JP2010039722A - Node device, management node device, node processing program, management node processing program, content distribution storage system, and replica data acquisition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a node device or the like reducing concentration of a load on a communication route on a WAN (Wide Area Network) side, to improve operation efficiency of a system by preferentially acquiring a replica of content from another node device connected to a LAN (Local Area Network) when the node device connected to the LAN acquires the replica of the content. <P>SOLUTION: The node device is included in a content distributed storage system having a plurality of LANs connected to a plurality of node devices, having a network wherein the LANs are connected to each other through communication means, storing a plurality of replica data of the content in a distributed manner, and transferring the replica data between the respective node devices. The node device has: a means for detecting the node device storing the replica data of the content to be acquired in the LAN connected to the device; a means for detecting the node device connected to another LAN, storing the replica data when no corresponding node device is detected; and a means for requesting the node device to acquire the replica data. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  In this type of peer-to-peer communication system, copy data (hereinafter referred to as “replica”) of a plurality of content data (content data such as movies and music) is distributed and stored (arranged) in a plurality of node devices. A distributed content storage system that makes it possible to use replicas between node devices is known, and this improves fault tolerance and access dispersibility. The location of the replicas thus distributed and stored can be efficiently searched using a distributed hash table (hereinafter referred to as DHT (Distributed Hash Table)) as disclosed in, for example, Patent Document 1.

When a node device participating in such a distributed content storage system desires to acquire a replica of a certain content, a desired content replica is stored among other node devices participating in the system. The replica is obtained by accessing the node device that is currently operating.
JP 2006-197400 A

  In order to exchange information with an external network (WAN: Wide Area Network), a hotel or a karaoke shop where one internet line connected to the external network is drawn in the building is assumed.

  When a plurality of node devices respectively installed in each room in such a building participate in the content distributed distribution system and communication such as acquisition of a content replica is performed simultaneously using the system, an external network There is a risk of overloading the Internet line. In particular, when the capacity of replicas such as audio data and moving image data is large, there is a concern that an excessive load is applied to the Internet line.

  The present invention has been made in view of the above problems, and when a node device connected to a local area network obtains a replica of content, the node device is prioritized from other node devices connected to the local area network. It is an object of the present invention to provide a node device or the like that reduces the concentration of a load on the communication path on the WAN side and improves the operation efficiency of the system.

  In order to solve the above problem, the invention according to claim 1 includes a plurality of local area networks to which a plurality of node devices are connected, and the plurality of local area networks are connected to each other via communication means. A node device included in a distributed content storage system including a network, in which duplicate data of a plurality of contents is distributed and stored in the plurality of node devices, and the copy data can be exchanged between the node devices. To check whether there is another node device that stores the copy data of the content to be acquired and that is connected to the local area network to which the node device is connected. If there is one existence check means and the other node device, the other node device storing the duplicated data Second existence confirmation means for confirming whether or not there is another node device connected to another local area network different from the local area network to which the self is connected, and the existence is confirmed A copy data acquisition means for requesting the copy data to another node device that has been made and acquiring the copy data;

  According to the present invention, when the node device connected to the local area network acquires the copy data of the content, it is preferentially acquired from the other node devices connected to the local area network, so that the WAN side It is possible to reduce the concentration of the load on the communication path of the system and improve the operation efficiency of the system.

  According to a second aspect of the present invention, in the node device according to the first aspect, the first presence check means is only for other node devices connected to the local area network to which the first presence confirmation unit is connected. The duplicated data is saved by transmitting a confirmation message that is distributed and receiving a save / not-answer response message indicating whether or not the duplicate data of the content returned from the other node device that has received the confirmation message is saved. It is characterized by confirming whether another node apparatus exists.

  According to the present invention, the other node devices connected to the local area network confirm whether or not the copy data of the desired content is stored and receive a storage presence / absence response message indicating whether or not the copy data is stored. Thus, it is possible to reliably confirm the existence of another node device storing the duplicated data.

  A third aspect of the present invention is the node apparatus according to the first aspect, wherein the node apparatus is another node apparatus that participates in the distributed content storage system as a node apparatus that can exchange the duplicated data, and is connected to itself. It further comprises node list storage means for storing a node list in which information of other node devices connected to the local area network is described, and the first existence confirmation means has information described in the node list By transmitting a confirmation message that is distributed only to other node devices, and receiving a storage presence / absence response message indicating whether or not the copy data of the content returned from the other node device that received the confirmation message is stored, It is characterized in that it is confirmed whether or not there is another node device storing the duplicated data.

  According to the present invention, the node device is another node device connected to the local area network to which the node device is connected, and the node device participates in the content distribution storage system with a desired content. It is possible to efficiently check whether duplicate data is stored.

  According to a fourth aspect of the present invention, in the node device according to the third aspect, a confirmation message is transmitted periodically only to other node devices connected to the local area network to which the node device is connected. Based on the participation confirmation means for receiving a participation presence / absence response message indicating whether or not to participate in the distributed content storage system returned from the other node device that has received the confirmation message, and the received participation presence / absence response message And node list updating means for updating the node list.

  According to this invention, the node device confirms whether or not it regularly participates in the distributed content storage system with respect to other node devices connected to the local area network to which it is connected, By updating the node list, the node list can be kept up-to-date.

  According to the fifth aspect of the present invention, information on node devices participating in the distributed content storage system as node devices that can exchange the duplicated data among node devices connected to the local area network is provided to the local area network. And a management node device that centrally manages the information indicating whether or not the copy data of the content is stored in the node device, and the first existence confirmation unit is connected to the local area network to which the node device is connected. Node information indicating information of a node device that stores a copy of the content sent back from the management node device that has transmitted the confirmation message to the management node device connected to the management node device and has received the confirmation message Save the duplicate data by receiving the response message A node device according to claim 1, characterized in that the other node devices that confirms whether there exists.

  According to the present invention, a node device stores copy data of desired content from a management node device that centrally manages information indicating whether or not copy data is stored in a node device connected to a local area network to which the node device is connected. Since the device information can be received, the presence of another node device in the local area network storing the replicated data can be reliably confirmed only by exchanging with the management node device.

  A sixth aspect of the present invention is a management node apparatus that receives the confirmation message from the node apparatus according to the fifth aspect, and is a node apparatus that is connected to a local area network to which the node apparatus is connected. A node that stores a node list in which information on node devices that participate in the distributed content storage system as node devices that can exchange the duplicated data, and information that indicates whether or not the duplicate data of the content in the node devices is saved Periodically send a confirmation message to only the list storage means and other node devices connected to the local area network to which it is connected, and reply from the other node device that received the confirmation message The storage presence / absence response message indicating whether or not the copied data of the content thus stored is stored is received. A content existence confirmation means for, based on the received stored whether the response message, characterized in that it comprises a node list updating means for updating the node list.

  According to the present invention, the management node device periodically checks whether or not the replicated data is stored in other node devices connected to the local area network to which the management node device is connected, and updates the node list. As a result, the node list can be kept up-to-date.

  The invention according to claim 7 is a management node device that receives the confirmation message from the node device according to claim 5, and is a node device connected to a local area network to which the node device is connected. A node that stores a node list in which information on node devices that participate in the distributed content storage system as node devices that can exchange the duplicated data, and information that indicates whether or not the duplicate data of the content in the node devices is saved A list storage means and a storage presence / absence message indicating whether or not to store the duplicate data transmitted from the node device when the duplicate data is newly saved or deleted in the node device whose information is described in the node list A storage presence / absence message receiving means for receiving the received storage presence / absence message Zui it, characterized in that it comprises a node list updating means for updating the node list.

  According to the present invention, when there is a new storage or deletion of the replicated data stored in the node device, the management node device receives the storage presence / absence message indicating the storage presence / absence, thereby replicating in each node device. The node list can be updated by checking whether data is stored, and the node list can be kept up-to-date.

  The invention according to claim 8 is the node device according to claim 1, wherein content is distributed and stored as a node device that can exchange the duplicated data among node devices connected to a local area network to which the node device is connected. A node list storage means for storing a node list in which information of a node device participating in the system and information indicating whether or not the copy data of the content is stored in the node device is further included; The means is characterized by confirming whether or not there is another node device storing the duplicate data by referring to the node list.

  According to the present invention, the node device is another node device connected to the local area network to which the node device is connected, and stores the copy data of the content in the node device participating in the content distributed storage system. The presence or absence can be confirmed efficiently.

  The invention according to claim 9 is the node device according to claim 7, wherein the node device according to claim 7 periodically transmits a confirmation message to only other node devices connected to the local area network to which the node device is connected. Based on the content presence / absence confirmation means for receiving a storage presence / absence response message indicating whether or not the copy data of the content returned from the other node device that received the confirmation message is stored, and the received storage presence / absence response message And node list updating means for updating the node list.

  According to the present invention, the node device is another node device connected to the local area network to which the node device is connected, and is replicated data stored in the node device participating in the distributed content storage system. When there is a new save or delete of the node, by receiving a save presence / absence message indicating whether or not the save is performed, the node list is updated by confirming whether or not the copy data is saved in each node device. Can be kept in a state.

  The invention described in claim 10 is transmitted from the node device according to claim 7 when the duplicate data is newly stored or deleted in the node device whose information is described in the node list. A storage presence / absence message receiving unit that receives a storage presence / absence message indicating whether the copied data is stored; and a node list update unit that updates the node list based on the received storage presence / absence message. It is characterized by.

  According to the present invention, it is possible to prevent duplicate data of content data from being distributed and stored in an excessive number of node devices.

The invention according to claim 11 is a node processing program that causes a computer to function as the node device according to any one of claims 1 to 5 and 8 to 10.
A twelfth aspect of the invention is a management node processing program that causes a computer to function as the management node device according to the sixth or seventh aspect.

  The invention according to claim 13 includes a network having a plurality of local area networks to which a plurality of node devices are connected, the plurality of local area networks being connected to each other via communication means, In a distributed content storage system in which replicated data is distributed and stored in the plurality of node devices, and the replicated data can be exchanged between the node devices, one of the node devices stores the replicated data of the content to be acquired First existence confirmation means for confirming whether there is another node device connected to the local area network to which the other node device is connected, and the other node If the device does not exist, it is another node device that stores the duplicate data and the node to which it is connected. A second existence confirmation unit for confirming whether or not there is another node device connected to another local area network different from the local area network; Copy data acquisition means for requesting and acquiring the copy data.

  The invention described in claim 14 includes a network having a plurality of local area networks to which a plurality of node devices are connected, the plurality of local area networks being connected to each other via communication means, A copy data acquisition method in a distributed content storage system in which copy data is distributed and stored in the plurality of node devices, and the copy data can be exchanged between the node devices, wherein the one node device acquires A step of confirming whether there is another node device that stores duplicate data of the content to be processed and that is connected to the local area network to which it is connected; If there is no other node device, it is another node device that stores the duplicated data and is connected by itself. A step of confirming whether there is another node device connected to another local area network different from the existing local area network, and the duplicate data for the other node device whose existence has been confirmed. Requesting and acquiring this.

  According to the present invention, when the node device connected to the local area network acquires the copy data of the content, the local area area is obtained by preferentially acquiring from other node devices connected to the local area network. It is possible to reduce the load concentration on the communication path on the WAN side outside the network, and to improve the operation efficiency of the system.

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

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

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

  As shown in the lower frame 101 of FIG. 1, IX (Internet eXchange) 3, ISP (Internet Service Provider) 4, DSL (Digital Subscriber Line) line operator (device) 5, FTTH (Fiber To The Home) line The company (device) 6, routers 7 a and 7 b, switching hub 8, communication line (for example, telephone line, optical cable, etc.) 10, etc. can be used for WAN (Wide Area Network) or LAN (Local Area Network). A network (real world network) 50 is constructed.

  In such a network 50, a router 7 for transferring data (packets) by a plurality of node devices (hereinafter referred to as “nodes”) Nn (n = 1, 2, 3,...). Or via a switching hub 8 or the like. Each node Nn is assigned a unique manufacturing number and an IP (Internet Protocol) address. The content distributed storage system S according to the present embodiment is a peer-to-peer network system formed by participation of any of a plurality of nodes Nn, as shown in the upper frame 100 of FIG. It has become.

  The network 12 shown in the upper frame 100 of FIG. 1 is an overlay network 60 (logical network) that configures a virtual link formed using the existing network 50. Such an overlay network 60 is realized by a specific algorithm, for example, an algorithm using DHT.

  Each node N1 to N18 participating in the overlay network 60 is assigned a node ID that is unique identification information having a predetermined number of digits. The node ID is, for example, a value (for example, the bit length is 160 bits) obtained by hashing an IP address or a manufacturing number individually assigned to each node Nn with a common hash function (for example, SHA-1). Yes, it will be distributed in one ID space without any bias. In the figure, nodes N1 to N18 are nodes participating in the overlay network 60, and nodes N21 to N28 are nodes not participating in the overlay network 60.

  Participation in the overlay network 60 means that a non-participating node Nn (for example, the node N21) is a participating node Nn (for example, a contact node that is always participating in the overlay network 60 (for example, the node N1) )) By sending a participation message indicating a participation request.

  Each of the nodes N1 to N18 participating in the overlay network 60 holds a routing table using DHT. This routing table defines the transfer destinations of various messages on the overlay network 60. Specifically, node information including the node ID, IP address, and port number of the node Nn that is moderately separated in the ID space is stored. Multiple registered. The IP address and port number are examples of network address information.

  One node Nn participating in the overlay network 60 registers node information of the minimum necessary node Nn among all the nodes Nn participating in the overlay network 60 in the routing table. For the node Nn that does not know (store) information, various messages are transferred between the nodes Nn to be delivered.

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

  By the way, in the overlay network 60, for example, copy data of various contents having different contents such as movies and music (hereinafter referred to as “replicas”) are distributed and stored in a plurality of nodes N1 to N18 in a predetermined file format ( And the replica can be used between the nodes Nn. For example, the node N5 stores a replica of the movie content with the title XXX, while the node N3 stores a replica of the movie content with the title YYY. (Hereinafter referred to as “content storage node”).

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

  In addition, the location of the replica stored in this manner, that is, the index information including the set of the node information of the node Nn storing the replica and the content ID corresponding to the replica of the content is the replica of the content. Is stored (stored in the index cache) and managed by a node Nn (hereinafter referred to as “root node” or “root node of content data (content ID)”) that manages the location of

  That is, the node information of the content storage node that stores the content replica is managed by the root node so that it can be provided in response to an inquiry from another node Nn.

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

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

  The attribute information such as the content name and content ID of the content to be selected by the user in each of the nodes N1 to N18 is described in, for example, content catalog information distributed from the content providing server SA to all the nodes Nn. The content ID included in the content location inquiry message may be generated by the user node by hashing the content name with the common hash function. The DHT routing is known in Japanese Patent Application Laid-Open No. 2006-197400 and the like, and thus detailed description thereof is omitted.

  The root node that receives the content location inquiry message acquires index information corresponding to the content ID included in the content node from the index cache, and sends the index information to the user node that is the transmission source of the content location inquiry message. Reply. In this way, the user node that has acquired the index information connects to the content storage node based on the network address information of the content storage node included in the index information, transmits a content transmission request message, and from there the content replica It becomes possible to get. The index information may include, for example, node information of a plurality of content storage nodes (when replicas of the same content are stored in a plurality of content storage nodes). In such a case, the user node can select one content storage node from among the plurality of content storage nodes and connect to the selected content storage node to obtain a content replica.

  The root node transmits a content transmission request message to the content storage node indicated by the network address information included in the index information, and the user node acquires the replica from the content storage node. You can also The user node can also acquire the index information from a cache node that caches the same index information as the root node until the content location inquiry message reaches the root node.

  In addition, the user node that has stored the replica of the content acquired from the content storage node notifies the root node that the replica has been stored (in other words, to other nodes Nn participating in the overlay network 60). In order to make it public, a publish (registration notification) message including the content ID of the replica and its own node information is generated, and the publish message is sent to the root node (to the root node). .

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

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

  Here, it is assumed that there are a plurality of nodes Nn participating in (or not participating in) the overlay network 60 in the same area (for example, in the same building such as a hotel or a karaoke shop).

  For example, as shown in FIG. 1, seven nodes Nn are connected to the router 7a, and one LAN (la) is formed by the seven nodes Nn connected to the router 7a. The seven nodes Nn are connected to the WAN via the router 7a.

  Also, seven nodes Nn are connected to the router 7b, and a LAN (lb) is formed by these nodes Nn. In addition, seven nodes Nn are connected to the switching hub 8, and a LAN (lc) is formed by these nodes Nn.

  In addition, although it demonstrates using a router and a switching hub as an example of the relay apparatus which forms LAN here, it is not restricted to these routers and a switching hub, but the network address contained in the various messages from the connected node Nn, data, etc. It is possible to use a relay device that detects information and can transmit various messages, data, and the like only to an appropriate port (node Nn designated as a destination) according to network address information among the connected nodes Nn. .

  When a node Nn connected to a LAN via such a relay device acquires a content replica, first, a desired node Nn connected to the LAN to which the node Nn is connected is desired. Whether or not the content replica is stored is confirmed. When the replica is stored, the replica is acquired from the other node Nn in the LAN via the LAN. On the other hand, when the other node Nn in the LAN to which it is connected does not store a replica of the desired content, it is obtained from the other node Nn outside the LAN. In order to obtain a replica from another node Nn outside the LAN, first, according to the operation procedure in the overlay network 60 described above, first send a “content location inquiry message”, then obtain index information from the root node, Based on the network address information (IP address and port number) of a storage node included in the index information, a connection is made to the storage node, a content transmission request message is transmitted and requested, and a replica of the content is obtained therefrom. .

  Thus, when a node Nn obtains a content replica, it first checks whether there is a node that stores a replica of the desired content in another node Nn in the LAN to which the node Nn is connected. By preferentially obtaining replicas from the storage nodes, the concentration of load on the communication path on the WAN side is reduced. For example, in the case of LAN (la), the communication path on the WAN side is the communication line 10 or the like connected between the router 7a and the FTTH line operator (device) 6 and the LAN (lb). In the case of the communication line 10 or the like connected between the router 7b and the FTTH line carrier (device) 6, and in the case of LAN (lc), the switching hub 8 and the DSL line provider (device) 5 Communication line 10 connected between the two.

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

  FIG. 2 is a diagram illustrating a schematic configuration example of the node Nn. The nodes N1 to N18 participating in the overlay network 60 and the nodes N21 to N28 not participating in the overlay network 60 have the same configuration and function.

  As shown in FIG. 2, the node Nn includes a control unit 11 as a computer including a CPU having a calculation function, a working RAM, a ROM for storing various data and programs, and various data (for example, content data). When the replica and the node Nn are participating in the overlay network 60, the storage unit 12 includes an HD (hard disk) or the like for storing and storing (stores) index information, DHT, and the like)) and various programs. A buffer memory 13 for temporarily storing a replica of the received content data and the like, and decoding the encoded video data (video information) and audio data (audio information) included in the content data replica (data expansion and decoding) And the like, and the decoded part 14 A video processing unit 15 that performs predetermined rendering processing on video data and outputs the video signal; a display unit 16 such as a CRT or a liquid crystal display that displays video based on the video signal output from the video processing unit 15; The decoded audio data is converted into an analog audio signal by D (Digital) / A (Analog) conversion, then amplified by an amplifier and output, and the audio signal output from the audio processing unit 17 is output. A speaker 18 that outputs sound waves, a communication unit 20 that controls communication of information between other nodes Nn and the like through the network 50, and receives an instruction from the user and sends an instruction signal corresponding to the instruction to the control unit 11. And an input unit (for example, a keyboard, a mouse, or an operation panel) 21 to be provided and controlled The unit 11, the storage unit 12, the buffer memory 13, the decoder unit 14, the communication unit 20, and the input unit 21 are connected to each other via a bus 22. As the node Nn, a personal computer, an STB (Set Top Box), a TV receiver, or the like can be applied.

  The storage unit 12 stores the IP address and port number of a contact node that is an access destination when participating in the overlay network 60. Further, the storage unit 12 stores a stored content management table for registering information related to replicas of content stored (recorded) in the HD. In this stored content management table, a content ID for specifying a content corresponding to each replica stored in the HD, a content name, and the date and time of publication of the content are registered.

  In such a configuration, the control unit 11 performs overall control by reading and executing a program (including the node processing program and the management node processing program of the present invention) stored in the storage unit 12 or the like by the CPU. , A user node, a relay node, a root node, a cache node, a content storage node, a content input node, and a management node are processed. The node processing program and the management node processing program may be downloaded from a predetermined server on the network 50, for example, or may be recorded on a recording medium such as a CD-ROM and the drive of the recording medium You may make it read via. Further, the control unit 11 that performs processing as the node device of the present invention includes the first existence confirmation unit, the second existence confirmation unit, the duplicate data acquisition unit, the node list storage unit, the participation confirmation unit, and the node list in the present invention. Functions as update means.

[3. Content acquisition operation of node Nn]
Next, with reference to FIGS. 3 to 6, first to fourth embodiments relating to a content acquisition operation in which a node Nn preferentially acquires a content replica from within a LAN to which the node Nn is connected will be described.

<3-1 First Example>
With reference to FIG. 3, a description will be given of a first embodiment in which content replicas are acquired preferentially from within the LAN to which the self is connected.

  FIG. 3 is a conceptual diagram of a LAN (la) composed of seven computers connected via the router 7a in the first embodiment.

  When the node N1 participating in the overlay network 60 desires to obtain a replica of a certain content, first, for all other nodes N2, N18, N21, N15, N12, N10 connected to the LAN (la), Send a "save status confirmation request message" for the desired content replica <1>. Each node Nn is implemented with a broadcast-type protocol in which the “storage status confirmation request message” is distributed only to the node Nn in the LAN (la) connected via the router 7a, and is transmitted from the node N1. The “save status confirmation request message” is transmitted to all the nodes Nn in the LAN (la) via the router 7a. This message includes the node ID of the node N1 that is the transmission source and the content ID that identifies the desired content.

  When the nodes N2, N18, N21, N15, N12, and N10 in the LAN (la) receive the “storage status confirmation request message” via the router 7a, <2>, the stored content management in the storage unit 12 is performed. With reference to the table, the presence or absence of content corresponding to the content ID included in the message is confirmed.

  After confirming the presence / absence of content, each of the nodes N2, N18, N21, N15, N12, and N10 transmits a “presence / absence response message” indicating the presence / absence of content to a node that is the transmission source of the “save status confirmation request message” Transmit to N1 via the router 7a <3>.

  When the node N1 receives a “presence / absence response message” from all other nodes N2, N18, N21, N15, N12, and N10 connected to the LAN (la), <4> confirms the “presence / absence response message”. Then, the content is acquired from the node N10 or N12 having the content replica. Specifically, the node N1 transmits a content transmission request message instructing content replica transmission to the node N12 having a content replica <5>, and the node N12 receives the content transmission request message. <6> A replica of the desired content is transmitted to the message transmission source node N1 <7>. Then, the node N1 receives the content replica from the node N12 via the router 7a and stores it in the HD of the storage unit 12, and also specifies a content ID, content name, and other information for specifying the content corresponding to the acquired replica. Are registered in the stored content management table of the storage unit 12.

  Here, the case where a node having a content replica exists in the node Nn in the LAN (la) has been described with reference to FIG. 3, but the node having the content replica is connected to the LAN (la). (For example, when the node N1 receives only the “presence / absence response message” with the content “No content replica of content IDaaa” from each node N2, N18, N10... ), In accordance with the operation procedure in the overlay network 60 described above, the node N1 does not belong to another node Nn outside the LAN, that is, does not belong to the LAN (la), and belongs to another LAN (lb) or (lc). Nodes Nn belonging to and participating in the overlay network 60 (for example, the nodes N3 and N4 illustrated in FIG. 1) To get the desired content over the WAN from, etc.) ....

  In the above operation, the processing of the control unit 11 in each node Nn will be described in detail with reference to FIG.

  FIG. 4 is a flowchart showing the process of the control unit 11 in an arbitrary node Nn, which is started when, for example, the power is turned on in an arbitrary node Nn.

  First, the control unit 11 performs a process for joining the overlay network 60 and proceeds to a standby loop process (step S1). In the process of joining the overlay network 60, the control unit 11 of the node Nn acquires the IP address and port number of the contact node from the storage unit 12, and based on this, connects to the contact node via the network 50, and requests to join. A participation message (including its own node ID and node information) is transmitted. As a result, a routing table using DHT is transmitted to the node Nn from the other nodes Nn participating in the overlay network 60, and the control unit 11 is based on the received routing table. A routing table is generated and participation in the overlay network 60 is completed. When the participation process to the overlay network 60 is completed, the control unit 11 reads the saved content management table from the storage unit 12 and expands it on the RAM.

  Next, it is determined whether or not a content acquisition process for obtaining a content replica has been instructed (for example, an instruction for obtaining a replica of a content via the input unit 21) (step S2).

  When the content acquisition processing is instructed (step S2: Yes), the control unit 11 stores “save” as an example of a confirmation message including the content ID of the content to be acquired to the other node Nn in the LAN to which the control unit 11 is connected. A “status confirmation request message” is transmitted (step S3).

  Next, the control unit 11 receives a “storage presence / absence response message” from another node Nn in the LAN, confirms the content of the message, and stores a content replica in the other node Nn in the LAN (storage node). Is determined (first existence confirmation means: step S4).

  As a result of the determination, if there is a content replica storage node in another node Nn in the LAN (step S4: Yes), the control unit 11 acquires a desired content replica from the storage node in the LAN (replicated data). Acquisition means: Step S5) When there is no content replica storage node in the other node Nn in the LAN (Step S4: No), the control unit 11 follows the operation procedure in the overlay network 60 described above, A desired content replica is acquired from the node Nn via the WAN (replica data acquisition means: step S6). Specifically, first, the control unit 11 transmits a “content location inquiry message” to check whether or not there is a node Nn (storage node) that stores a desired content replica (second existence confirmation). Means), if there is a storage node, that is, if the index information can be acquired from the root node, the storage node is assigned to the storage node based on the network address information (IP address or port number) of the storage node included in the index information. Connect, send a content send request message to request a replica, and get a replica from it.

  Subsequently, the control unit 11 performs other processing (step S7). Other processing includes processing according to an instruction from the user via the input unit 21, reception of a content location inquiry message (query), processing corresponding thereto, reception of a registration notification (publishing) message, and processing corresponding thereto Etc. are performed. In addition, since these processes are well-known, detailed description is abbreviate | omitted.

  As a result of the determination in step S2, if the content acquisition process is not instructed (step S2: No), the control unit 11 instructs the content providing process for providing content to other nodes Nn in and outside the LAN. It is determined whether or not (for example, a content transmission request message instructing content transmission has been received from another node Nn inside or outside the LAN) (step S8), and when content provision processing is instructed (step S8) The control unit 11 transmits a content replica to the instructing node Nn (step S9), and proceeds to step S7.

  On the other hand, as a result of the determination in step S8, if the content providing process is not instructed (step S8: No), the control unit 11 has received the “save status confirmation request message” of the content replica from the other node Nn in the LAN. (Step S10), and when a “save status confirmation request message” of a content replica is received from another node Nn (Step S10: Yes), the control unit 11 manages the stored content in the storage unit 12. With reference to the table, the presence or absence of content corresponding to the content ID included in the message is confirmed. Then, after confirming the presence / absence of the content, the control unit 11 transmits a “presence / absence response message” informing the presence / absence of the content to the node Nn in the LAN that is the transmission source of the “save status confirmation request message” (Step S11). S11), the process proceeds to step S7.

  Then, when there is a power-off instruction (for example, a power-off operation instruction from the user via the input unit 21), the control unit 11 ends the standby loop (steps S1 to S12) and the overlay network 60. If the user has joined the network, the user leaves the overlay network 60 and ends the process. On the other hand, the standby loop (steps S1 to S12) is repeatedly executed until a power-off instruction is given.

  As described above, according to the first embodiment, when a node Nn desires to obtain a content replica, the content replica is preferentially obtained from other nodes Nn in the LAN to which the node Nn is connected. Only when another node Nn in the LAN to which it is connected does not store the desired content, it is another node Nn outside the LAN to which it is connected, for example, a node Nn that is connected to another LAN. Since the content replica is acquired from the node Nn participating in the overlay network 60, it is possible to reduce the concentration of the load on the communication path on the WAN side when the content data is exchanged between the nodes Nn. Thus, the operation efficiency of the system can be improved.

<3-2 Second Example>
Next, a second embodiment in which content is preferentially acquired from within the LAN to which it is connected will be described with reference to FIGS.

  In the first embodiment described above, when acquiring content, the node Nn transmits a “save status confirmation request message” to all the nodes Nn in the LAN to which the node Nn is connected by broadcast transmission. In the present embodiment, it is confirmed whether or not the desired content replica is stored. However, in this embodiment, only the node Nn participating in the overlay network 60 among the nodes Nn in the LAN to which the self content is connected is displayed. Is transmitted to confirm whether or not a desired content replica is stored.

  In the second embodiment, each node Nn is a “P2P participation list describing information such as network address information of nodes Nn participating in the overlay network 60 among other nodes Nn in the LAN to which the node Nn is connected. Is created and stored in the storage unit 12.

  Table 1 shows an example of the P2P participation list created and stored in the storage unit 12 of the node N1.

  The P2P participation list stored by the node N1 identifies the nodes N2, N18, N15, N12, and N10 participating in the overlay network 60 among the other nodes Nn of the LAN (la) to which the node N1 is connected. Node ID, node ID (N2), node ID (N18), node ID (N15),..., And IP address as an example of network address information are described in association with each node. The node ID is a value such as 160 bits in which the bit length obtained by hashing the IP address or the serial number individually assigned to each node Nn with a common hash function (for example, SHA-1 etc.) In the overlay network 60, each node is distributed and arranged in one ID space without any bias. Further, the network address information, which is an example of the information on the node Nn described in the “P2P participation list”, may use a port number or the like specifying each node in addition to the IP address.

  Next, a method for creating the “P2P participation list” will be described.

  FIG. 5 is a conceptual diagram of a LAN (la) composed of seven computers connected via the router 7a in the second embodiment.

  First, when the node N1 participates in the overlay network 60, the overlay network 60 is sent to all the other nodes N2, N18, N21, N15, N12, and N10 that are connected to the LAN (la) to which the node N1 is connected. Broadcasts a “P2P participation status information request message” asking whether the user is participating in <1>. This message includes the node ID of the source node N1.

  When the nodes N2, N18, N21, N15, N12, and N10 in the LAN (la) receive the “P2P participation status information request message” from the node N1 via the router 7a, <2> and self-overlay A “participation presence / absence response message” informing whether or not the user is participating in the network 60 is transmitted to the node N1 via the router 7a <3>.

  Next, when the node N1 receives the “participation presence / absence response message” from all the other nodes N2, N18, N21, N15, N12, and N10 connected to the LAN (la) <4>, the “participation presence / absence response message” , A P2P participation list is created and stored in the storage unit 12.

  It should be noted that the P2P participation list is periodically updated (for example, once a day) after joining the overlay network 60 by each node Nn, even after the above-described <1> to <4> participation status to the overlay network 60 is performed. (For example, once a week).

  When the node N1 participating in the overlay network 60 desires to acquire a replica of a certain content, first, the P2P participation list in the storage unit 12 is confirmed, and all IP addresses in the list are checked (see FIG. 5). In the case of the example shown, the node “N2, N18, N15, N12, N10”) transmits the “save status confirmation request message” of the desired content replica <5>.

  Then, each node N2, N18, N15, N12, N10 receives the “save status confirmation request message” via the router 7a <6>, and refers to the saved content management table in the storage unit 12 to generate a message. The presence or absence of content corresponding to the included content ID is confirmed.

  Next, after each node N2, N18,... N10 confirms the presence / absence of content, each node N2, N18, N15, N12, N10 sends a “save status response message” informing the presence / absence of content, It transmits to the node N1 that is the transmission source of the “confirmation request message” via the router 7a <7>.

  Thereafter, similarly to the first embodiment described above, the node N1 confirms the received “presence / absence response message” <8> and acquires the content from the node Nn storing the replica of the content. The content replica request / transmission process in FIG. 5 is the same as that in the first embodiment described with reference to FIG.

  If there is no node having a replica of the desired content in the node Nn of the P2P participation list, the node N1 follows the operation procedure in the content distributed storage system S described above from other nodes Nn outside the LAN. The desired content is acquired via the WAN.

  In the above operation, the processing of the control unit 11 in each node Nn will be described in detail with reference to FIGS.

  The process shown in FIG. 6 is started when, for example, the power is turned on at an arbitrary node Nn.

  First, the control unit 11 performs a process for joining the overlay network 60 (step S21). Since the process of joining the overlay network 60 is the same as that in the first embodiment, a description thereof is omitted here.

  Subsequently, the control unit 11 transmits a “P2P participation status information request message” asking whether all nodes Nn in the LAN to which the control unit 11 is connected participates in the overlay network 60, and within the LAN to which the control unit 11 is connected. The P2P participation status information of the other node Nn is acquired (step S22). Then, according to the “participation presence / absence response message” received from the other node Nn in the LAN to which it is connected, a P2P participation list is created and stored in the storage unit 12 (node list storage means: step S23).

  Next, the process proceeds to a standby loop process (step S24), and a content acquisition process in which acquisition of a content replica is desired is instructed (for example, an instruction to acquire a replica of a certain content from the user via the input unit 21). If the content acquisition process is instructed (step S25: Yes), the P2P participation list is confirmed (step S26), and “save” as an example of a content replica confirmation message is stored. A “status confirmation request message” is transmitted according to the IP address of the P2P participation list (step S27).

  Next, the control unit 11 receives a “save presence / absence response message” from another node in the LAN, confirms the content of the message, and saves the content replica in the other node in the LAN described in the P2P participation list. It is determined whether or not there is a node (storage node) (first existence confirmation means: step S28).

  As a result of the determination, when there is a content replica storage node in another node in the LAN described in the P2P participation list (step S28: Yes), the control unit 11 selects a desired content replica from the storage node in the LAN. (Replication data acquisition means: step S29).

  On the other hand, when there is no content replica storage node in the other nodes in the LAN described in the P2P participation list (step S28: No), the control unit 11 follows the operation procedure in the overlay network 60 described above and operates outside the LAN. A desired content replica is acquired from another node Nn via the WAN (replica data acquisition means: step S30). Specifically, first, the control unit 11 transmits a “content location inquiry message” to check whether or not there is a node Nn (storage node) that stores a desired content replica (second existence confirmation). Means), if there is a storage node, that is, if the index information can be obtained from the root node, the storage is performed based on the network address information (IP address, port number) of the content storage node included in the index information. Connect to the node, send a content transmission request message to request a replica, and obtain a replica from it.

  Subsequently, the control unit 11 performs other processing (step S31). The other processes include various processes such as a process in accordance with an instruction from the user via the input unit 21, and since these processes are known as in the first embodiment, detailed description thereof is omitted.

  On the other hand, if the result of determination in step S25 is that content acquisition processing is not instructed (step S25: No), the process proceeds to step S32 in FIG. 7, and the control unit 11 transfers to another node Nn within or outside the LAN. On the other hand, it is determined whether or not a content providing process for providing content has been instructed (for example, a content transmission request message instructing content transmission is received from another node Nn within or outside the LAN) (step S32). When the providing process is instructed (step S32: Yes), the control unit 11 provides (transmits) a replica of the content to the instructing node Nn (step S33), and proceeds to step S31 in FIG. Transition.

  On the other hand, as a result of the determination in step S32, when the content providing process is not instructed (step S32: No), the control unit 11 has received the “save status confirmation request message” of the content replica from the other node Nn in the LAN. (Step S34), and when the “retention status confirmation request message” of the content replica is received from another node Nn (Step S34: Yes), the control unit 11 manages the stored content in the storage unit 12. With reference to the table, the presence or absence of content corresponding to the content ID included in the message is confirmed. Then, after confirming the presence / absence of the content, the control unit 11 transmits a “presence / absence response message” informing the presence / absence of the content to the node Nn that is the transmission source of the “storage status confirmation request message” (step S35). The process proceeds to step S31 in FIG.

  If the result of determination in step S34 is that a “save status confirmation request message” has not been received from another node Nn in the LAN (step S34: No), the controller 11 sends It is determined whether or not a “P2P participation status information request message” for inquiring whether or not it is participating in the overlay network 60 is received (step S36), and if a “P2P participation status information request message” is received (step S36) S36: Yes), the control unit 11 notifies the participation status information as to whether or not the node Nn that is the transmission source of the “P2P participation status information request message” is participating in the overlay network 60, “participation presence / absence response”. Message "is transmitted (step S37), and the process proceeds to step S31 in FIG.

  On the other hand, if the result of determination in step S36 is that a “P2P participation status information request message” has not been received from the other node Nn (step S36: No), the control unit 11 determines whether or not it is a periodic confirmation time for P2P participation status. If it is not the periodic confirmation time of the P2P participation status (step S38: No), the process proceeds to step S31 in FIG. 6, and if it is the periodic confirmation time of the P2P participation status (step S38) (S38: Yes), the P2P participation list in the storage unit 12 is confirmed (step S39), and a confirmation message for confirming whether or not the node Nn described in the P2P participation list is participating in the overlay network 60 is displayed. As an example, a “P2P participation status information request message” is transmitted, and the other node Nn in the LAN to which it is connected To get the 2P participation information (participation confirmation means: step S40).

  Next, the P2P participation list is updated based on the “participation presence / absence response message” received from the other node Nn in the LAN to which it is connected (node list update means), and stored in the storage unit 12, and then step S31 in FIG. Migrate to

  Then, when there is a power OFF instruction (for example, a power OFF operation instruction from the user via the input unit 21), the control unit 11 ends the standby loop (step S24 to step S41), and the overlay network 60. If the user has joined the network, the user leaves the overlay network 60 and ends the process. On the other hand, the standby loop (steps S24 to S41) is repeatedly executed until a power-off instruction is given.

  As described above, according to the second embodiment, when a node Nn desires to acquire a content replica, the content replica is acquired preferentially from other nodes Nn in the LAN to which the node Nn is connected. Only when another node Nn in the LAN to which it is connected does not store the desired content, it is another node Nn outside the LAN to which it is connected, such as a node Nn that is connected to another LAN. Since the content replica is acquired from the node Nn participating in the overlay network 60, it is possible to reduce the concentration of the load on the communication path on the WAN side when the content data is exchanged between the nodes Nn. be able to.

  In addition, according to the second embodiment, when the node Nn desires to obtain a replica of the content, among the nodes Nn in the LAN to which the node Nn is connected, the node Nn participating in the overlay network 60 On the other hand, since the content storage status is checked and the content replica is preferentially acquired, the configuration is such that the storage status is checked only for the node Nn that has a high possibility of acquiring the content replica. Therefore, the content replica storage status can be confirmed more efficiently.

Further, since the P2P participation list is periodically updated, it is possible to grasp the latest participation status of the other nodes Nn in the LAN to the overlay network 60.
In step S39 and step S40, the control unit 11 confirms whether or not the node Nn described in the P2P participation list is participating in the overlay network 60. The “information request message” may be broadcasted to all the nodes Nn in the LAN to acquire the P2P participation status information. At this time, if there is a newly joined node Nn, the information of the node Nn may be added to the “P2P participation list” and updated.

<3-3 Third Example>
Next, a third embodiment in which the management node manages the storage status of content replicas will be described with reference to FIGS.

  In the third embodiment, an arbitrary node Nn in the LAN is used as a management node for managing the content replica storage status, and this management node stores all the nodes Nn participating in the overlay network 60 in the LAN. It is configured to centrally manage the information. Then, when the node Nn in the LAN desires the content, a “replica management list confirmation request message” for inquiring the storage node for storing the replica of the desired content is transmitted to the management node, and the management node requests the desired content. It is assumed that the storage node of the replica of the content is taught.

  When the node Nn participates in the overlay network 60, the node Nn checks whether or not there is a management node that manages the storage status of the content replica in the LAN to which the node Nn is connected. If there is a management node, the network address information (IP address, port number), etc. of the management node is acquired, and when it is desired to acquire a replica of the content, the network address information of the management node Etc., request the storage node network address information of the desired content replica from the management node, etc., and request and acquire the desired content replica from the storage node according to the network address information of the storage node acquired from the management node To do. On the other hand, when there is no management node, the node Nn itself acquires information on the content replica stored in all the nodes Nn in the LAN, and is a node Nn in the LAN and participates in the overlay network 60. A “replica management list”, which is a list of content replicas stored in the node Nn, is created and becomes a management node.

  FIG. 8 is a conceptual diagram of a LAN (la) including seven computers connected via the router 7a in the third embodiment.

  First, when the node N1 participates in the overlay network 60, it stores the content replica in the LAN (la) for all other nodes N2, N18, N21, N15, N12, and N10 connected to the LAN (la). Broadcasting a “management node existence confirmation message” for confirming whether or not there is a management node for managing the status, that is, whether or not each node Nn is a management node participating in the overlay network 60 <1>. This message includes the node ID of the source node N1.

  When the nodes N2, N18, N21, N15, N12, and N10 in the LAN (la) receive the “management node existence confirmation message” from the node N1 via the router 7a, <2> and the self node is the management node. An answer ("is a management node" or "is not a management node") regarding the management node that informs whether or not is sent to the node N1 via the router 7a <3>. In the case of the example shown in FIG. 8, a reply that the node is a management node is transmitted from the node N10, and a reply that the node is not a management node is transmitted from the other nodes N2, N18, N21, N15, and N12. Is done. In this embodiment, the node N1 broadcasts a “management node existence confirmation message” to all the nodes in the LAN via the router 7a, but the node N21 not participating in the overlay network 60 , A reply regarding the management node may not be returned in response to the “management node existence confirmation message”.

  As described above, when the node N1 receives an answer regarding the management node from all the other nodes N2, N18, N21, N15, N12, and N10 connected to the LAN (la), <4>, whether the management node exists or not. If there is a management node, the network address information (IP address, port number) of the management node is acquired and stored in the storage unit 12. In the example shown in FIG. 8, since the node N10 is a management node, the node N1 stores the network address information of the node N10 in the storage unit 12 as the network address information of the management node.

  For example, when the node N1 participating in the overlay network 60 desires to acquire a replica of a certain content, first, the node 10 that is a management node (hereinafter referred to as “management node N10”) is desired. A “replica management list confirmation request message” is sent to inquire about the storage destination of the content replica <5>. Next, the management node N10 that has received this confirms in the replica management list the storage node Nn that stores the replica of the content corresponding to the content ID included in the “replica management list confirmation request message” <6>. Then, the management node N10 sends a “node information response message” including the network address information (IP address, port number) of the storage destination node Nn that stores the content replica to the “replica management list confirmation request message”. <7> through the router 7a to the node N1 that is the transmission source of <7>. As a result of confirmation in the replica management list, if there is no storage node that stores a replica of the content corresponding to the content ID included in the “replica management list confirmation request message”, the management node N10 has no storage node. A “node information response message” including the above information is transmitted.

  After that, the node N1 confirms the received “node information response message” <8> and acquires the content from the node Nn that stores the replica of the content, as in the first embodiment described above. To do. The content replica request / transmission processing performed between the node N1 and the storage node in FIG. 8 is the same as in the first embodiment described with reference to FIG.

  Then, when there is no node having a replica of the desired content in the node Nn described in the replica management list, that is, a “node information response message” including information indicating that there is no storage node from the management node N10. When the node N1 receives the content, the node N1 acquires the desired content from the other nodes Nn outside the LAN via the WAN according to the operation procedure in the content distributed storage system S described above.

Next, a “replica management list” created and stored by the management node will be described.
FIG. 9 is a conceptual diagram showing information exchange between the management node N10 of the LAN (la) and another node Nn in the third embodiment.

  The replica management list recognizes that there is no management node in the LAN to which the node Nn participates in the overlay network 60 or desires content, and determines that it should become the management node itself. Is created based on the control of the control unit 11.

  First, when the node N10 determines that the management node does not exist in the LAN (la) to which the node N10 is connected and should be the management node itself, the management that the node N10 will become the management node in the LAN (la). A node declaration message (including the network address information of the node N10 and the like) and a “save confirmation message” requesting information on the stored content replica are transmitted to the node Nn in the LAN (la) <1>. .

  Receiving this, each node Nn receives the management node declaration message and stores the transmitted network address information in the storage unit 12 as the network address information of the management node. Further, each node Nn follows <2> according to the received “save confirmation message” and, based on the saved content management table to be saved in the storage unit 12, all of the content replicas stored in the HD of the storage unit 12 itself. A “save / non-response message” including the content ID, the node ID as an example of the self-node information, and the network address information (IP address, port number) is transmitted to the management node N10 <3>.

  In the case of the example shown in FIG. 9, from the node N1, the node ID (N1) of the node N1, the IP address (192.168.0.8) of the node N1, and the content ID ID (aaa) of the content replica stored in the node N1, A “save presence / absence response message” including the ID (bbb) is transmitted to the management node N10, and the node N2 stores the node ID (N2) of the node N2, the IP address (192.168.0.1) of the node N2, and the node N2 A “presence / absence response message” including the content ID ID (ggg) of the content replica being sent is transmitted to the management node N10. Similarly, the “save presence / absence response message” is transmitted from the other nodes N18, N15, N12 to the management node N10.

  When the management node N10 receives the “storage presence / absence response message” from the node Nn in the LAN <4>, the management node N10 confirms the “storage presence / absence response message”, creates a replica management list, and stores it in the storage unit 12.

  In the replica management list, node IDs that identify each node, node information such as network address information, and content IDs of content replicas stored in the node are described in association with each other. This replica management list is also created including information on content replicas stored in the storage unit 12 by the management node N10 itself.

  The “save confirmation message” from the management node N10 is broadcasted to all the nodes Nn in the LAN (la) via the router 7a, and the management node N10 is sent from all the nodes Nn in the LAN (la). The node N1 has received the “presence / absence response message”, but the node N1 creates a replica management list based only on the “presence / absence response message” from the nodes N2, N18, N15, N12, and N10 participating in the overlay network 60. Alternatively, the node N21 that does not participate in the overlay network 60 may be configured not to return a “presence / absence response message” in response to the “save confirmation message” from the node N1.

  In the present embodiment, the management node Nn transmits a “save confirmation message” to all the nodes Nn in the LAN to which the management node Nn is connected, and transmits the “save confirmation message” from each node Nn to the overlay network 60. A case will be described in which a replica management list is created based only on the “presence / absence response message” from the participating node Nn.

  Table 2 shows an example of the replica management list stored in the storage unit 12 of the management node N10.

  It is desirable that the replica management list is always kept up-to-date. Therefore, in this embodiment, as a method for updating the replica management list, (A) the management node Nn periodically updates the content replica storage status to all the nodes Nn in the LAN (for example, once a day, once a week). A method of confirming and updating the replica management list (for example, once), and (B) a method of updating the replica management list by the management node Nn when each node Nn requests the management node to change the storage status of the content replica. explain.

(A) Updating the replica management list by periodic confirmation In the above operations, (A) the processing of the control unit 11 in each node Nn when the replica management list is periodically updated will be described in detail with reference to FIGS. explain.

  10 to 13 are flowcharts showing the processing of the control unit 11 in an arbitrary node Nn in the third embodiment.

  The process shown in FIG. 10 is started when, for example, the power is turned on at an arbitrary node Nn.

  First, the control unit 11 performs a process for joining the overlay network 60 (step S51). Since the process of joining the overlay network 60 is the same as that in the first embodiment, a description thereof is omitted here.

  Subsequently, the control unit 11 transmits a “management node existence confirmation message” for confirming whether or not the node is a management node participating in the overlay network 60 to all nodes Nn in the LAN to which the control unit 11 is connected (step S52). Then, a response regarding the management node that informs whether or not the node is a management node is received from another node Nn in the LAN to which it is connected, and it is determined whether or not there is a management node in the LAN (step S53).

  As a result of the determination, if the management node does not exist (step S53: No), the management node declaration message is transmitted to other nodes Nn in the LAN to which it is connected and stored so that it can become the management node. Content stored in other nodes Nn in the LAN by transmitting a “save confirmation message” requesting information on the content replica being received, receiving a “presence / absence response message” from another node Nn in the LAN Saved information is acquired (step S54).

  Then, a replica management list is created and stored in the storage unit 12 in accordance with the “save presence / absence response message” received from the other node Nn in the LAN (node list storage means: step S55). In this embodiment, the replica management list is created based on only the “presence / absence response message” from the nodes Nn participating in the overlay network 60 among the “presence / non-presence response messages” received from each node Nn. .

  Hereinafter, the process proceeds to a standby loop process from step S56, but the processes from the above-described step S54 to step S71 to be described below are processes when the self becomes a management node.

<Processing performed by the management node>
It is determined whether or not a content acquisition process desired to acquire a content replica has been instructed (for example, an instruction to acquire a replica of a content via the input unit 21) (step S57). Is instructed (step S57: Yes), the replica management list is confirmed (step S58), and the storage node storing the desired content replica is stored in another node in the LAN described in the replica management list. It is determined whether or not it exists (first existence checking means: step S59).

  As a result of the determination, if there is a content replica storage node in another node in the LAN described in the replica management list (step S59: Yes), the control unit 11 selects a desired content replica from the storage node in the LAN. (Replication data acquisition means: step S60), and if there is no content replica storage node in the other nodes in the LAN described in the replica management list (step S59: No), the control unit 11 In accordance with the operation procedure in the overlay network 60, a desired content replica is acquired from another node Nn outside the LAN via the WAN (replicated data acquisition means: step S61). Specifically, first, the control unit 11 transmits a “content location inquiry message” to check whether or not there is a node Nn (storage node) that stores a desired content replica (second existence confirmation). Means), if there is a storage node, that is, if the index information can be acquired from the root node, the storage node is assigned to the storage node based on the network address information (IP address, port number) of the storage node included in the index information. Connect, send a content send request message to request a replica, and get a replica from it.

  Subsequently, the control unit 11 performs other processing (step S62). The other processes include various processes such as a process in accordance with an instruction from the user via the input unit 21, and since these processes are known as in the first embodiment, detailed description thereof is omitted.

  As a result of the determination in step S57, when the content acquisition process is not instructed (step S57: No), the process proceeds to step S63 in FIG. 11, and the control unit 11 controls other nodes Nn within or outside the LAN. It is determined whether or not a content providing process for providing content has been instructed (for example, a content transmission request message for instructing content transmission is received from another node Nn within or outside the LAN) (step S63). Is instructed (step S63: Yes), the control unit 11 provides (transmits) a content replica to the node Nn that has instructed content transmission (step S64), and proceeds to step S62 in FIG. Transition.

  On the other hand, as a result of the determination in step S63, when the content providing process is not instructed (step S63: No), the control unit 11 inquires the storage destination of the content replica from the other node Nn in the LAN “Replica management list confirmation request” It is determined whether or not a “message” has been received (step S65), and when a “replica management list confirmation request message” is received from another node Nn (step S65: Yes), the control unit 11 If there is a storage destination node Nn that stores the replica of the content specified by the content ID included in the “replica management list confirmation request message” after checking the replica management list, the IP address of the storage node Nn "Node information response message" containing "Replica management list confirmation" If there is no storage destination node Nn that stores a replica of the content specified by the content ID included in the “request message”, a “node information response message” including information that there is no storage node is displayed in “replica management”. The “list confirmation request message” is transmitted to the transmission source node Nn (step S66), and the process proceeds to step S62 in FIG.

  If the result of determination in step S65 is that a “replica management list confirmation request message” has not been received from another node Nn (step S65: No), the control unit 11 periodically checks the storage status of the content replica. It is determined whether or not it is time (step S67), and if it is not the periodic confirmation time of the storage status of the content replica (step S67: No), the process proceeds to step S62 in FIG. (Step S67: Yes), a "save confirmation message" is transmitted to all other nodes Nn participating in the overlay network 60 in the LAN managed by the self (step S68), All content replicas stored in each node Nn from other nodes Nn Receiving the content ID, the node ID and network address information (IP address, port number) "Save existence response message" including a (step S69).

  Next, the control unit 11 updates the replica management list based on the received “presence / absence response message” (node list update means: step S70), and after storing the updated new replica management list in the storage unit 12 Then, the process proceeds to step S62 in FIG.

  Then, when there is an instruction to turn off the power (for example, a power-off operation instruction from the user via the input unit 21), the control unit 11 ends the standby loop (steps S56 to S71) and the overlay network 60. If the user has joined the network, the user leaves the overlay network 60 and ends the process. The control unit 11 repeatedly executes a standby loop (steps S56 to S71) until an instruction to turn off the power is given.

<Processing performed by managed node>
Subsequently, a case where a management node exists as a result of the determination in step S53 (step S53: Yes) will be described with reference to the flowchart of FIG. The processing in steps S81 to S99 in FIG. 12 is processing when there is a management node. When it is desired to obtain a content replica, an inquiry is made to the management node that manages the storage status of the content replica in the LAN. In other words, this is a process in which the storage node is instructed to be a managed node.

  If the result of the determination in step S53 of FIG. 10 is that there is a management node (step S53: Yes), the network address information (IP address, port number) of the management node is acquired (step S81) and stored in the storage unit 12 After saving, the process proceeds to a standby loop (step S82).

  Next, it is determined whether or not a content acquisition process for obtaining a content replica has been instructed (for example, an instruction for obtaining a replica of a content via the input unit 21) from the user (step S83). When the acquisition process is instructed (step S83: Yes), it is determined whether or not there is a management node in the LAN (step S84). Here, when the time has elapsed since the previous confirmation of the existence of the management node, it is assumed that the management node does not already exist when the content acquisition processing is instructed. ing.

  If there is no management node in the LAN (step S84: No), the process proceeds to step S52 in FIG. On the other hand, if there is a management node in the LAN (step S84: Yes), a “replica management list confirmation request message that inquires about the storage destination of the desired content replica according to the network address information of the management node stored in the storage unit 12”. "(Including the content ID of the desired content) is transmitted to the management node (step S85).

  Then, it is determined whether or not there is a storage node storing the desired content replica in another node in the LAN (first existence confirmation unit: step S86). If there is a storage node storing the desired content replica, the “node information response message” includes the network address information of the storage node, and there is no storage node storing the desired content replica. In this case, information indicating that there is no storage node is included. Therefore, when the “node information response message” including the network address information of the storage destination node Nn storing the content replica is received from the management node, there is a content replica storage node in another node in the LAN. Is determined.

  If the result of the determination is that there is a content replica storage node in another node in the LAN (step S86: Yes), the control unit 11 will store the network address of the storage node included in the "node information response message" from the management node. In accordance with the information, a desired content replica is acquired from the storage node (replica data acquisition means: step S87), and when there is no content replica storage node in another node in the LAN (step S86: No), the control unit 11 Acquires a desired content replica from another node Nn outside the LAN via the WAN in accordance with the operation procedure in the overlay network 60 described above (replicated data acquisition means: step S88). Specifically, first, the control unit 11 transmits a “content location inquiry message” to check whether or not there is a node Nn (storage node) that stores a desired content replica (second existence confirmation). Means), if there is a storage node, that is, if the index information can be obtained from the root node, the content transmission request is made by connecting to the storage node based on the IP address of the storage node included in the index information. Send a message to request a replica and get a replica from it.

  Subsequently, the control unit 11 performs other processing (step S89). The other processes include various processes such as a process in accordance with an instruction from the user via the input unit 21, and since these processes are known as in the first embodiment, detailed description thereof is omitted.

  If the result of determination in step S83 is that no content acquisition processing is instructed (step S83: No), the process proceeds to step S95 in FIG. 13, and the control unit 11 controls other nodes Nn within or outside the LAN. It is determined whether or not a content providing process for providing content has been instructed (for example, a content transmission request message for instructing content transmission is received from another node Nn in or outside the LAN) (step S95). Is instructed (step S95: Yes), the control unit 11 provides (transmits) a replica of the content to the instructing node Nn (step S96), and proceeds to step S89 in FIG. .

  On the other hand, if the content providing process is not instructed as a result of the determination in step S95 (step S95: No), has the control unit 11 received a “storage confirmation message” for confirming the storage status of the content from the management node Nn? If it is determined whether or not (step S97) and a "save confirmation message" is received from the management node Nn (step S97: Yes), the control unit 11 is based on the saved content management table stored in the storage unit 12. Then, a “save presence / absence response message” including the content IDs of all the content replicas stored in the HD of the storage unit 12 and the own node ID and the own network address information is transmitted to the management node Nn (step S98). ), The process proceeds to step S89 in FIG.

  If the “save confirmation message” for confirming the storage state of the content is not received from the management node Nn (step S97: No), the process proceeds to step S89 in FIG.

  Next, returning to the flowchart of FIG. 12, the control unit 11 performs a standby loop (steps S <b> 82 to S <b> 99) when there is a power-off instruction (for example, a power-off operation instruction via the input unit 21 from the user). When the process ends and the user joins the overlay network 60, the process leaves the overlay network 60 and ends the process. On the other hand, the standby loop (steps S82 to S99) is repeatedly executed until a power-off instruction is given.

(B) Update of replica management list by change request Subsequently, (B) control unit in each node Nn when the management node Nn updates the replica management list in response to a change request of the storage status of the content replica from each node Nn 11 will be described.

  If this process is a management node, among the processes of the control unit 11 of the node Nn described with reference to FIGS. 10 to 13, the processes of steps S67 to S70 surrounded by a broken line in FIG. If the node is a managed node, the processes in steps S97 to S98 surrounded by the one-dot chain line in FIG. 13 are replaced with the processes in steps S110 to S113 in FIG. Since the other processes are the same as those in FIGS. 10 to 13, description thereof is omitted, and only the replaced process is described here.

<Processing performed by the management node>
First, a case where the self is a management node will be described with reference to FIG.

  If the “replica management list confirmation request message” has not been received from the other node Nn in the LAN as a result of the determination in step S65 of FIG. 11 described above (step S65: No), from the other node Nn in the LAN. It is determined whether or not an information change request has been made by receiving a “presence / absence message” informing the change of the storage status of the content replica (step S100). This “presence / absence message” includes the content of the change in the storage status of the content replica, that is, the content replica has been newly stored or the stored content replica has been deleted. The content ID indicating the content replica and the network address information (IP address, port number) of the node Nn of the message transmission source are included.

  As a result of the determination, if an information change request has not been made (step S100: No), it is determined whether or not it is a periodic confirmation time for the P2P participation status (step S101). (Step S101: No), the process proceeds to Step S62 in FIG. On the other hand, if it is the periodic confirmation time of the P2P participation status (step S101: Yes), the replica management list in the storage unit 12 is confirmed (step S102), and the control unit 11 participates in the overlay network 60 in the LAN. A “P2P participation status information request message” is sent to the node Nn asking whether or not it is participating in the overlay network 60, and the P2P participation status information of the other node Nn described in the replica management list is acquired (step) S103).

  When the information change request is received from another node Nn in the LAN (step S100: Yes), the replica management list is updated according to the “participation presence / absence response message” received from the other node Nn in the LAN in step S103. Update (step S104).

  That is, when an information change request is made from another node Nn, the content of the change included in the “presence / absence message” is reflected in the replica management list and updated. In addition, it is checked whether there is a node Nn that has left the overlay network 60 with the “participation presence / absence response message” from another node Nn. If there is a node Nn that has left, the node Nn that has left the Delete and update from the management list. Then, after storing the updated replica management list in the storage unit 12, the process proceeds to step S62 in FIG.

<Processing performed by managed node>
Next, processing when the self is a managed node will be described with reference to FIG.

  If the content providing process is not instructed by another node Nn in the LAN as a result of the determination in step S95 in FIG. 13 described above (step S95: No), the control unit 11 stores the replica stored in the storage unit 12 It is determined whether or not the content replica has been changed, that is, whether or not the content replica has been newly stored or the stored content replica has been deleted (step S110). If there is a change in the replica stored in the storage unit 12 as a result of the determination (step S110: Yes), a “presence / absence message” is sent to the management node Nn informing the change of the storage status of the content replica (step S110). S111), the process proceeds to step S89 in FIG.

  On the other hand, if there is no change in the replica stored in the storage unit 12 (step S110: No), a “P2P participation status information request message” that asks whether or not the management node Nn participates in the overlay network 60 is sent. It is determined whether or not it has been received (step S112), and when the “P2P participation status information request message” has been received (step S112: Yes), the control unit 11 is directed to the overlay node 60 to the management node Nn. A “participation presence / absence response message” is sent informing the participation status information as to whether or not he / she is participating (step S113), and the process proceeds to step S89 in FIG.

  If the “P2P participation status information request message” has not been received from the management node Nn (step S112: No), the process proceeds to step S89 in FIG.

  In this embodiment, the management node Nn manages the content replica information stored in the node Nn participating in the overlay network 60 among the nodes Nn in the LAN as a replica management list. The content replica information stored by the node Nn is acquired, and the content replica information stored by all the nodes Nn in the LAN regardless of whether or not to participate in the overlay network 60 is centrally managed as a replica management list. Also good.

  In addition, the above-described (A) periodic update of the replica management list and (B) update of the replica management list based on the change request can be performed in combination.

  As described above, according to the third embodiment, the management node Nn connected in the LAN uses the content replica information stored in each node Nn participating in the overlay network 60 in the LAN as a replica management list. Since the storage unit 12 is configured to store and manage, when the node Nn in the LAN desires to acquire a replica of the content, a “node information response message” is acquired from the management node Nn, and the “node” Based on the information response message, “if there is a node Nn that stores a replica of the desired content in the LAN, the content replica is preferentially acquired from the storage node Nn and the replica of the desired content is stored. Only if the node is not in the LAN, other nodes Nn outside the LAN to which it connects, eg other L Since the node Nn connected to N is configured to acquire a content replica from the node Nn participating in the overlay network 60, the WAN side outside the LAN is used when content data is exchanged between the nodes Nn. It is possible to reduce the concentration of the load on the communication path of the system and improve the operation efficiency of the system.

  Further, according to the third embodiment, each node Nn can confirm the existence of the storage node Nn in the LAN storing a replica of the desired content only by exchanging with the management node Nn.

  Further, according to the third embodiment, the management node Nn periodically checks with each node Nn whether the replica is stored and updates the replica management list. The state can be maintained, and more accurate information can be answered to the inquiry about the storage destination of the desired content replica from each node Nn.

  Further, according to the third embodiment, each node Nn requests the management node Nn to change the storage status of the content replica when there is a change in the content replica stored by the node Nn. In this case, the management node Nn promptly reflects the storage status of the content replica in each node Nn in the replica management list in response to the information change request related to the storage presence / absence message. Since the list can be updated, accurate information can be answered in response to an inquiry about the storage destination of a desired content replica from each node Nn.

  Further, according to the third embodiment, the management node Nn is configured to periodically confirm the participation status of the overlay network 60 with respect to each node Nn in step S101, and the node Nn withdrawn from the overlay network 60 is configured. Since the information related to is deleted from the replica management list, the replica management list for managing the storage status of the content replica in the node Nn participating in the overlay network 60 in the LAN can be stored in a more accurate state. it can.

<3-4 Fourth Example>
Next, a fourth embodiment for managing the storage status of the content replica stored in the node Nn in the LAN to which the node Nn is connected will be described with reference to FIGS.

  In the third embodiment, an arbitrary node Nn in the LAN is used as a management node for managing the content replica storage status, and this management node stores all the nodes Nn participating in the overlay network 60 in the LAN. In the fourth embodiment, all nodes Nn participating in the overlay network 60 in the LAN create and store a replica management list, and each node Nn The content replica information stored in all the nodes Nn participating in the overlay network 60 connected to the LAN to which it is connected is managed.

  When the node Nn participates in the overlay network 60, the node Nn broadcasts a “save confirmation message” requesting information on the content replica stored to all the nodes Nn in the LAN to which the node Nn is connected, and is saved from each node. A “save presence / absence response message” including the information of the content replica being received is received, a replica management list is created based on this, and stored in the storage unit 12.

  FIG. 16 is a conceptual diagram of a LAN (la) including seven computers connected via the router 7a in the fourth embodiment.

  First, when the node N1 participates in the overlay network 60, the stored content replica information is stored for all the other nodes N2, N18, N21, N15, N12, and N10 connected to the LAN (la). The requested “save confirmation message” is broadcasted <1>. This message includes the node ID of the source node N1.

  Then, each node N2, N18, N21, N15, N12, N10 in the LAN (la) receives the “save confirmation message” from the node N1 via the router 7a <2> and saves it in the storage unit 12. Based on the stored content management table, a “save presence / absence response message including content IDs of all content replicas stored in the HD of the storage unit 12 and node IDs and network address information as an example of information of the self node. Is transmitted to the node N1 that is the transmission source of the “save confirmation message” <3>.

  In the case of the example shown in FIG. 9, from the node N2, the node ID (N2) of the node N2, the IP address (192.168.0.1) of the node N2, and the content ID (ggg) of the content replica stored in the node N2 A “save presence / absence response message” is transmitted to the node N1, and the node N18 sends the node ID (N18) of the node N1, the IP address (192.168.0.2) of the node N1, and the content replica stored by the node N18. A “presence / absence response message” including the content ID (bbb), ID (ccc), and ID (ddd) is transmitted to the node N1, and the “presence / absence response message” is similarly sent from the other nodes N18, N21, N15, and N12. Is transmitted to the node N1.

  When the node N1 receives the “save presence / absence response message” from all the nodes Nn in the LAN <4>, the node N1 confirms the “save presence / absence response message”, creates a replica management list, and stores it in the storage unit 12. Note that the replica management list is created including information on content replicas stored in the storage unit 12 by the node N1 itself.

  The “save confirmation message” from the node N1 is broadcasted to all the nodes Nn in the LAN (la) via the router 7a, and the node N1 sends “save” from all the nodes Nn in the LAN (la). The node N1 may receive the “presence / absence response message”, but the node N1 may be configured to create the replica management list based only on the “presence / absence response message” from the node Nn participating in the overlay network 60, or The node N21 not participating in the overlay network 60 may be configured not to return a “save / non-save response message” in response to the “save confirmation message” from the node N1.

  In this embodiment, each node Nn transmits a “save confirmation message” to all nodes Nn in the LAN to which the node Nn is connected, and among the “save presence / absence response messages” from each node Nn, A case will be described in which a replica management list is created based only on the “presence / absence response message” from the participating node Nn.

  In addition, the replica management list stored in the storage unit 12 of the node N1 in this embodiment is the same as that in Table 2.

  In the above operation, (A) a method of periodically checking the storage status of content replicas for all nodes Nn participating in the overlay network 60 in the LAN and updating the replica management list at each node Nn; (B) A method in which each node Nn updates the replica management list by making a change request to each node Nn when there is a change in the storage status of the content replica stored by each node Nn. Explain each one.

(A) Updating the replica management list by periodic confirmation In the above operations, (A) the processing of the control unit 11 in each node Nn when the replica management list is periodically updated will be described with reference to FIG. 17 and FIG. explain in detail.

  17 and 18 are flowcharts showing the processing of the control unit 11 in an arbitrary node Nn.

  The process shown in FIG. 17 is started when, for example, the power is turned on at an arbitrary node Nn.

  First, the control unit 11 performs a process for joining the overlay network 60 (step S201). Since the process of joining the overlay network 60 is the same as that in the first embodiment, a description thereof is omitted here.

  Subsequently, as described above with reference to FIG. 16, the control unit 11 sends a “save confirmation message” requesting information on the stored content replicas to all the nodes Nn in the LAN to which the control unit 11 is connected. The content storage information stored in the other nodes Nn participating in the overlay network 60 in the LAN is acquired by receiving the “save presence / absence response message” from each node Nn (step S202).

  Then, a replica management list is created and stored in the storage unit 12 according to the “save presence / absence response message” received from the other node Nn participating in the overlay network 60 in the LAN (node list storage means: step S203).

  Thereafter, the process proceeds to a standby loop process from step S204, and a content acquisition process for obtaining a content replica is instructed (for example, an instruction for obtaining a replica of a content via the input unit 21). If the content acquisition process is instructed (step S205: Yes), the replica management list is confirmed (step S206), and other nodes in the LAN described in the replica management list are checked. It is determined whether or not there is a storage node storing the desired content replica (first existence confirmation unit: step S207).

  As a result of the determination, if there is a content replica storage node in another node in the LAN described in the replica management list (step S207: Yes), the control unit 11 selects a desired content replica from the storage node in the LAN. Is acquired (replication data acquisition means: step S208).

  On the other hand, when there is no content replica storage node in the other nodes in the LAN described in the replica management list (step S207: No), the control unit 11 follows the operation procedure in the overlay network 60 described above, A desired content replica is acquired from another node Nn via the WAN (replicated data acquisition means: step S209). Specifically, first, the control unit 11 transmits a “content location inquiry message” to check whether or not there is a node Nn (storage node) that stores a desired content replica (second existence confirmation). Means), if there is a storage node, that is, if the index information can be acquired from the root node, the storage node is assigned to the storage node based on the network address information (IP address, port number) of the storage node included in the index information. Connect, send a content send request message to request a replica, and get a replica from it.

  Subsequently, the control unit 11 performs other processing (step S210). The other processes include various processes such as a process in accordance with an instruction from the user via the input unit 21, and since these processes are known as in the first embodiment, detailed description thereof is omitted.

  As a result of the determination in step S205, when the content acquisition process is not instructed (step S205: No), the process proceeds to step S220 in FIG. 18, and the control unit 11 controls other nodes Nn within or outside the LAN. It is determined whether or not a content providing process for providing content has been instructed (for example, a content transmission request message for instructing content transmission is received from another node Nn in or outside the LAN) (step S220), and the content providing process Is instructed (step S220: Yes), the control unit 11 provides (transmits) a content replica to the node Nn that has instructed content transmission (step S221), and proceeds to step S210 in FIG. Transition.

  On the other hand, as a result of the determination in step S220, if the content providing process is not instructed (step S220: No), the control unit 11 confirms the storage status of the content from another node Nn in the LAN “storage confirmation message”. Is received (step S222), and when the “save confirmation message” is received (step S222: Yes), the control unit 11 is based on the saved content management table stored in the storage unit 12. , “Save Presence Response Message” including the content IDs of all content replicas stored in the HD of the storage unit 12, its own node ID, and its own network address information (IP address, port number). The “confirmation message” is transmitted to the other node Nn of the transmission source (step S223), and FIG. The process proceeds to step S210.

  If the “save confirmation message” for confirming the storage status of the content is not received from another node Nn in the LAN (step S222: No), the control unit 11 periodically checks the storage status of the content replica. It is determined whether or not it is time (step S224), and if it is not the periodic confirmation time of the storage status of the content replica (step S67: No), the process proceeds to step S62 in FIG. (Step S224: Yes), a “save confirmation message” is broadcasted to all other nodes Nn in the LAN to which it is connected (step S68). From each node Nn to each node Nn Content IDs, node IDs and network IDs of all content replicas Address information (IP address, port number) including receiving a "Save existence response message" (step S226).

  Next, the control unit 11 updates the replica management list based on the received “presence / absence response message” (node list update means: step S227), and after storing the updated new replica management list in the storage unit 12 Then, the process proceeds to step S210 in FIG.

  Subsequently, the control unit 11 performs other processing (step S228). The other processes include various processes such as a process in accordance with an instruction from the user via the input unit 21, and since these processes are known as in the first embodiment, detailed description thereof is omitted.

  Then, when there is a power-off instruction (for example, a power-off operation instruction from the user via the input unit 21), the control unit 11 ends the standby loop (steps S204 to S228) and the overlay network 60. If the user has joined the network, the user leaves the overlay network 60 and ends the process. The control unit 11 repeatedly executes a standby loop (step S204 to step S228) until an instruction to turn off the power is given.

(B) Update of replica management list by change request Subsequently, (B) a control unit in each node Nn when each node Nn updates the replica management list in response to a change request of the storage status of the content replica from each node Nn 11 will be described in detail with reference to FIG.

  This process includes steps S222 to S227 surrounded by a broken line in FIG. 18 among the processes of the control unit 11 of the node Nn described with reference to FIGS. The processing is replaced with the processing of S260, and the other processing is the same as the processing of FIG. 17 and FIG.

  In FIG. 19, when content provision processing is instructed (step S250: Yes), a content replica is provided (transmitted) to the instructed node Nn (step S251). Note that the details of the processing of S250 and S251 are the same as the processing of Step S220 and Step S221 described above, and a description thereof will be omitted.

  If the content providing process is not instructed as a result of the determination in step S250 (step S250: No), the control unit 11 determines whether or not the content replica stored in the storage unit 12 has changed, that is, the content replica. Is newly stored or whether the stored content replica is deleted is determined (step S252). As a result of the determination, if there is a change in the content replica stored in the storage unit 12 (step S253: Yes), a “presence / absence message” that notifies the change of the storage status of the content replica is sent to each node Nn in the LAN. (Step S254), and the process proceeds to step S210 in FIG.

  On the other hand, when there is no change in the content replica stored in the storage unit 12 (step S253: No), it is asked whether or not the node Nn in the LAN is participating in the overlay network 60 "P2P participation status" It is determined whether or not the “information request message” has been received (step S254), and when the “P2P participation status information request message” has been received (step S254: Yes), the control unit 11 transmits to the transmission source node Nn. On the other hand, a “participation presence / absence response message” informing the participation status information as to whether or not he / she is participating in the overlay network 60 is transmitted (step S255), and the process proceeds to step S210 in FIG.

  If the “P2P participation status information request message” has not been received from any node Nn in the LAN (step S254: No), a “presence / absence message” that informs the change of the content replica from the other node Nn is displayed. It is determined whether or not an information change request has been received (step S256). This “presence / absence message” includes the content of the change in the storage status of the content replica, that is, the content replica has been newly stored or the stored content replica has been deleted. The content ID indicating the content replica and the network address information of the message transmission source node Nn are included.

  As a result of the determination, if an information change request has not been made (step S256: No), it is determined whether or not it is a regular confirmation time for the P2P participation status (step S257). (Step S257: No), the process proceeds to Step S210 in FIG.

  On the other hand, if it is the periodic confirmation time of the P2P participation status (step S257: Yes), the replica management list in the storage unit 12 is confirmed (step S258), and the control unit 11 determines the node Nn described in the replica management list. In response to this, a “P2P participation status information request message” asking whether or not the participant is participating in the overlay network 60 is transmitted, and the P2P participation status information of the other node Nn described in the replica management list is acquired (step S259). .

  When the information change request is received from another node Nn (step S256: Yes), the replica management list is updated according to the “participation presence / absence response message” received from the other node Nn in step S259 (step S260). . That is, when an information change request is made from another node Nn, the content of the change included in the “presence / absence message” is reflected in the replica management list and updated. In addition, it is checked whether there is a node Nn that has left the overlay network 60 with the “participation presence / absence response message” from another node Nn. If there is a node Nn that has left, the node Nn that has left the Delete and update from the management list. Thereafter, the process proceeds to step S210 in FIG.

  In this embodiment, each node Nn manages the content replica information stored in the node Nn participating in the overlay network 60 among the nodes Nn in the LAN as a replica management list. The content replica information stored by the node Nn may be acquired, and the content replica information stored by all the nodes Nn in the LAN may be managed as a replica management list regardless of whether or not to participate in the overlay network 60. Good.

  In addition, the above-described (A) periodic update of the replica management list and (B) update of the replica management list based on the change request can be performed in combination.

  As described above, according to the fourth embodiment, each node Nn stores, as a replica management list, information on content replicas stored by each node Nn participating in the overlay network 60 in the LAN to which it is connected. 12, when the node Nn in the LAN desires to acquire a content replica, the content replica is stored from the storage node Nn that stores the desired content replica based on the replica management list. Only if there is no node Nn in the LAN that stores the replica of the desired content and is not in the LAN, for example, a node Nn that is connected to another LAN, for example, a node Nn connected to another LAN. , Get replica of content from node Nn participating in overlay network 60 Having so that configuration, when transmitting and receiving contents data between nodes Nn, to reduce that load on the communication path of the WAN side is concentrated, it is possible to improve the operational efficiency of the system.

  Further, according to the fourth embodiment, each node Nn periodically checks the contents of the replica management list with respect to each node Nn and updates the replica management list, so that the replica management list is updated. Can be kept in the state.

  Furthermore, according to the fourth embodiment, each node Nn is configured to request each node Nn to change the storage status of the content replica when there is a change in the content replica stored by itself. Therefore, when there is a change request from any of the nodes Nn, each node Nn can quickly reflect the storage status of the content replica in the replica management list according to the change request.

  Furthermore, according to the fourth embodiment, each node Nn is configured to periodically check the participation status of each node Nn participating in the overlay network 60 in the LAN to which it is connected to the overlay network 60, Since the information related to the node Nn withdrawn from the overlay network 60 is deleted from the replica management list, the replica management list for managing the storage status of the content replica in the node Nn participating in the overlay network 60 in the LAN is more accurate. Can be stored in the state.

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

It is a figure which shows an example of the connection aspect of each node apparatus in the content distributed storage system which concerns on this embodiment. It is a figure which shows the example of an outline structure of the node Nn. It is a conceptual diagram of LAN (la) which consists of seven computers connected via the router 7a in a 1st Example. It is a flowchart which shows the process of the control part 11 in arbitrary nodes Nn in a 1st Example. It is a conceptual diagram of LAN (la) which consists of seven computers connected via the router 7a in a 2nd Example. It is a flowchart which shows the process of the control part 11 in arbitrary nodes Nn in a 2nd Example. It is a flowchart which shows the process of the control part 11 in arbitrary nodes Nn in a 2nd Example. It is a conceptual diagram of LAN (la) which consists of seven computers connected via the router 7a in a 3rd Example. It is a conceptual diagram which shows transmission / reception of the management node N10 of LAN (la) in the 3rd Example, and the other node Nn. It is a flowchart which shows the process of the control part 11 in arbitrary nodes Nn in a 3rd Example. It is a flowchart which shows the process of the control part 11 in arbitrary nodes Nn in a 3rd Example. It is a flowchart which shows the process of the control part 11 in arbitrary nodes Nn in a 3rd Example. It is a flowchart which shows the process of the control part 11 in arbitrary nodes Nn in a 3rd Example. It is a flowchart which shows the process of the control part 11 in arbitrary nodes Nn in a 3rd Example. It is a flowchart which shows the process of the control part 11 in arbitrary nodes Nn in a 3rd Example. It is a conceptual diagram of LAN (la) which consists of seven computers connected via the router 7a in a 4th Example. It is a flowchart which shows the process of the control part 11 in arbitrary nodes Nn in a 4th Example. It is a flowchart which shows the process of the control part 11 in arbitrary nodes Nn in a 4th Example. It is a flowchart which shows the process of the control part 11 in arbitrary nodes Nn in a 4th Example.

Explanation of symbols

50 Network 60 Overlay Network 11 Control Unit 12 Storage Unit 13 Buffer Memory 14 Decoder Unit 15 Video Processing Unit 16 Display Unit 17 Audio Processing Unit 18 Speaker 20 Communication Unit 21 Input Unit 22 Bus Nn Node S Content Distributed Storage System

Claims (14)

A plurality of local area networks to which a plurality of node devices are connected, a network in which the plurality of local area networks are connected to each other via a communication unit; One of the node devices included in a content distributed storage system that is stored in a distributed manner and that allows the replicated data to be exchanged between the node devices,
A first node that checks whether there is another node device that stores the duplicate data of the content to be acquired and that is connected to the local area network to which it is connected Existence confirmation means,
When the other node device does not exist, the other node device stores the duplicate data, and is connected to another local area network different from the local area network to which the node device is connected. Second existence confirmation means for confirming whether or not another node device exists;
Replicated data acquisition means for requesting and acquiring the replicated data from other node devices whose existence has been confirmed,
A node device comprising: The node device according to claim 1,
The first existence confirmation means transmits a confirmation message that is distributed only to other node devices connected to the local area network to which the first existence confirmation unit is connected, and receives the confirmation message from the other node device. A node that confirms whether or not there is another node device that stores the copy data by receiving a storage presence / absence response message indicating whether or not the copy data of the returned content is stored apparatus. The node device according to claim 1,
A node device that participates in the distributed content storage system as a node device capable of sending and receiving the replicated data, and describes the information of the other node device connected to the local area network to which it is connected Node list storage means for storing the list;
The first presence confirmation unit transmits a confirmation message that is distributed only to other node devices whose information is described in the node list, and is returned from the other node device that has received the confirmation message. A node device characterized in that, by receiving a storage presence / absence response message indicating whether or not content copy data is stored, it is confirmed whether there is another node device storing the copy data. The node device according to claim 3, wherein
The content distribution returned from the other node device that has transmitted the confirmation message periodically to only the other node devices connected to the local area network to which it is connected Participation confirmation means for receiving a participation presence / absence response message indicating whether or not to participate in the storage system;
Node list update means for updating the node list based on the received participation presence / absence response message;
A node device further comprising: The local area network includes information on node devices participating in the distributed content storage system as node devices that can exchange the replicated data among node devices connected to the local area network, and the content of the content in the node devices. A management node device that centrally manages information indicating the presence or absence of storage of replicated data is connected,
The first existence confirmation unit transmits a confirmation message to the management node device connected to the local area network to which the first existence confirmation unit is connected, and is returned from the management node device that has received the confirmation message. Receiving a node information response message indicating information of a node device storing the copy data of the content, thereby confirming whether there is another node device storing the copy data; The node device according to claim 1. A management node device that receives the confirmation message from the node device according to claim 5,
Among the node devices connected to the local area network to which it is connected, information on the node device that participates in the content distributed storage system as a node device that can exchange the duplicate data, and the duplicate data of the content in the node device Node list storage means for storing a node list in which information indicating whether or not to store is described;
Periodically send a confirmation message to only other node devices connected to the local area network to which it is connected, and return the content returned from the other node device that received the confirmation message. A content presence / absence confirmation means for receiving a storage presence / absence response message indicating whether or not the copy data is stored;
Node list update means for updating the node list based on the received storage presence / absence response message;
A management node device comprising: A management node device that receives the confirmation message from the node device according to claim 5,
Among the node devices connected to the local area network to which it is connected, information on the node device that participates in the content distributed storage system as a node device that can exchange the duplicate data, and the duplicate data of the content in the node device Node list storage means for storing a node list in which information indicating whether or not to store is described;
Presence / absence of storage indicating whether or not to store the duplicate data transmitted from the node device when the duplicate data is newly saved or deleted in the node device whose information is described in the node list Message receiving means;
Node list update means for updating the node list based on the received storage presence / absence message;
A management node device comprising: The node device according to claim 1,
Among the node devices connected to the local area network to which it is connected, information on the node device that participates in the content distributed storage system as a node device that can exchange the duplicate data, and the duplicate data of the content in the node device And a node list storage means for storing a node list in which information indicating whether or not to store is described,
The node device according to claim 1, wherein the first existence confirmation unit confirms whether or not there is another node device storing the duplicated data by referring to the node list. The node device according to claim 7, wherein
Periodically send a confirmation message to only other node devices connected to the local area network to which it is connected, and return the content returned from the other node device that received the confirmation message. A content presence / absence confirmation means for receiving a storage presence / absence response message indicating whether or not the copy data is stored;
Node list update means for updating the node list based on the received storage presence / absence response message;
A node device comprising: The node device according to claim 7, wherein
Presence / absence of storage indicating whether or not to store the duplicate data transmitted from the node device when the duplicate data is newly saved or deleted in the node device whose information is described in the node list Message receiving means;
Node list update means for updating the node list based on the received storage presence / absence message;
A node device comprising:   A node processing program for causing a computer to function as the node device according to any one of claims 1 to 5 and 8 to 10.   A management node processing program for causing a computer to function as the management node device according to claim 6 or 7. A plurality of local area networks to which a plurality of node devices are connected, a network in which the plurality of local area networks are connected to each other via a communication unit; In a distributed content storage system that is stored in a distributed manner and that allows the replicated data to be exchanged between each node device,
One of the node devices is
A first node that checks whether there is another node device that stores the duplicate data of the content to be acquired and that is connected to the local area network to which it is connected Existence confirmation means,
When the other node device does not exist, the other node device stores the duplicate data, and is connected to another local area network different from the local area network to which the node device is connected. Second existence confirmation means for confirming whether or not another node device exists;
Replicated data acquisition means for requesting and acquiring the replicated data from other node devices whose existence has been confirmed,
A content distributed storage system comprising: A plurality of local area networks to which a plurality of node devices are connected, a network in which the plurality of local area networks are connected to each other via a communication unit; A method for obtaining duplicate data in a distributed content storage system that is stored in a distributed manner and allows the duplicate data to be exchanged between the respective node devices,
One of the node devices is
A step of confirming whether there is another node device that stores the duplicate data of the content to be acquired and is connected to the local area network to which the device is connected;
When the other node device does not exist, the other node device stores the duplicate data, and is connected to another local area network different from the local area network to which the node device is connected. A step of checking whether or not another node device exists;
Requesting and obtaining the duplicated data from another node device whose existence has been confirmed; and
A duplicate data acquisition method comprising:

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