the control unit 11 receives a broadcast start instruction message from the broadcast management server 10, the control unit 11 reads out the content data indicated by the broadcast start instruction message from the storage unit 12, and connects this as its own lower layer. Broadcasting (stream distribution) is performed to the node Nn (which has requested transfer of content data).

  In addition, when receiving the switching instruction message from the broadcast management server 10, the control unit 11 establishes a connection with the broadcasting node based on the node information of the broadcasting node indicated by the switching instruction message, and the content data And a connection with the previous broadcast node is disconnected (connection switching).

[ 3. Operation of tree-type broadcasting system SX2 ]
Next, the operation of the communication system S in the present embodiment will be described with reference to FIGS.

  FIG. 10A is a flowchart showing broadcast list generation processing in the control unit 101 of the broadcast management server 10, and FIG. 10B is a flowchart showing bandwidth determination processing in the control unit 11 of the content holding node. FIG. 11 is a flowchart showing connection destination introduction processing in the control unit 101 of the broadcast management server 10. 12 is a flowchart showing the broadcast node switching process in the control unit 101 of the broadcast management server 10, and FIG. 13 shows the exchange between the broadcast management server 10 and the node Nn in time series when the broadcast node is switched. FIG.

(Broadcast list generation processing)
First, in the broadcast list generation process shown in FIG. 10A, for example, when the broadcast management server 10 receives the popularity ranking information transmitted from a predetermined server that has created (periodically created) the popularity ranking information described above, for example. The control unit 101 selects content data to be broadcast based on the popularity ranking information (for example, up to the top 20), and determines their broadcast order (for example, popularity ranking order) (step S1). S1). Note that the content data to be broadcast and the broadcast order may be performed by the server that created the popularity ranking information. When the broadcast list is divided into a broadcast content list and a broadcast node list, a broadcast content list is generated based on popularity ranking information in a predetermined server, and the broadcast content list is received from the predetermined server. Broadcast list generation processing shown in FIG. 10 (A) is started.

  Next, the control unit 101 performs a search process for a content holding node that stores the selected content data (step S2). In the search process of the content holding node, the control unit 101, for example, a content location inquiry (search) including a content ID corresponding to the selected content data (or content data whose content name is described in the broadcast content list). As described above, the message (query) is transmitted to the root node, and the transmitted index information from the root node is received. Note that the content holding node search process is performed for each selected content data.

  Next, the control unit 101 makes a bandwidth determination request to the content holding node whose node information is described in the received index information (transmits a bandwidth determination request message indicating a bandwidth determination request based on the node information) (step S3). ). The bandwidth determination request is made for each of the selected content data (when a plurality of content holding nodes are searched for one content data, the bandwidth determination request is made for all these content holding nodes. ).

  On the other hand, when the content holding node receives a bandwidth determination request from the broadcast management server 10 (when receiving the bandwidth determination request message), the content holding node starts the bandwidth determination processing shown in FIG. A determination is made (step S11). For example, the content holding node transmits and receives predetermined data between itself and the broadcast management server 10 (or another server) and measures the effective bandwidth.

  Next, the control unit 11 determines whether or not the determined band (measured effective band) satisfies the consumption band required for the broadcasting device (step S12), and if so (step S12: YES). ) A response message indicating that the consumed bandwidth is satisfied is returned to the broadcast management server 10 (step S13). If not satisfied (step S12: NO), it indicates that the consumed bandwidth is not satisfied. The response message is returned to the broadcast management server 10 (step S14), and the process is terminated.

  On the other hand, the broadcast management server 10 receives the response message thus transmitted from the content holding node (step S4).

  When such a response message is received from all the content holding nodes requested to determine the bandwidth, the control unit 11 then transmits a response message indicating that the consumed bandwidth is satisfied for each content data. The content holding node thus selected is selected as a broadcast node candidate (step S5).

  Next, the control unit 11 selects, for each content data, one broadcast node having the highest priority from among the broadcast node candidates according to a preset selection criterion (step S6). For example, as described above, a broadcast node having a long (or short) connection time is preferentially selected based on the connection time to the network 8 or the like. The broadcast node may be selected immediately before the broadcast time (broadcast start time) of the content data arrives. This is because if the time from the selection to the broadcast time is long, the selected broadcast node is withdrawn from the tree-type broadcast system SX2 or the priority is changed in the meantime.

  Next, the control unit 11 generates a broadcast list in which the content name and broadcast time for each selected content data to be broadcasted and the selected broadcast node candidate and the node information of the broadcast node are described (determined above) (According to the broadcast order) (step S7), the previously generated and stored broadcast list is updated (difference is updated) (step S8), and the process ends. When the broadcast list is divided into a broadcast content list and a broadcast node list, the broadcast node list in which the broadcast order, node information indicating candidate broadcast nodes of the content data, and the broadcast node are described is generated in the process of step S7. It will be.

(Connection introduction process)
Next, the connection destination introduction process shown in FIG. 11 is started when the broadcast management server 10 receives the participation message transmitted from the node Nn, and the control unit 101 refers to the connection mode information and the broadcast list. As described above, the node Nn to be connected to the node Nn is selected (step S21).

  Next, the control unit 101 determines whether or not the selected connection destination is a broadcast node (introducing a broadcast node as a connection destination) (step S22). If the connection destination is not a broadcast node (step S22: NO) ), A connection destination introduction message including the node information of the selected connection destination node Nn is transmitted to the node Nn (introduction of the connection destination) (step S23), and the processing ends. On the other hand, when the selected connection destination is a broadcast node (step S22: YES), the control unit 101 refers to the broadcast list (step S24), for example, a broadcast node (or a broadcast node of content data currently being broadcast) (or Node information of the next broadcast node of content data to be broadcast is acquired from the broadcast list (step S25), and a connection destination introduction message including the node information of the broadcast node is transmitted to the node Nn (the connection destination is set). (Introduction) (step S26), and the process ends.

  The node Nn that has received the connection destination introduction message transmitted in this way establishes a connection with the node Nn that should be its own upper layer based on the node information indicated in the connection destination introduction message, and A content data transfer request is made to Nn.

(Broadcast node switching processing)
Next, the broadcast node switching process shown in FIG. 12 is started when the broadcast time at which the content data currently broadcast from a certain broadcast node is switched to the next content data has arrived (actually just before), The control unit 101 refers to the broadcast list, identifies the current broadcast node and the next broadcast node, and acquires node information of the identified current broadcast node and the next broadcast node, as shown in FIG. Furthermore, referring to the connection mode information, the first layer node Nn connected to the current broadcast node is specified, and the node information of the specified node Nn is acquired (step S31).

  Next, the control unit 101 transmits a broadcast end instruction message indicating an instruction to end the broadcast of the content data to the current broadcast node according to the specified node information (step S32A), and to the next broadcast node. Then, a broadcast start instruction message indicating an instruction to start broadcasting content data is transmitted (step S32B), and an instruction to switch the connection to the next broadcast node to the first layer node Nn (subordinate node of the broadcast node) is sent. A switching instruction message is transmitted (step S32C), and the process ends. As a result, the first layer node Nn switches the connection of the broadcast node, and the next broadcast node broadcasts the content data stored therein to the first layer node Nn. Thus, by simultaneously issuing three events (message transmission) asynchronously, for example, the broadcast node can be switched without interruption of video distribution. Since the broadcast node can determine the broadcast end time of the content data, the broadcast end instruction message may be configured not to be transmitted. However, in the configuration in which the broadcast end instruction message is transmitted, switching of the broadcast node is more efficient. Can be done well.

  As described above, according to the above embodiment, the broadcast time of the content data broadcast in the tree type broadcast system SX2, and the node indicating the content holding node storing the content data on the content distributed storage system SX1 Stores a broadcast list describing information and stores content data to be broadcast when the broadcast time arrives (for example, the broadcast time when the current content data is switched to the next content data arrives) By specifying a content holding node as a broadcast node from the broadcast list and transmitting a broadcast start instruction message indicating an instruction to broadcast the content data as a broadcast device in the tree-type broadcast system SX2 to the broadcast node. , Content retention node Since it is configured to broadcast content data to a certain broadcast node, it is possible to divide the broadcast node for each content data and eliminate the need to collectively have content data to be broadcast in a specific broadcast station. It is possible to reduce the load on a specific broadcasting station and the network load.

  Further, according to the above embodiment, the content holding node to be a broadcast node candidate can be quickly searched from the content distributed storage system SX1 according to DHT routing for each content data, and is effectively used in the tree type broadcast system SX2. can do.

  The content distributed storage system SX1 in the above embodiment has been described on the assumption that it is formed by an algorithm using DHT, but the present invention is not limited to this.

It is a figure which shows an example of the connection aspect of each node apparatus in the communication system which concerns on this embodiment. It is a conceptual diagram of the communication system S which concerns on this embodiment. It is a figure which shows an example of the routing table using DHT which node N2 hold | maintains. It is a conceptual diagram which shows an example of ID space of DHT. It is the conceptual diagram which showed an example of the flow of the content location inquiry (search) message sent from the user node in ID space of DHT. 2 is a diagram illustrating a schematic configuration example of a broadcast management server 10. FIG. It is a conceptual diagram which shows the content of a broadcast list. It is a figure which shows a mode when a broadcast node is switched. It is a figure which shows the example of an outline structure of the node Nn. (A) is a flowchart which shows the broadcast list production | generation process in the control part 101 of the broadcast management server 10, (B) is a flowchart which shows the band determination process in the control part 11 of a content holding node. 4 is a flowchart showing a connection destination introduction process in the control unit 101 of the broadcast management server 10. 4 is a flowchart showing a broadcast node switching process in the control unit 101 of the broadcast management server 10. It is the sequence figure which showed the exchange between the broadcast management server 10 and the node Nn at the time of broadcast node switching in time series.

Explanation of symbols

8 Network 9 Overlay Network 10 Broadcast Management Server 10a Broadcast Control Function
10b Introduction function 11 Control unit 12 Storage unit 13 Buffer memory 14 Decoder unit 15 Video processing unit 16 Display unit 17 Audio processing unit 18 Speaker 20 Communication unit 21 Input unit 22 Bus 101 Control unit 101 Storage unit 103 Communication unit 104 Bus Nn node S Communication system SX1 Distributed content storage system SX2 Tree-type broadcasting system

Claims (8)

Content distribution in which a plurality of content data is distributed and stored in a plurality of node devices, and each of the node devices provides content data stored by itself in response to a request from the other node device via a network A tree-type broadcast system including all or part of the plurality of node devices in a storage system and formed by participation of a plurality of node devices, wherein the plurality of node devices form a plurality of hierarchies with the broadcasting device as the highest level. In the tree-type broadcasting system, the content data broadcasted by the broadcasting device via the communication means is sequentially transferred from the node device in the upper layer to the node device in the lower layer. A broadcast management apparatus for managing broadcast of content data,
Storage means for storing a broadcast list in which the broadcast time of the content data and node information indicating a node device storing the content data on the content distributed storage system are described in association with each other;
Node specifying means for specifying, from the broadcast list, node information indicating the node device storing the content data to be broadcast when the broadcast time arrives;
Broadcast instruction information transmitting means for transmitting broadcast instruction information indicating an instruction to broadcast the content data as the broadcasting device in the tree-type broadcasting system to the node device indicated by the identified node information;
A broadcast management apparatus comprising: The broadcast management device according to claim 1,
In the broadcast list, broadcast time of a plurality of content data having different contents and node information indicating a node device storing each content data are described,
When the broadcast time at which the content data being broadcast is switched to the next content data has arrived, the node specifying means stores node information indicating the next node device storing the next content data. Identified from the broadcast list,
The broadcast instruction information transmitting means is broadcast instruction information indicating an instruction to cause the next node device indicated by the specified node information to broadcast the next content data as the broadcast device in the tree type broadcast system. The broadcast management apparatus characterized by transmitting. The broadcast management device according to claim 2,
When the broadcast time at which the content data being broadcast is switched to the next content data has arrived, the next node is connected to the lower layer node device connected to the node device as the broadcast device. A broadcast management apparatus, further comprising switching instruction information transmitting means for transmitting switching instruction information indicating an instruction to switch connection to the apparatus. In the broadcast management device according to any one of claims 1 to 3,
Search means for searching for a node device that stores the content data in which the broadcast time is described in the broadcast list in the content distributed storage system;
Among the searched node devices, a node device capable of consuming the bandwidth required as the broadcasting device is selected, and node information indicating the selected node device is associated with the broadcast time of the content data and the broadcasting is performed. Node selection description means described in the list,
The broadcast management apparatus further comprising: In the broadcast management device according to any one of claims 1 to 4,
When node information of a plurality of the node devices that store the content data in which the broadcast time is described in the broadcast list is described in the broadcast list, the node device of each of the node devices Connection time information acquisition means for acquiring connection time information indicating a connection time to the network from each of the node devices;
The node specifying unit compares the connection times indicated in the acquired connection time information, and specifies node information indicating one of the node devices based on the comparison result. apparatus.   A broadcast management processing program that causes the broadcast management apparatus according to any one of claims 1 to 5 to function. Content distribution in which a plurality of content data is distributed and stored in a plurality of node devices, and each of the node devices provides content data stored by itself in response to a request from the other node device via a network A tree-type broadcast system including all or part of the plurality of node devices in a storage system and formed by participation of a plurality of node devices, wherein the plurality of node devices form a plurality of hierarchies with the broadcasting device as the highest level. In the tree-type broadcasting system connected in a tree shape through the communication means, the content data broadcast by the broadcasting device is sequentially transferred from the node device in the upper layer to the node device in the lower layer.
A broadcast management apparatus that manages the broadcast of the content data,
Storage means for storing a broadcast list in which the broadcast time of the content data and node information indicating a node device storing the content data on the content distributed storage system are described in association with each other;
Node specifying means for specifying, from the broadcast list, node information indicating the node device storing the content data to be broadcast when the broadcast time arrives;
Broadcast instruction information transmitting means for transmitting broadcast instruction information indicating an instruction to broadcast the content data as the broadcasting device in the tree-type broadcasting system to the node device indicated by the identified node information;
With
The node device that has received the broadcast instruction information,
A tree-type broadcast system comprising broadcast means for broadcasting the content data stored by itself according to the received broadcast instruction information to a lower-layer node device connected to the content data. Content distribution in which a plurality of content data is distributed and stored in a plurality of node devices, and each of the node devices provides content data stored by itself in response to a request from the other node device via a network A tree-type broadcast system including all or part of the plurality of node devices in a storage system and formed by participation of a plurality of node devices, wherein the plurality of node devices form a plurality of hierarchies with the broadcasting device as the highest level. However, content in a tree-type broadcasting system that is connected in a tree shape via a communication means and that has been broadcasted by the broadcasting device is sequentially transferred from the node device in the upper layer to the node device in the lower layer. A broadcasting method,
A broadcast management device for managing the broadcast of the content data,
A broadcast list in which the broadcast time of the content data and node information indicating a node device storing the content data on the content distributed storage system are described in association with each other;
Node information indicating the node device storing the content data to be broadcast when the broadcast time arrives is identified from the broadcast list;
Broadcast instruction information indicating an instruction to broadcast the content data as the broadcasting device in the tree-type broadcasting system is transmitted to the node device indicated by the identified node information,
The node device is
Receiving the broadcast instruction information;
A content broadcasting method, comprising: broadcasting the content data stored by itself according to the received broadcast instruction information to a lower layer node device connected to the content data.

Images