JP5494361B2 - Distributed storage system, representative node device, notification method, and program - Google Patents

Description

  The present invention relates to a peer-to-peer (P2P) type communication system including a plurality of node devices that can communicate with each other via a network. Specifically, the present invention relates to a method for acquiring content from a content holder on a communication path with a small communication load.

  This type of peer-to-peer communication system includes a plurality of node devices. Content data of various contents is distributed and stored in a plurality of node devices as duplicate data (hereinafter referred to as “replica”) of the plurality of content data. The content data is content data such as movies and music. In general, a distributed storage system is known in which a replica can be used between node devices. This improves fault tolerance and access dispersibility. The location of replicas thus distributed and stored can be efficiently searched using a distributed hash table (hereinafter referred to as DHT (Distributed Hash Table)) as disclosed in Patent Document 1, for example.

  When the above-mentioned node device acquires desired content, a message (query) for searching for the location of the replica of the content data is transmitted to the other node devices. As a result, the message is transferred to the node device that manages the content data replica in accordance with the DHT. Then, the node device that has transmitted the message acquires information indicating the location of the replica from the management source node device. As a result, the node device that has transmitted the message can access the node device that stores the replica of the content data related to the search. A replica can be acquired (downloaded). In order to select a communication path with a small communication load, for example, Patent Document 2 discloses a technique in which an AS (Autonomous System) number to which a content holder belongs is used. The AS number is a number for identifying a network operated by a plurality of organizations in the Internet. Some also use the number of hops to select a route.

JP 2006-197400 A JP 2006-277338 A

  However, routers do not always respond when trying to measure the number of hops. Further, even if an AS number is used to determine a communication path, the AS number is not always assigned to all managers. Therefore, conventionally, a hint server (tracker) storing Internet topology information has been used to determine the communication load between all node devices. However, if the hint server is accessed every time content is acquired, the processing load on the hint server is concentrated and the processing load on the hint server is large.

  The present invention has been made to solve the above-described problems. An object of the present invention is to provide a communication method capable of reducing the processing load on the hint server.

According to the first aspect of the present invention, a plurality of primary device groups that provide a communication function by providing one or more relay devices that relay information transmitted / received on a network, and subordinate to the primary device group A plurality of secondary devices that are located and provide a communication function by providing one or more of the relay devices, and a plurality of secondary devices that are connected to the primary device group or the secondary device group A distributed storage system that distributes and stores a plurality of contents using an overlay network configured by node devices, wherein the distributed storage system includes the plurality of node devices and the primary node among the plurality of node devices. a representative node device respectively representatively connected to the device group and the second device group, information for storing a connection relationship between the primary device group and the second device group in the network The representative node device is a holding node that holds desired content among the plurality of node devices, and indicates the location of the representative node device on the network in the holding node Based on the first reception unit that receives a message including location information from any of the plurality of node devices, and the message received by the first reception unit, the location information included in the message indicates The first acquisition unit that acquires the primary device group to which the representative node device is connected or the secondary device group is acquired from the information processing device, and the first acquisition unit that acquires the first connection information. The storage unit for storing the first connection information, the first connection information acquired by the first acquisition unit, and the message received by the first reception unit. A transmission unit for transmitting to the source node device sage is a source, a distributed storage system comprising: a.

According to the first aspect of the present invention, the representative node device is configured such that the first connection information of the representative node device indicated by the location information included in the message received by the first reception unit is the storage unit. A determination unit that determines whether or not the first connection information is stored by the determination unit, the transmission unit stores the first stored in the storage unit 1 connection information is transmitted to the transmission source node device, and when the determination unit does not determine that the first connection information is stored, the first acquisition unit transmits the first connection information to the information The storage unit stores the first connection information acquired from the processing device and acquired by the first acquisition unit.

According to the invention described in claim 2 , the plurality of node devices acquire the location information of the representative node device of the primary device group or the secondary device group to which the plurality of node devices are connected, The node device includes: a search unit that searches for the location information of one or more holding node devices that hold desired content from the plurality of node devices; and a search result of the search unit as a search result of the holding node. Based on the location information of the representative node device in the holding node received by the second receiving unit and the second receiving unit that receives the location information of the representative node device of the content holding node together with the location information And a second acquisition unit that acquires the first connection information of the representative node device in the holding node from the representative node.

According to a third aspect of the present invention, the plurality of node devices acquire second connection information indicating the primary device group or the secondary device group to which the plurality of node devices are connected, and the node A device is connected to the node device searched by the search unit on the network based on the first connection information and the second connection information of the representative node device in the holding node acquired by the second acquisition unit. And a content acquisition unit that acquires the predetermined content from the content holding node at a short distance.

According to the fourth aspect of the present invention, a plurality of primary device groups that provide a communication function by providing one or more relay devices that relay information transmitted / received on a network, and subordinate to the primary device group A plurality of secondary devices that are located and provide a communication function by providing one or more of the relay devices, and a plurality of secondary devices that are connected to the primary device group or the secondary device group In a distributed storage system that distributes and stores a plurality of contents by an overlay network composed of node devices, a connection is made on behalf of the primary device group and the secondary device group among the plurality of node devices. The representative node device is a holding node that holds desired content among the plurality of node devices, and the representative node device is the representative node device that holds the desired content. Based on the message received from any one of the plurality of node devices and the message received by the first receiver, a message including location information indicating the location of the node device on the network, The primary device group to which the representative node device indicated by the location information included in the message is connected, or the first connection information indicating the secondary device group, is used as the primary device group and the secondary device in the network. Acquired by the first acquisition unit acquired from the information processing apparatus that stores the connection relationship with the device group, the storage unit that stores the first connection information acquired by the first acquisition unit, and the first acquisition unit A transmission unit that transmits the first connection information to a transmission source node device that is a transmission source of the message that has received the message by the first reception unit. It is a representative node device.

According to the invention of claim 4 , the representative node device is configured such that the first connection information of the representative node device indicated by the location information included in the message received by the first receiving unit is the storage unit. A determination unit that determines whether or not the first connection information is stored by the determination unit, the transmission unit stores the first stored in the storage unit 1 connection information is transmitted to the transmission source node device, and when the determination unit does not determine that the first connection information is stored, the first acquisition unit transmits the first connection information to the information The storage unit stores the first connection information acquired from the processing device and acquired by the first acquisition unit.

According to the fifth aspect of the present invention, a plurality of primary device groups that provide a communication function by providing one or more relay devices that relay information transmitted / received on a network, and subordinate to the primary device group A plurality of secondary devices that are located and provide a communication function by providing one or more of the relay devices, and a plurality of secondary devices that are connected to the primary device group or the secondary device group In a distributed storage system that distributes and stores a plurality of contents by an overlay network composed of node devices, a connection is made on behalf of the primary device group and the secondary device group among the plurality of node devices. The representative node device is a holding node that holds desired content among the plurality of node devices, and is in front of the representative node device in the holding node. A first reception step of receiving a message including location information indicating a location on a network from any of the plurality of node devices, and the message includes the message based on the message received by the first reception step. The primary device group to which the representative node device indicated by the location information is connected, or the first connection information indicating the secondary device group is connected to the primary device group and the secondary device group in the network. A first acquisition step acquired from the information processing apparatus storing the relationship; a storage step of storing the first connection information acquired in the first acquisition step in a storage unit; and the first acquisition step acquired in the first acquisition step. 1 connection information, sent to a sender of the message received message by the first receiving step the transmission source node apparatus Is a program for causing execute a transmission step, the to. According to the fifth aspect of the present invention, the first connection information of the representative node device indicated by the location information included in the message received by the first reception step is transmitted to the computer of the representative node device. A determination step for determining whether or not the information is stored in the storage unit is executed, and when the determination step determines that the first connection information is stored, the transmission step is stored in the storage unit. The first connection information is transmitted to the transmission source node device, and when the determination step determines that the first connection information is not stored, the first acquisition step includes the first connection information. Is acquired from the information processing apparatus, and the storage step stores the first connection information acquired in the first acquisition step in the storage unit. And characterized by causing the computer to perform.

According to the sixth aspect of the present invention, a plurality of primary device groups that provide a communication function by providing one or more relay devices that relay information transmitted and received on the network, and a lower level of the primary device group A plurality of secondary devices that are located and provide a communication function by providing one or more of the relay devices, and a plurality of secondary devices that are connected to the primary device group or the secondary device group A distributed storage system that distributes and stores a plurality of contents by an overlay network configured by node devices, and among the plurality of node devices included in the distributed storage system, the primary device group and the secondary device A communication method of a representative node device connected on behalf of a group, the holding node holding desired content among the plurality of node devices, wherein the holding node A first reception step of receiving from one of the plurality of node devices a message including location information indicating the location of the representative node device on the network, and based on the message received by the first reception step. The primary device group to which the representative node device in the holding node indicated by the location information included in the message is connected or the first connection information indicating the secondary device group is obtained as the primary connection in the network. A first acquisition step of acquiring from the information processing apparatus storing the connection relationship between the device group and the secondary device group; and a storage step of storing the first connection information acquired in the first acquisition step in a storage unit; The first connection information acquired by the first acquisition step is sent to the message by the first reception step. A transmission step of transmitting to a transmission source of the received message source node apparatus, a communication method, which comprises a. Further, the communication method determines whether or not the first connection information of the representative node device indicated by the location information included in the message received by the first reception step is stored in the storage unit And when the determination step determines that the first connection information is stored, the transmission step transmits the first connection information stored in the storage unit to the transmission source node device. And when the determination step does not determine that the first connection information is stored, the first acquisition step acquires the first connection information from the information processing apparatus, and the storage step The storage device stores the first connection information acquired in the first acquisition step.

  According to the first aspect of the present invention, the representative node device is based on the message received by the first receiving unit, the primary device group to which the representative node device indicated by the location information included in the message is connected, or A first acquisition unit that acquires first connection information indicating a secondary device group from the information processing apparatus is provided. Further, the representative node device includes a storage unit that stores the first connection information acquired by the first acquisition unit. Moreover, the transmission part which transmits the 1st connection information acquired by the 1st acquisition part to the transmission source node apparatus which is a transmission source of the message which received the message by the 1st reception part is provided. Therefore, on behalf of a plurality of node devices, the representative node device can acquire and store the first connection information in the information processing device. As a result, the processing load on the information processing apparatus functioning as the hint server can be prevented from being concentrated, and the processing load on the hint server can be reduced.

According to the first aspect of the present invention, the representative node device determines whether or not the first connection information of the representative node device indicated by the location information included in the message received by the first receiving unit is stored in the storage unit. A determination unit for determining When the determination unit determines that the first connection information is stored, the transmission unit transmits the first connection information stored in the storage unit to the transmission source node device. When the determination unit does not determine that the first connection information is stored, the first acquisition unit acquires the first connection information from the information processing apparatus, and the storage unit is the first acquisition unit. The first connection information acquired by is stored. Therefore, when the representative node device stores the first connection information, the information processing device does not need to be accessed. As a result, the representative node device can save at least a part of the first connection information stored in the information processing device functioning as a hint server. Therefore, it is possible to prevent the processing load on the information processing apparatus functioning as the hint server from being concentrated, and to reduce the processing load of the hint server.

According to the second aspect of the present invention, the node device includes the second receiving unit that receives the location information of the representative node device of the holding node as well as the location information of the holding node as a search result by the search unit. The node device includes a second acquisition unit that acquires the first connection information of the holding node from the representative node based on the location information of the representative node device of the holding node received by the second receiving unit. Therefore, in order to determine the content acquisition destination, the node device that searches for the content can acquire the first connection information from the representative node device. As a result, the node device can acquire the first connection information in order to determine the content acquisition destination, and the processing load on the information processing device functioning as the hint server is prevented from being concentrated, thereby reducing the processing load on the hint server. Can be made.

According to the invention described in claim 3 , the node device is searched by the search unit based on the first connection information and the second connection information of the content holding node acquired by the second acquisition unit. And a content acquisition unit that acquires predetermined content from a holding node having a short distance on the network. As a result, the content can be acquired from the node device that acquires the content and the holding node that is close in distance on the network.

According to the invention of claim 4 , the representative node device is based on the message received by the first receiving unit, the primary device group to which the representative node device indicated by the location information included in the message is connected, or A first acquisition unit is provided that acquires first connection information indicating a secondary device group from an information processing apparatus that stores a connection relationship between the primary device group and the secondary device group in the network. Further, the representative node device includes a storage unit that stores the first connection information acquired by the first acquisition unit. Moreover, the transmission part which transmits the 1st connection information acquired by the 1st acquisition part to the transmission source node apparatus which is a transmission source of the message which received the message by the 1st reception part is provided. Therefore, on behalf of a plurality of node devices, the representative node device can acquire and store the first connection information in the information processing device. As a result, the processing load on the information processing apparatus functioning as the hint server can be prevented from being concentrated, and the processing load on the hint server can be reduced.

According to the invention of claim 4 , the representative node device determines whether or not the first connection information of the holding node indicated by the location information included in the message received by the first receiving unit is stored in the storage unit. A determination unit for determining is provided. When the determination unit determines that the first connection information is stored, the transmission unit transmits the first connection information stored in the storage unit to the transmission source node device. When the determination unit does not determine that the first connection information is stored, the first acquisition unit acquires the first connection information from the information processing apparatus, and the storage unit is the first acquisition unit. The first connection information acquired by is stored. Therefore, when the representative node device stores the first connection information, the information processing device does not need to be accessed. As a result, the representative node device can save at least a part of the first connection information stored in the information processing device functioning as a hint server. Therefore, it is possible to prevent the processing load on the information processing apparatus functioning as the hint server from being concentrated, and to reduce the processing load of the hint server.

According to the fifth aspect of the present invention, the primary device group or the secondary device group to which the representative node device indicated by the location information included in the message is connected based on the message received in the first receiving step. The 1st acquisition step which acquires the 1st connection information shown from the information processing apparatus which memorize | stored the connection relation of the primary apparatus group and secondary apparatus group in a network is performed. In addition, the computer of the representative node device executes a storage step of storing the first connection information acquired in the first acquisition step in the storage unit. Moreover, the transmission step which transmits the 1st connection information acquired by the 1st acquisition step to the transmission source node apparatus which is the transmission source of the message which received the message by the 1st reception step is performed. Therefore, on behalf of a plurality of node devices, the representative node device can acquire and store the first connection information in the information processing device. As a result, the processing load on the information processing apparatus functioning as the hint server can be prevented from being concentrated, and the processing load on the hint server can be reduced.

According to the sixth aspect of the present invention, based on the message received in the first receiving step, the primary device group to which the representative node device in the holding node indicated by the location information included in the message is connected, or the secondary device A first acquisition step of acquiring the first connection information indicating the device group from the information processing apparatus storing the connection relationship between the primary device group and the secondary device group in the network is executed. Further, the representative node device executes a storage step of storing the first connection information acquired in the first acquisition step in the storage unit. Moreover, the transmission step which transmits the 1st connection information acquired by the 1st acquisition step to the transmission source node apparatus which is the transmission source of the message which received the message by the 1st reception step is performed. Therefore, on behalf of a plurality of node devices, the representative node device can acquire and store the first connection information in the information processing device. As a result, the processing load on the information processing apparatus functioning as the hint server can be prevented from being concentrated, and the processing load on the hint server can be reduced.

It is a figure which shows an example of the connection mode of each node apparatus Nn in the distributed storage system S of this embodiment. It is explanatory drawing which shows the specific example of network structures, such as the general internet. 3 is a conceptual diagram of topology information stored in a hint server 10. FIG. FIG. 10 is an explanatory diagram for explaining an operation outline of the distributed storage system S. It is a block diagram which shows the electric constitution of the node apparatus Nn of this embodiment. It is a flowchart which shows the procedure of the main process operation | movement of operation | movement in the node apparatus Nn. It is a flowchart which performs the representative node process of the node apparatus Nn according to a representative node process program. It is a block diagram which shows the electric constitution of a private hint server. It is a flowchart which shows a private hint server main operation | movement process.

(First embodiment)
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best embodiment of the invention will be described with reference to the drawings.

[Configuration of distributed storage system]
FIG. 1 shows a distributed storage system S of the present embodiment. The distributed storage system S includes a plurality of node devices Nn (n = 1, 2, 3,...).

  As shown in FIG. 1, the node devices Nn are connected to each other via a network NW. The node devices N1, N2, and N3 in FIG. 1 are directly connected to the network NW without using a broadband router. On the other hand, the node devices N4, N5, N6, and N7 are connected to the network NW via the broadband router BR. General network NWs such as the Internet include IX (Internet eXchange), ISP (Internet Service Provider), DSL (Digital Subscriber Line) line provider equipment, FTTH (Fiber To The Home) line provider equipment, communication line It is constructed by etc. For example, the communication line is a telephone line or an optical cable. Note that a router for transferring data (packets) is appropriately inserted in the network NW, but the illustration is omitted.

  Each node device Nn is assigned a unique manufacturing number and an IP (Internet Protocol) address. The distributed storage system S of this embodiment is a peer-to-peer network system. Note that the peer-to-peer network system of the present embodiment is realized by the overlay network OL. The overlay network OL is constructed by virtually linking the plurality of node devices Nn in FIG. In other words, the overlay network OL is a logical network. The overlay network OL is constructed by a specific algorithm. For example, the overlay network OL is constructed by an algorithm using DHT described in Japanese Patent Application Laid-Open No. 2006-197400.

  A node ID is assigned to each node device Nn constituting the overlay network OL. The node ID is unique identification information consisting of a predetermined number of digits. More specifically, the node ID is generated based on the IP address or manufacturing number individually assigned to each node device Nn. The node ID is a value obtained by hashing the above-described IP address or manufacturing number with a common hash function. For example, a hash value having a bit length of 160 bits is generated by a hash function such as SHA-1. Each node ID is distributed in a certain ID space without any deviation. The peer-to-peer network system is formed by participation of any one of the node devices Nn among these node devices Nn. Participation in the present embodiment means that the node device Nn connects to the distributed storage system S and transmits / receives content data.

  In participation in the distributed storage system S, a node device Nn not currently participating in the overlay network OL transmits a participation message indicating a participation request to any node device Nn currently participating. The node device that receives the participation message is a node device that always participates in the distributed storage system S. In this embodiment, a node device that always participates is called a contact node. For example, a participation message is transmitted from a node device not participating in the overlay network OL to the contact node of the distributed storage system S. The contact node transmits information necessary for participating in the overlay network OL to the node device that is the transmission source of the participation message. Details of the necessary information will be described later.

  Although not shown in FIG. 1, the distributed storage system S includes a content input server. The distributed storage system S includes a hint server 10. The content input server is a server for inputting new content data into the distributed storage system S. The content input server inputs a replica obtained by copying content data to the distributed storage system S.

  The hint server 10 shown in FIG. 2 stores topology information of the upper device group and the lower device group connected to the Internet. Details of the topology information stored in the hint server will be described later. Instead of constructing the hint server 10, a contact node described later may be constructed with the function of the hint server 10. The hint server 10 of this embodiment is an example of an information processing apparatus of the present invention.

  FIG. 2 shows a specific example of a network structure such as a general Internet. IX (Internet eXchange) 3 connects a plurality of device groups via a network. The upper device groups 13a to 13c are connected via IX with IX3 as the apex. Lower device groups 14a and 14b are connected to the lower level of the upper device group 13a with IX3 as the apex. In the example of FIG. 2, the lower device groups 14a and 14b are connected only to the upper device group 13a. However, the lower device group may be connected to the upper device group 13b or the upper device group 13c. The upper device groups 13a to 13c and the lower device groups 14a and 14b are composed of a plurality of broadband routers BR. The broadband router BR constituting each device group is managed by an arbitrary administrator. Each broadband router BR is assigned a predetermined range of IP addresses. IP addresses corresponding to a plurality of broadband routers BR constituting the upper device groups 13a to 13c are set as the IP address range of the upper device groups 13a to 13c. Similarly, the IP addresses of a plurality of broadband routers BR constituting the lower device groups 14a and 14b are set as the IP address range of the lower device groups 14a and 14b.

  The upper device group or the lower device group described in the present embodiment is, for example, an ISP (Internet Service Provider). Each ISP connected to the Internet in the real world is connected according to the above-described relationship between the upper level and the lower level. The host device group of this embodiment is, for example, a primary ISP. In addition, the lower device group of the present embodiment is, for example, a secondary ISP. The primary ISP and the secondary ISP are connected by the above-described relationship between the upper level and the lower level. The primary ISP is connected to a higher rank than the secondary ISP.

  As shown in FIG. 2, a large number of node devices Nn are connected via the broadband router BR to the lower device groups 13a to 13c or the lower device groups 14a and 14b with IX3 as a vertex. Further, the node device Nn is connected to the broadband router BR via the station building modem 15. The broadband router BR and the node device Nn may be directly connected.

  Furthermore, in this embodiment, a representative node device is installed in each of the above-described upper device group or lower device group. The representative node device is a node device that represents each upper device group or lower device group. The representative node device connected to each upper device group or lower device group is determined from among the node devices connected to each upper device group or lower device group. The method for determining the representative node device may be determined by an arbitrary method. The representative node device connected to each upper device group or lower device group stores the network distance between the representative node devices. Details of the network distance determination method will be described later.

  As a modification of the present embodiment, the private hint server shown in FIG. 2 may be installed in each of the upper device group and the lower device group. At least one private hint server 11 is installed in each upper device group or each lower device group. Each private hint server stores at least topology information of an upper device group or a lower device group to which the private hint server is connected. In the example shown in FIG. 2, private hint servers 11a, 11b, 11c, 11d, and 11e are connected to each upper device group or lower device group. Details of the topology information will be described later. The private hint server of the present invention is an example of an information processing apparatus of the present invention.

[Description of content acquisition operation of distributed storage system]
Each node device Nn shown in FIG. 1 or FIG. 2 holds a routing table using DHT. This routing table defines various message transfer destinations on the distributed storage system S. Specifically, a plurality of pieces of node information including the node ID, IP address, and port number of the node device Nn that are moderately separated in the ID space are registered in this routing table. In the present embodiment, the node information includes “node ID”, “IP address and port number”, and “IP address of the representative node device” of the message transmission destination candidate. The IP address of the representative node device is the IP address of the representative node of the upper device group or the lower device group to which the node device represented by the node ID included in the node information is connected.

  One node connected to the distributed storage system S stores the minimum necessary node information of the node Nn as a routing table. By transferring various messages between the nodes Nn, node information about the node Nn that does not store node information is acquired. In the present embodiment, when various messages are transmitted or transferred to the above-described other node device Nn using the routing table, the message transmission source or the node information of the node device Nn of the transfer source is included and transmitted. The Each node device Nn that has received this message registers and updates the received node information in the routing table and index cache held by each node device Nn. With such a configuration, each node device Nn can grasp node information of other node devices. 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.

  In the distributed storage system S, various content data replicas having different contents are distributed and stored in a plurality of node devices Nn in a predetermined file format. The content is a movie and a movie, or music. A replica can be transmitted and received between the node devices Nn.

  Each of these content data replicas is given information including a content name (title) and a content ID. The content name may be a title of content data. The content ID is content identification information unique to each content. For example, the content ID is generated by hashing the content name + arbitrary numerical value with a hash function common to that for obtaining the node ID. For this reason, the content ID is arranged in the same ID space as the node ID. Alternatively, the system administrator may assign a unique ID value for each content data. The ID value may have the same bit length as the node ID. A content catalog list describing the correspondence between content names and their content IDs is distributed to all nodes Nn. In the content catalog list, the content name, the content ID, and the publication start date and time and the publication end date and time of the replica represented by the content ID are described in association with each other. Details of the content catalog list are described in Japanese Patent Application Laid-Open No. 2008-129694, and detailed description thereof is omitted.

  As described above, the location of replicas distributed and stored is managed by index information. The index information is composed of information obtained by combining the information of the node device Nn in which the replica is stored and the content ID of the replica. The index information is stored by the node device Nn that manages the location of the replica. A node device that manages the location of a replica is referred to as a “root node”. That is, the node information of the node device Nn that stores the replica of the content data is managed by the root node so that it can be provided in response to an inquiry from another node device Nn. The node device Nn that stores the content replica is assumed to be a “holding node”. As such a root node, a node Nn having a node ID closest to the content ID is selected. For example, “closest to the content ID” means that the upper digits match more or the difference between the comparison results is the smallest.

  The root node receives a publish message from the holding node. Then, the root node registers the content ID and node information included in the publish message in the index cache as index information. The node information includes “node ID”, “IP address and port number”, and “IP address of representative node device”. The IP address of the representative node device is the IP address of the representative node of the upper device group or the lower device group to which the node device represented by the node ID included in the node information is connected.

  When a user of a certain node device wants to acquire a replica of desired content data, the user who wants to acquire the replica generates a query. A node device Nn that the user desires to acquire a replica is referred to as a “user node”. The query includes the content ID of the content data and the IP address of the user node. The content ID included in the query is the content ID of the content data selected from the content catalog list by the user.

  The user node transmits a query to another node device Nn according to the routing table of the user node. That is, the user node transmits the query toward the root node. Thus, the query arrives at the root node using the content ID as a key.

  The root node that has received the query acquires index information corresponding to the content ID included in the query from the index cache storage area. The acquired index information is returned to the user node that is the transmission source of the query. Thus, the user node that acquired the index information can know the IP address of the holding node from the acquired index information. Based on the acquired IP address of the holding node, the user node transmits a content transmission request message. The user node can obtain (download) a replica of the content data from the holding node. When acquiring a replica, the content ID of the replica is acquired together with the replica.

  The user node stores a replica of the content data acquired from the holding node in a storage unit such as a hard disk. The user node storing the replica informs the root node that the replica has been stored. In order to notify that the replica has been saved, the user node generates a publish message including the content ID of the replica and the node information of the user node. The generated publish message is transmitted from the user node to the root node. By transmitting the publish message, the other node devices Nn participating in the distributed storage system S can acquire (download) the replica from the user node that acquired the replica.

  By the above-described method, the publish message arrives at the root node by DHT routing using the content ID as a key, like the query. Then, the root node can register index information including the node information of the user node included in the received publish message and the set of the content ID of the replica. Thus, the user node becomes a new holding node that holds a replica of the content. Note that the index information of the user node included in the publish message is also registered in the node device Nn in the transfer path up to the root node. The root node may transmit the content transmission request message to the holding node indicated by the IP address or the like included in the location information. In this case, the holding node accesses the user node and provides the content.

  All contents stored in the distributed storage system S are managed by the content management server. In the present embodiment, the content management server is not shown. The content management server stores attribute information of all contents stored in the distributed storage system S. Then, the content management server MS distributes content catalog information including content attribute information to all the node devices Nn by DHT multicast. In DHT multicast, messages distributed from a content management server to a certain node Nn are sequentially transferred to the node devices Nn connected to the distributed storage system S according to a routing table using DHT. As a result, all node devices Nn are finally distributed. The DHT multicast is known in, for example, Japanese Patent Application Laid-Open No. 2007-053662, and detailed description thereof is omitted.

[Description of topology information]
FIG. 3 is a conceptual diagram of topology information stored in the hint server 10. The topology information represents a connection mode with the upper device group and the lower device group. Specifically, the topology information is composed of connection relation information and IP address range information. The connection relationship information is information that represents the connection relationship between a plurality of upper device groups or lower device groups that constitute the Internet. The IP address range information is an IP address range corresponding to each of the upper device group and the lower device group. For example, the connection relation information is information indicating that the upper device group connected to the upper device group 13a in FIG. 3 is the upper device groups 13b and 13c. Further, the information indicates that the lower device groups connected to the upper device group 13a are the lower device groups 14a and 14b.

  When the user node acquires the content, the content can be acquired from the holding node device that is the smallest route between the device groups based on the topology information and the IP address of the user node. In the present embodiment, the user node represents a node device Nn that generates a query in accordance with an instruction from the user. The holding node represents a node device Nn in which content data is stored. In the present embodiment, in addition to the participation process for participating in the overlay network OL, an upper device group or a lower device group to which the node device Nn is connected is determined. Specifically, based on the IP address included in the participation message transmitted by the node device Nn, a higher device group or a lower device group to which the node device Nn that transmitted the participation message is connected is determined.

  A method for determination will be specifically described. Specifically, the above-described IP address range information is an address range “10.10.10.10 to 10.10.10.90”. This address range indicates an address assigned to the broadband router BR included in the upper device group or the lower device group. Hereinafter, a case where the contact node has the function of the hint server 10 will be described. When a certain node device participates in the overlay network OL, the participating node device transmits a participation message to the contact node. The contact node is a device that is first accessed by a node device participating in the overlay network OL. Details of the contact node will be described later. The participating node device Nn transmits a participation message toward the contact node. The participation message includes the IP address of the node device that transmits the participation message. For example, when the IP address of the node device N13 is “10.10.10.89”, the participation message includes the IP address “10.10.10.89”. Then, a higher-level device group or a lower-level device group including the IP address “10.10.10.89” included in the participation message as an address range is determined by the contact node. For example, since the IP address “10.10.10.89” is included in the address range “10.10.10.10.10.10.10.90” described above, the address range “10.10.10. An upper device group or a lower device group corresponding to “10 to 10.10.10.90” is determined.

  In the present embodiment, it is assumed that the contact node knows the address range corresponding to each upper device group or lower device group. The determined upper device group or lower device group is transmitted from the contact node to the participating node device. By executing this process, the participating node device can acquire the upper device group or the lower device group to which the participating node device is connected. By executing the same processing as described above for the holding node, the holding node can acquire the upper device group or the lower device group to which the holding node is connected. Details of the holding node will be described later. Unlike the contact node, when the hint server 10 is established, a node device participating in the overlay network OL or a holding node accesses the hint server 10. In this case, when the participating node device transmits a participation message to the contact node, the participating node device can acquire the IP address of the hint server 10 from the contact node. Then, by executing the processing described above, the participating node device or the holding node can acquire the upper device group or the lower device group to which the node device is connected.

  Furthermore, in the present embodiment, the hint server 10 stores the IP address of the representative node device of the upper node device group or lower device group to which the participating node device or holding node is connected. The hint server 10 determines the participating node device or the upper device group or the lower device group to which the holding node is connected. Then, the representative node device of the determined upper device group or lower device group is determined. The determined IP address of the representative node device is transmitted from the hint server 10 to the participating node device or holding node. Thereby, the participating node device or the holding node can access the representative node device.

  In the modification of the present embodiment, when each of the upper device group and the lower device group includes a private hint server, the private hint server is in the upper device group or the lower device group to which the private hint server is connected. The topology information is stored. In this case, the node device connected in each device group, the number of routers passing from the node device to the private hint server, and the like may be stored as topology information. The upper device group of this embodiment is an example of the primary device group of the present invention. The lower device group of the present embodiment is an example of the secondary device group of the present invention.

[Operation overview of distributed storage system S]
The operation outline of the distributed storage system S of the present embodiment will be described with reference to FIG. Hereinafter, a case where the contact node has the function of the hint server 10 will be described. A case where the node device N13 illustrated in FIG. 4 participates in the overlay network OL will be described as an example. The node device N13 participating in the overlay network OL first transmits a participation message to the contact node. The participation message includes the IP address of the node device N13. The contact node that has received the participation message determines a higher-level device group or a lower-level device group to which the node device N13 is connected based on the IP address of the node device N13. Then, the representative node device of the determined upper device group or lower device group is determined. The determined IP address of the representative node device is transmitted to the node device N13.

  Then, the node device N13 generates a query for searching for predetermined content as a user node. The generated query is transmitted toward the root node by the node device N13. Then, the node device N13 acquires an index cache.

  The node device N13 that has acquired the index cache determines whether the network distance between the representative node device of the node device described in the index cache and the representative node device of the user node is stored in the storage unit of the node device N13. . When the network distance is stored in the storage unit of the node device N13, the network distance stored in the storage unit is referred to. On the other hand, if not stored in the storage means of the node device N13, a request message is transmitted from the node device N13 to the representative node device of the device group to which the node device N13 is connected (arrow (1) in FIG. 4). In the example of FIG. 4, the node device N13 is connected to the lower device group 14a. Therefore, a request message is transmitted to the representative node device N24 of the lower device group 14a. The request message to be transmitted includes the IP address of the representative node of the user node and the IP address of the holding node whose network distance is to be determined.

  The representative node device N24 that has received the request message determines whether the network distance between the representative node device of the holding node included in the request message and the representative node device N24 is stored in the storage unit of the representative node device N24. If it is stored in the storage means of the representative node device N24, the network distance stored in the storage means is transmitted to the node device N13 (arrow (2) in FIG. 4). On the other hand, if not stored in the storage means of the representative node device N24, the representative node device N24 transfers the request message to the hint server 10 (arrow (3) in FIG. 4). The hint server 10 receives the request message transmitted from the representative node device N24. The hint server 10 determines the network distance between the representative node device of the holding node and the representative node device of the user node included in the received request message. The network distance determined by the hint server 10 is transmitted to the representative node device N24 (arrow (4) in FIG. 4). The representative node device N24 stores the received network distance in the storage unit of the representative node device N24. Thus, even if the representative node device N24 is inquired again about the network distance between the representative node device of the holding node and the representative node device N24, the representative node device N24 refers to the network distance stored in the storage unit of the representative node device N24. be able to.

  The representative node device N24 that has received the network distance from the hint server 10 transfers the received network distance to the user node (arrow (5) in FIG. 4). The user node that has received the network distance stores the received network distance in the storage means of the user node. In this way, the representative node devices connected to each higher-level device group or lower-level device group store the network distance, so that access concentration to the hint server 10 can be distributed.

(How to determine network distance)
A network distance determination method used in the present embodiment will be described. In the present embodiment, the network distance is determined based on the number of upper device groups or lower device groups that pass from the user node to the holding node.

  Specifically, description will be made using an example in which the node device N13 which is a user node illustrated in FIG. 3 transmits a query to the root node. As an example, the node device N13 stores the node information of the node device N11, the node device N15, the node device N16, the node device N19, and the node device N20 as content holding nodes in the root node. Then, the root node transmits the index cache to the node device N13 as a content acquisition candidate destination. The node device N13 that has received the acquisition candidate destination determines a holding node as a content acquisition destination based on the network distance.

The network distance of the present embodiment is determined according to the following rules.
1. When the representative node device of the user node and the representative node device of the holding node are connected to the same lower device group, the network distance is set to zero.
2. The representative node device of the user node and the representative node device of the holding node are not connected to the same lower device group, and the representative node device of the user node and the representative node device of the holding node are connected to the same upper device group. In this case, the network distance is 1.
3. The representative node device of the user node and the representative node device of the holding node are not connected to the same lower device group, and the representative node device of the user node and the representative node device of the holding node are connected to the same upper device group. Furthermore, when the representative node of the holding node is directly connected to another higher level device group different from the higher level device group to which the representative node device of the user node is connected, the network distance is set to 2.
4). The representative node device of the user node and the representative node device of the holding node are not connected to the same lower device group, and the representative node device of the user node and the representative node device of the holding node are connected to the same upper device group. Furthermore, the other upper device group different from the upper device group to which the representative node device of the user node is connected and the representative node device of the user node are not directly connected, but are connected to the lower device group of the other upper device group. Network distance is 3.

  In the present embodiment, content data is acquired from a holding node with a short network distance based on the above rules. Therefore, the communication load between the device groups can be reduced by reducing the number of device groups that pass through when acquiring content.

  An example will be described in which the node device N13 stores node information of the node device N11, the node device N15, the node device N16, the node device N19, and the node device N20 as the holding node in the root node. In this case, since the node device N13 and the node device N15 are connected to the same lower device group 14a, the network distance becomes zero. Further, since the node device N13 and the node device N16 are connected to the same higher-level device group 13a, the network distance is 1. Further, since the node device N13 and the node device N11 are connected to the same higher-level device group 13a, the network distance is 1. Further, the node device N13 and the node device N19 are connected to different higher-level device groups, and the node device N19 is directly connected to the higher-level device group 13b, so that the network distance is 2. Further, the node device N13 and the node device N20 are not connected to the same lower device group, are not connected to the upper device group, and are different from the upper device group 13a to which the node device N13 is connected. It is not directly connected to the device group 13b, but is connected to the lower device group 14c of the other higher device group 13b. Therefore, the network distance is 3.

  In the present embodiment, the process for determining the content acquisition destination is performed by the user node. By transmitting the IP address of the representative node device of the user node together with the query, the user node can determine the content acquisition destination by the root node. In this case, the content acquisition destination determined by the root node is transmitted to the user node. In addition, the content transmission request message may be transmitted to the holding node determined as the acquisition destination. The network distance may be determined by the hint server 10.

  In the present embodiment, the number of device groups that are routed is the network distance, but is not limited to this. The number of routers and hubs that pass through may be used as the network distance. Further, a transit fee generated when passing through the upper device group or the lower device group may be used as the network distance.

[Electric configuration of node equipment]
Next, the electrical configuration of the node device Nn will be described with reference to FIG. FIG. 5 is a block diagram showing an electrical configuration of the node device Nn of this embodiment. As shown in FIG. 5, the node device Nn according to the present embodiment includes a CPU 1 that controls the node device Nn. An HDD 2, a RAM 3, a decoder unit 4, and a communication unit 9 are electrically connected to the CPU 1. The storage means such as the HDD 2 and the RAM 3 and the CPU 1 constitute a computer of the node device Nn. The computer controls the operation of the node device Nn.

  The HDD 2 includes a program storage area 21. The program storage area 21 includes a main operation program storage area 22 and a representative node processing program storage area 23. The main operation program storage area 22 stores program information for controlling the node device Nn. The representative node processing program storage area 23 is a program for controlling the node device Nn as a representative node of the present embodiment.

  The RAM 3 includes a representative node information temporary storage area 31, a distance information temporary storage area 32, and a holding node information temporary storage area 33. The representative node information temporary storage area 31 temporarily stores the IP address of the representative node of the upper device group or the lower device group to which the node device Nn including the RAM 3 is connected. The distance information temporary storage area 32 temporarily stores the network distance between the representative node of the node device Nn including the RAM 3 and the representative node of the holding node. Specifically, the distance information temporary storage area 32 temporarily stores the network distance received by the node device Nn including the RAM 3. The holding node information temporary storage area 33 temporarily stores the network distance between the node device including the RAM 3 and the representative node of the holding node included in the acquired index cache. Specifically, the network distance between the representative node device of each holding node described in the index cache acquired when the node device Nn acquires the content and the representative node device of the user node device that acquires the content is temporarily Remembered. The representative node information temporary storage area 31, the distance information temporary storage area 32, and the holding node information temporary storage area 33 may be provided in the HDD 2, respectively. The distance information temporary storage area 32 of the present embodiment is an example of a storage unit of the present invention.

  The decoder unit 4 decodes video information and audio information. Decoding in this embodiment is data expansion or decoding of encoded video information and audio information. Video information and audio information are included in the content data.

  The video processing unit 5 performs a predetermined drawing process on the decoded video information and outputs a video signal.

  The display 6 displays a video based on the video signal output from the video processing unit 5. The display 6 is configured by a CRT display or a liquid crystal display.

  The audio processing unit 7 performs D (Digital) / A (Analog) conversion of the decoded audio information into an analog audio signal.

  The speaker 8 amplifies the changed analog audio signal by an amplifier and outputs it.

  The communication unit 9 connects the node device Nn to the Internet. The communication unit 9 transmits / receives information to / from another node device Nn, content input server, hint server 10 or private hint server via the network NW.

  As the node device Nn, a personal computer, an STB (Set Top Box), a TV receiver, or the like is applicable.

  When the distributed storage system S includes a contact node that is an access destination when participating in the distributed storage system S, the contact node's IP address or port number is stored in the HDD 2 of each node device Nn. Yes. Further, the HDD 2 stores a content catalog list. The program stored in the HDD 2 may be downloaded from a predetermined server on the network NW, for example. Further, the program may be recorded on a recording medium such as a CD-ROM and read via a drive of the recording medium.

[Main processing operation of node device Nn]
The operation and action of the node device Nn of the present embodiment having the above-described configuration will be described with reference to the accompanying drawings. FIG. 6 is a flowchart showing a procedure of the main processing operation of the operation in the node device Nn. In other words, FIG. 6 is a flowchart showing the processing procedure of the operation in the user node. When the node device Nn makes a request for the above-described participation process to the overlay network OL, the main operation of the node device Nn is executed. When the CPU 1 executes the main operation program, the main operation process is performed. The processing shown below is processed by the CPU 1.

  In step S101, a participation process is executed. When the participation process is executed, the IP address of the representative node apparatus of the node apparatus that executes the participation process is acquired from the contact node. The acquired IP address of the representative node device is temporarily stored in the representative node information temporary storage area 31.

  In step S102, it is determined whether or not the node device Nn is turned off. When it is determined that the power is turned off, the main operation process is terminated. If it is not determined that the power has been turned off, step S103 is executed.

  In step S103, it is determined whether or not a download request has been made. As a download request, a request for downloading a predetermined content is input from the user of the node device Nn. If it is determined that there is a download request, step S104 is executed. If it is not determined that there has been a download request, step S102 is executed.

In step S104, the node device Nn searches for a holding node. In particular,
A query is generated by the node device Nn. An index cache is obtained based on the generated query. In the acquired index cache, node information of a holding node that holds predetermined content is registered. The acquired index cache is temporarily stored in a predetermined storage area of the RAM. The computer of this embodiment and step S104 are an example of the search part of this invention, a 2nd receiving part, and a 2nd acquisition part.

  In step S105, it is determined whether the network distances of all the holding node devices among the holding node devices included in the index cache have been acquired. The holding node from which the network distance has been acquired is identified by a flag or the like. When it is determined that the network distances of all holding nodes have been acquired, step S113 is executed. If it is not determined that the network distances of all holding nodes have been acquired, step S106 is executed.

  In step S106, one holding node for which the network distance has not been acquired is selected. A holding node whose network distance has not been acquired is identified by a flag or the like.

  In step S107, the IP address of the representative node device of the holding node selected in step S106 is acquired. The IP address of the representative node device is included in the node information of the holding node in the index information acquired in step S104. The acquired IP address of the representative node device of the holding node is temporarily stored in a predetermined storage area of the RAM 3.

  In step S108, whether or not the distance information stored in the distance information temporary storage area 32 includes the network distance between the representative node device of the holding node acquired in step S107 and the representative node device of the node device Nn. Is determined. If it is determined that the network distance is registered, step S109 is executed. If the network distance is not registered, step S110 is executed. The IP address of the representative node device of the node device Nn is temporarily stored in the representative node information temporary storage area 31.

  In step S109, the network distance determined to exist in step S108 is acquired from the distance information temporary storage area 32 and temporarily stored in the holding node information temporary storage area 33.

  In step S110, a network distance between the representative node device of the holding node selected in step S106 and the representative node device of the node device Nn is requested to the representative node device of the node device Nn. Specifically, a request message including the IP address of the representative node device of the holding node whose network distance is to be determined and the IP address of the node device Nn that is the message transmission source is sent to the representative node device of the node device Nn. Sent.

  In step S111, the network distance requested in step S110 is received.

  In step S112, the network distance received in step S111 is temporarily stored in the holding node information temporary storage area 33. Further, the network distance received in step S111 is temporarily stored in the distance information temporary storage area 32.

  In step S113, the holding nodes are sorted in the order of the shortest network distances temporarily stored in the holding node information temporary storage area 33. The sorted result is temporarily stored in the holding node information temporary storage area 33 again.

  In step S114, the contents are downloaded with priority from the order of the shortest network distances sorted in step S113. For example, a download request is transmitted toward the holding node in the order of short network distance. A download request is transmitted to the holding node at a predetermined time interval from the order of short network distance. When there are a plurality of holding nodes having the same network distance, the download may be performed with priority from the holding nodes whose responses are returned quickly among the plurality of holding nodes. The computer of this embodiment and step S114 are an example of the content acquisition part of this invention.

[Representative node processing]
FIG. 7 is a flowchart for executing representative node processing of the node device Nn according to the representative node processing program. The representative node processing is executed in parallel with the main operation processing of the node device Nn shown in FIG. 6 when the power of the representative node device is turned on. First, in step S201, it is determined whether the power of the representative node device has been turned off. If it is determined that the power of the representative node device has been turned off, the representative node process is terminated. If it is not determined that the power of the representative node device is turned off, step S202 is executed.

  In step S202, it is determined whether a network distance request message has been received. The request message received in step S202 is the request message transmitted by the node device Nn in step S110 of FIG. When it is determined that the request message has been received, step S203 is executed. When it is not determined that the request message has been received, step S201 is executed again. The computer of this embodiment and step S202 are an example of the 1st receiving part of this invention. Further, step S202 of the present embodiment is an example of a first reception step of the present invention.

  In step S203, it is determined whether or not the requested network distance is stored in the distance information temporary storage area 32 of the representative node device. It is determined whether the representative node IP address of the holding node included in the request message received in step S202 and the network distance between the representative node device that has received the request message are stored. If it is determined that the requested network distance is stored, step S204 is executed. If it is not determined that the requested network distance is stored, step S205 is executed. The computer of this embodiment and step S203 are an example of the determination unit of the present invention.

  In step S204, the network distance temporarily stored in the distance information temporary storage area 32 of the representative node device that has received the request message is acquired.

  In step S <b> 205, the request message is transferred to the hint server 10.

  In step S206, the network distance requested by the request message transferred in step S205 is received by the representative node device. The computer of this embodiment and step S206 are an example of the 1st acquisition part of this invention. Moreover, step S206 of this embodiment is an example of a first acquisition step of the present invention.

  In step S207, the network distance received in step S206 is temporarily stored in the distance information temporary storage area 32. Step S207ha of the present invention is an example of the storage step of the present invention.

  In step 208, the network distance acquired in step S204 or the network distance received in step S206 is transmitted to the node device Nn that requested the network distance in step S202. The computer of this embodiment and step S208 are an example of the transmission part of this invention. Moreover, step S208 of this embodiment is an example of the transmission step of this invention.

In the present embodiment, instead of the hint server 10, the representative node connected to each upper device group or lower device group can store the network distance. As a result, it is possible to prevent network distance requests from being concentrated on the hint server 10.

  In the present embodiment, each representative node device is configured to be able to store the received network distance. The representative node device may store the topology information of this embodiment instead of storing the network distance. In this case, the topology information stored in the representative node device is necessary topology information because the network distance is determined by the user node or the representative node device. As a result, the topology information stored in the hint server 10 can be distributed and stored in the representative node device, so that load concentration on the hint server 10 can be prevented.

(Modification)
Hereinafter, modifications of the present embodiment will be described. In the modification, a private hint server is provided in each of the upper device group and the lower device group. Therefore, the private hint server stores topology information of the upper device group or the lower device group to which the private hint server is connected. In this case, in step S205 shown in FIG. 7, the network distance is requested to the higher level device group connected to the representative node device that executes the representative node process shown in FIG. 7 or the private hint server connected to the lower level device group. The

  Hereinafter, the electrical configuration of the private hint server will be described with reference to FIG. FIG. 8 is a block diagram showing an electrical configuration of the private hint server. As shown in FIG. 8, the private hint server includes a CPU 20 that controls the private hint server. The CPU 20 is electrically connected to the HDD 17, the RAM 18, and the communication unit 19. The storage means such as the HDD 17 and the RAM 18 and the CPU 20 constitute a computer of a private hint server. The computer controls the operation of the private hint server. The hint server 10 has the same electrical configuration as that of the private hint server.

  The HDD 17 includes a program storage area 171. The program storage area 171 includes a private hint server main operation program storage area 172. The private hint server main operation program storage area 172 stores program information for controlling the private hint server. The program stored in the HDD 17 may be downloaded from a predetermined server on the network NW, for example. Further, the program may be recorded on a recording medium such as a CD-ROM and read via a drive of the recording medium.

  Hereinafter, the operation processing of the private hint server that has received the network distance request from the representative node device will be described with reference to FIG.

  FIG. 9 is a flowchart showing the private hint server main operation process. When the private hint server is powered on, the private hint server main operation process is executed.

  First, in step S301, it is determined whether or not the private hint server is turned off. When it is determined that the private hint server is powered off, the private hint server main operation process is terminated. If it is not determined that the private hint server is powered off, step S302 is executed.

  In step S302, it is determined whether a request message transmitted or transferred from the representative node device has been received. The request message received in step S302 is the request message transmitted by the node device Nn in step S110 of FIG. When it is determined that the request message has been received, step S303 is executed. If it is not determined that the request message has been received, step S301 is executed again. Note that a request message transmitted or transferred from a private hint server connected to a lower device group may be received in step S302.

  In step S303, it is determined whether or not the IP address of the representative node device of the holding node received in step S302 is an IP address within the assigned range of the private hint server. In the modification, a private hint server is provided in each of the upper device group and the lower device group. Therefore, the private hint server stores topology information of the upper device group or the lower device group to which the private hint server is connected. In step S303, whether or not the IP address of the representative node device of the holding node included in the request message is included in the IP address range of the upper device group or lower device group to which the private hint server that has received the request message is connected. Is determined. When it is determined that the IP address of the representative node device in the holding node is within the assigned range, step S304 is executed. When it is not determined that the IP address of the representative node device is within the assigned range, step S305 is executed.

  In step S304, the network distance between the representative node device of the holding node and the representative node device of the user node is determined based on the topology information stored in the private hint server. The determined network distance is temporarily stored in a predetermined storage area of the RAM 18.

  In step S305, it is determined whether a higher-level device group exists in the private hint server that has received the request message in step S302. If the private hint server that received the request message in step S302 connects to the lower device group, it is determined that the upper device group exists. If the private hint server that received the request message in step S302 connects to a device other than the lower device group, it is determined that there is no higher device group. If it is determined that a higher device group exists, step S306 is executed. If it is determined that the upper device group does not exist, step S307 is executed.

  In step S306, the request message is transferred to the private hint server of the higher-level device group.

  In step S307, the request message is transferred to the hint server 10.

  In step S308, the network distance is received from the private hint server or the hint server 10 of the upper device group that transferred the request message in step S306. The received network distance is the network distance requested in step S306 or step S307. The received network distance is temporarily stored in a predetermined storage area of the RAM 18.

  In step S309, the network distance determined in step S304 or the network distance received in step S308 is transmitted to the representative node device that requested the network distance in step S302 or a private hint server connected to the lower-level device group. Is done.

  In the modification, a private hint server is installed for each upper device group or lower device group, and topology information stored by the hint server 10 is distributed and stored. As a result, since the private hint server is installed in each upper device group or lower device group, it is possible to prevent the topology information of each device group from being disclosed to the outside as much as possible. Access load can be distributed to private hint servers.

  Moreover, in the said embodiment, although the peer to peer network using DHT was applied to overlay network OL, it is not restricted to this. A routing table using DHT may be used. For example, a system using another overlay network may be applied. As a peer-to-peer system that does not use DHT, for example, there is a hybrid peer-to-peer system.

1 CPU
2 HDD
3 RAM
4 Decoder unit 5 Video processing unit 6 Display 7 Audio processing unit 8 Speaker 9 Communication unit 10 Hint server 11a, 11b, 11c, 11d, 11e Private hint server 13a, 13b, 13c Upper device group 14a, 14b Lower device group 15 Station Modem 16 CPU
17 HDD
18 RAM
DESCRIPTION OF SYMBOLS 19 Communication part 21 Program storage area 22 Main processing operation program storage area 23 Representative node processing program storage area 31 Representative node information temporary storage area 32 Distance information temporary storage area 33 Holding node information temporary storage area
171 Program storage area 172 Hint server main operation processing program storage area S Distributed storage system X IX
NW network OL overlay network BR broadband router Nn node equipment

Claims (6)

A plurality of primary device groups that provide a communication function by providing one or more relay devices that relay information transmitted and received on the network;
A plurality of secondary device groups that are located under the primary device group and provide a communication function by including one or more relay devices;
A distributed storage system that distributes and stores a plurality of contents by an overlay network configured by a plurality of node devices connected to the primary device group or the secondary device group in a network configured by:
The distributed storage system includes:
The plurality of node devices;
Among the plurality of node devices, a representative node device respectively representatively connected to the primary device group and the second device group,
An information processing apparatus storing a connection relationship between the primary device group and the secondary device group in the network;
With
The representative node device is:
Among the plurality of node devices, a message that is a holding node that holds desired content and includes location information indicating the location of the representative node device on the network in the holding node is sent to the plurality of node devices. A first receiving unit for receiving from any one of the following:
Based on the message received by the first reception unit, the primary device group or the secondary device group to which the representative node device indicated by the location information included in the message is connected is connected. A first acquisition unit for acquiring connection information from the information processing apparatus;
A storage unit for storing the first connection information acquired by the first acquisition unit;
A transmission unit that transmits the first connection information acquired by the first acquisition unit to a transmission source node device that is a transmission source of the message that has received the message by the first reception unit;
A determination unit that determines whether or not the first connection information of the representative node device indicated by the location information included in the message received by the first reception unit is stored in the storage unit;
When the determination unit determines that the first connection information is stored, the transmission unit transmits the first connection information stored in the storage unit to the transmission source node device,
When the determination unit does not determine that the first connection information is stored, the first acquisition unit acquires the first connection information from the information processing apparatus, and the storage unit A distributed storage system , wherein the first connection information acquired by the first acquisition unit is stored . The plurality of node devices acquire the location information of the representative node device of the primary device group or the secondary device group to which the plurality of node devices are connected,
The node device is
A search unit that searches the location information of one or more holding node devices holding desired content from the plurality of node devices;
A second reception unit that receives the location information of the representative node device of the content holding node together with the location information of the holding node as a search result by the search unit;
A second acquisition unit that acquires, from the representative node, the first connection information of the representative node device in the holding node based on the location information of the representative node device in the holding node received by the second receiving unit. When,
The distributed storage system according to claim 1, further comprising: The plurality of node devices acquire second connection information indicating the primary device group or the secondary device group to which the plurality of node devices are connected,
The node device is
Based on the first connection information of the representative node device in the holding node acquired by the second acquisition unit and the second connection information, the distance between the node device searched by the search unit and the network is determined. A content acquisition unit for acquiring the predetermined content from the nearby content holding node;
The distributed storage system according to claim 2 , further comprising: A plurality of primary device groups that provide a communication function by providing one or more relay devices that relay information transmitted and received on the network;
A plurality of secondary device groups that are located under the primary device group and provide a communication function by including one or more relay devices;
In a distributed storage system that distributes and stores a plurality of contents by an overlay network configured by a plurality of node devices connected to the primary device group or the secondary device group in a network configured by: among the plurality of node devices, a representative node device respectively representatively connected to the primary device group and the second device group,
The representative node device is:
Among the plurality of node devices, a message that is a holding node that holds desired content and includes location information indicating the location of the representative node device on the network in the holding node is sent to the plurality of node devices. A first receiving unit for receiving from any one of the following:
Based on the message received by the first receiver, the first connection group indicating the primary device group or the secondary device group to which the representative node device indicated by the location information included in the message is connected A first acquisition unit that acquires information from an information processing apparatus that stores a connection relationship between the primary device group and the secondary device group in the network;
A storage unit for storing the first connection information acquired by the first acquisition unit;
A transmission unit that transmits the first connection information acquired by the first acquisition unit to a transmission source node device that is a transmission source of the message that has received the message by the first reception unit;
A determination unit that determines whether or not the first connection information of the representative node device indicated by the location information included in the message received by the first reception unit is stored in the storage unit;
When the determination unit determines that the first connection information is stored, the transmission unit transmits the first connection information stored in the storage unit to the transmission source node device,
When the determination unit does not determine that the first connection information is stored, the first acquisition unit acquires the first connection information from the information processing apparatus, and the storage unit The representative node device stores the first connection information acquired by the first acquisition unit . A plurality of primary device groups that provide a communication function by providing one or more relay devices that relay information transmitted and received on the network;
A plurality of secondary device groups that are located under the primary device group and provide a communication function by including one or more relay devices;
In a distributed storage system that distributes and stores a plurality of contents by an overlay network configured by a plurality of node devices connected to the primary device group or the secondary device group in a network configured by: Among a plurality of node devices, a computer of a representative node device connected as a representative to the primary device group and the secondary device group,
Among the plurality of node devices, a message that is a holding node that holds desired content and includes location information indicating the location of the representative node device on the network in the holding node is sent to the plurality of node devices. A first receiving step for receiving from either of them;
Based on the message received in the first reception step, the primary device group or the secondary device group to which the representative node device indicated by the location information included in the message is connected is connected. A first acquisition step of acquiring information from an information processing apparatus storing a connection relationship between the primary device group and the secondary device group in the network;
A storage step of storing the first connection information acquired in the first acquisition step in a storage unit;
A transmission step of transmitting the first connection information acquired in the first acquisition step to a transmission source node device that is a transmission source of the message that has received the message in the first reception step;
A determination step of determining whether or not the first connection information of the representative node device indicated by the location information included in the message received by the first reception step is stored in the storage unit; ,
When it is determined by the determination step that the first connection information is stored, the transmission step transmits the first connection information stored in the storage unit to the transmission source node device,
When the determination step does not determine that the first connection information is stored, the first acquisition step acquires the first connection information from the information processing apparatus, and the storage step includes Storing the first connection information acquired in the first acquisition step in the storage unit;
That causes the computer to execute the program. A plurality of primary device groups that provide a communication function by providing one or more relay devices that relay information transmitted and received on the network;
A plurality of secondary device groups that are located under the primary device group and provide a communication function by including one or more relay devices;
A distributed storage system that distributes and stores a plurality of contents by an overlay network configured by a plurality of node devices connected to the primary device group or the secondary device group in a network configured by: among the plurality of node devices distributed storage system comprises a communication method of the representative node device respectively representatively connected to the primary device group and the second device group,
Among the plurality of node devices, a message that is a holding node that holds desired content and includes location information indicating the location of the representative node device on the network in the holding node is sent to the plurality of node devices. A first receiving step for receiving from either of them;
Based on the message received in the first receiving step, the primary device group or the secondary device group to which the representative node device in the holding node indicated by the location information included in the message is connected A first acquisition step of acquiring, from an information processing apparatus that stores a connection relationship between the primary device group and the secondary device group in the network;
A storage step of storing the first connection information acquired in the first acquisition step in a storage unit;
A transmission step of transmitting the first connection information acquired in the first acquisition step to a transmission source node device that is a transmission source of the message that has received the message in the first reception step;
A determination step of determining whether or not the first connection information of the representative node device indicated by the location information included in the message received by the first reception step is stored in the storage unit,
When it is determined by the determination step that the first connection information is stored, the transmission step transmits the first connection information stored in the storage unit to the transmission source node device,
When the determination step does not determine that the first connection information is stored, the first acquisition step acquires the first connection information from the information processing apparatus, and the storage step includes The communication method , wherein the first connection information acquired in the first acquisition step is stored in the storage unit .

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