JP2012050020A - Communication system, information processing device, information processing program, and location information registration method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system, an information processing device, an information processing program, and a location information registration method which utilize the merit of a resident node participating in an overlay network, even when the overlay network has the resident node and a general node mixed therein.SOLUTION: An information processing device receives a message, sent by another information processing device via an overlay network, including location information of the other information processing device and device identification information showing that the other information processing device is a first information processing device or a second information processing device different from the first information processing device. Then, based on the device identification information included in the received message, the information processing device prioritizes the location information included in the message when the device identification information shows the first information processing device, to register it in a routing table.

Description

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

  In recent years, a peer-to-peer distribution system has been known. In a peer-to-peer distribution system, a plurality of content data are distributed and stored in an overlay network composed of a plurality of node devices. In the overlay network, the node device can acquire content data from other node devices. The content data is hereinafter referred to as “content”. The node device is hereinafter referred to as a “node”. In such a peer-to-peer distribution system, it is possible to reduce the load concentration on the server as in the client-server distribution system. The location of content distributed and stored in the overlay network can be efficiently searched using a routing table using a distributed hash table as disclosed in Patent Document 1, for example.

JP 2006-197400 A

  By the way, a resident node and a general node may be mixed in a plurality of nodes participating in the overlay network. Here, the resident node is a node that regularly participates in the overlay network. On the other hand, a general node is a node that does not always participate in the overlay network regularly. The general node is a node that repeatedly joins and leaves the overlay network. Here, “withdrawal” is also referred to as “withdrawal”.

  In the case of an overlay network in which resident nodes and general nodes are mixed, basically, if an overlay network is configured with resident nodes, communication on the overlay network is stable. Here, the communication on the overlay network includes, for example, message transmission / reception between nodes performed via the overlay network.

  However, when the number of general nodes participating in the overlay network increases, communication on the overlay network may become unstable. For example, when a general node leaves the overlay network, a node holding a routing table for registering the IP address of the general node cannot transmit a message to the detached general node. Therefore, a node that holds a routing table for registering an IP address or the like of a general node must perform processing for transmitting a message to another node again. If communication on the overlay network becomes unstable in this way, the advantage that the resident node participates in the overlay network cannot be utilized.

  Therefore, the present invention has been made in view of the above points and the like, and even in an overlay network in which resident nodes and general nodes are mixed, it is possible to take advantage of the resident nodes participating in the overlay network. It is an object to provide a possible communication system, information processing apparatus, information processing program, and location information registration method.

  In order to solve the above-described problem, the invention according to claim 1 is a communication system in which an overlay network is configured by a plurality of information processing devices capable of communicating with each other via a network, wherein the information processing device includes the overlay network. Including a first information processing device set as a device that contributes to the operation of the information processing device and a second information processing device that is different from the first information processing device. A storage means for storing location information indicating location information in a message, a message transmitted from another information processing device via the overlay network, and the location information of the other information processing device , Indicating that the other information processing apparatus is the first information processing apparatus or the second information processing apparatus First receiving means for receiving the message including device identification information, and the device identification information indicating the first information processing device based on the device identification information included in the received message. And determining means for determining that the location information included in the message is preferentially registered in the routing table.

  According to a second aspect of the present invention, in the communication system according to the first aspect, the information processing apparatus is configured to receive another information processing apparatus via the overlay network based on the location information registered in the routing table. A first transmission unit that transmits a message to the determination unit, and a determination unit that determines whether or not the information processing device that transmits the message by the first transmission unit satisfies a condition of the set first information processing device; A second determination for determining whether the information processing apparatus transmitting the message by the first transmission means is the first information processing apparatus or the second information processing apparatus based on a determination result by the determination means; Means, wherein the first transmission means transmits the message by the first transmission means, the location information of the information processing apparatus, and the second determination means. And transmitting the message including the device identification information indicating the first information processing device or the second information processing device determined to the second information processing device, and the message included in the message When the first information processing device is indicated in the device identification information, the determination unit determines to register the location information included in the message, and the information processing device uses the determination unit to determine the location information. When the registration is determined, registration means for registering the location information in the routing table is further provided.

  According to a third aspect of the present invention, in the communication system according to the second aspect, the routing table has a plurality of registration areas for registering the location information, and the device identification information included in the message includes In the case where the first information processing apparatus is shown and the location information of the second information processing apparatus is already registered in the registration area for registering the location information, It is determined that the location information included in the message is registered with priority over the location information registered in the registration area.

  According to a fourth aspect of the present invention, in the communication system according to the second aspect, the determination unit is configured such that the information processing apparatus that transmits a message by the first transmission unit is the set first information processing apparatus. It is determined whether or not the time that has been participating in the overlay network is a predetermined time or more as a condition of the above, and the second determination means determines that the determination means is more than a predetermined time, The information processing apparatus that transmits a message by the first transmission unit is determined to be the first information processing apparatus.

According to a fifth aspect of the present invention, in the communication system according to the second aspect, the determination unit is configured such that the information processing apparatus that transmits a message by the first transmission unit is the set first information processing apparatus. (1) The storage capacity of the storage area for storing the content provided in the storage unit included in the information processing apparatus is greater than or equal to a predetermined capacity. (2) Connected to the communication unit included in the information processing apparatus. (3) Connection of TCP (Transmission Control Protocol) / IP (Internet Protocol) or UDP (User Datagram Protocol) / IP from another device connected to the network. The second determination means determines whether or not any one of the items (1) to (3) is satisfied by the determination means. If it is determined that the condition is satisfied, the first transmitting means and said information processing apparatus for transmitting a message by, characterized in that determining said a first information processing apparatus.

  The invention according to claim 6 is the communication system according to any one of claims 1 to 5, wherein the first information processing apparatus is a node apparatus that regularly participates in the overlay network, The second information processing apparatus is a node apparatus that joins or leaves the overlay network at an arbitrary timing.

  The invention according to claim 7 is the communication system according to any one of claims 1 to 6, wherein the information processing apparatus participating in the overlay network receives a participation message indicating a request to participate in the overlay network. The apparatus further comprises second transmission means for transmitting to the predetermined first information processing apparatus, wherein the first information processing apparatus includes a second reception means for receiving a participation message transmitted from the information processing apparatus, and a predetermined number A fourth acquisition means for acquiring a predetermined number of the location information from a routing table for registering the location information of the first information processing apparatus; and A third transmission means for transmitting to the transmitted information processing apparatus, wherein the information processing apparatus participating in the overlay network is the first Third storage means for receiving the predetermined number of the location information transmitted from the information processing device, and the storage means based on the predetermined number of the location information received by the third reception means 5th acquisition means which acquires the said routing table, Comprising: The said routing table which registers the said location information of a said 1st information processing apparatus preferentially, It is characterized by the above-mentioned.

  The invention according to claim 8 is a communication system in which an overlay network is configured by a plurality of information processing devices that can communicate with each other via a network, wherein the information processing device is set as a device that contributes to the operation of the overlay network. The information processing apparatus includes a storage unit that stores a routing table for registering location information indicating the location of the information processing apparatus on the network, and the overlay from another information processing apparatus. A message transmitted via a network, wherein the location information of the other information processing device and the second information processing device are different from the first information processing device or the first information processing device. First receiving means for receiving the message including device identification information indicating that the information processing device is Based on the device identification information included in the received message, the location information included in the message when the device identification information indicates the first information processing device is given priority in the routing table. And determining means for determining registration.

  The invention according to claim 9 is a communication system in which an overlay network is configured by a plurality of information processing devices that can communicate with each other via a network, and the information processing device is set as a device that contributes to the operation of the overlay network. Storing a routing table for registering location information indicating the location of the information processing device on the network, in the computer included in the information processing device, and the other information processing device A message transmitted from the information processing apparatus via the overlay network, and the other information processing apparatus and the first information processing apparatus or the first information processing apparatus. The message including device identification information indicating a different second information processing device On the basis of the device identification information included in the received message and the location information included in the message when the device identification information indicates the first information processing device, based on the device identification information included in the received message, And an information processing program for executing the step of determining registration in the routing table.

  The invention according to claim 10 is a location information registration method in a communication system in which an overlay network is configured by a plurality of information processing devices that can communicate with each other via a network, wherein the information processing device Including a first information processing device set as a device that contributes to operation, wherein the location information registration method stores a routing table for registering location information indicating the location of the information processing device on the network; Messages transmitted from the information processing apparatus via the overlay network, and the location information of the other information processing apparatus and the other information processing apparatus are the first information processing apparatus or the first information processing apparatus. Including the device identification information indicating that the second information processing device is different from the information processing device. And receiving location information included in the message when the device identification information indicates the first information processing device based on the device identification information included in the received message. And determining to register in the routing table.

  According to the first, sixth, and eighth to tenth aspects of the present invention, an information processing apparatus that has received a message from another information processing apparatus includes the first information processing included in the message. Based on the device identification information indicating that the device is the device or the second information processing device, the location information included in the message when the device identification information indicates the first information processing device is given priority, Decide to register in the routing table. For this reason, it is possible to stabilize communication on the overlay network in which the first information processing apparatus and the second information processing apparatus are mixed. Therefore, the merit that the first information processing apparatus participates in the overlay network can be utilized.

  According to the second aspect of the present invention, the information processing apparatus that has received the message quickly confirms whether the information processing apparatus that has transmitted the message is the first information processing apparatus or the second information processing apparatus. Can do. Further, the routing table stored in the information processing apparatus can be a routing table for registering the location information of the first information processing apparatus. For this reason, it is possible to stabilize communication on the overlay network.

  According to the third aspect of the present invention, even when the location information of the first information processing apparatus and the second information processing apparatus is registered in the routing table stored in the information processing apparatus, The location information of the information processing apparatus can be updated to the routing table.

  According to the invention described in claim 4, it is possible to automatically determine an appropriate information processing apparatus as an apparatus that contributes to the operation of the overlay network ON.

  According to the fifth aspect of the present invention, it is possible to automatically determine an appropriate information processing apparatus as an apparatus that contributes to the operation of the overlay network ON.

  According to the seventh aspect of the present invention, when the information processing apparatus participates in the overlay network, it can obtain a routing table that preferentially registers the location information of the first information processing apparatus.

It is a figure showing an example of outline composition of a contents distribution system concerning this embodiment. (A) is a figure showing an example in which a publish message is transmitted from a content holding node to a root node by DHT routing. (B) is a diagram showing an example in which a periodic publish message is transmitted from the content holding node to the root node by DHT routing. (C) is a diagram illustrating an example in which a route change confirmation message is transmitted from the forwarding node X to the root node by DHT routing. (D) is a diagram illustrating a schematic configuration example of a router Rm. (E) is a block diagram illustrating a schematic configuration example of the user terminal To. (A) is a flowchart showing main processing in the node Nn. (B) is a flowchart showing details of message transmission processing in step S8 of (A). FIG. 3A is a flowchart illustrating details of message reception processing in step S10 of FIG. (B) is an example of a routing table stored in the node Nn that has received the message. It is a flowchart which shows the detail of the message reception process in step S10 of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiment described below is an embodiment when the present invention is applied to a content distribution system.

[ 1. Content distribution system configuration and operation overview ]
First, with reference to FIG. 1, the structure and operation | movement outline | summary of the content delivery system which concerns on this embodiment are demonstrated. FIG. 1 is a diagram illustrating a schematic configuration example of a content distribution system S according to the present embodiment. The content distribution system is an example of a communication system according to the present invention. As shown in FIG. 1, the content distribution system S according to the present embodiment includes a router Rm (m = 1, 2, 3... J) and a user terminal UTo (o = 1, 2, 3. ) And the like. The router Rm is connected to a network NW composed of the Internet or the like. The user terminal UTo is, for example, a personal computer or a portable device used by the user. For example, the user terminal UTo can be connected to the network NW using an IP address assigned by a server (not shown) of an Internet service provider.

  In addition, as shown in FIG. 1, in the content distribution system S, a base network NLm is constructed for each of a plurality of bases Pm. Examples of the base include a karaoke store, a school, a company, a house, and other facilities. The base network NLm is a private network such as a LAN (Local Area Network). Also, a router Rm and a plurality of base terminals Tm-l (l = 1, 2, 3) are connected to each base network NLm. The router Rm is a relay device that relays IP (Internet Protocol) packets between the network NW and the base network NLm. The base terminal Tm-l can reproduce the content distributed from the router Rm. The base terminal Tm-l at each base Pm is not limited to communicating with only the router Rm connected to the same base network NLm. For example, the viewing terminal T1-1 at the site P1 can communicate not only with the router R1 connected to the same site network NL1, but also with the router R2 at other sites P2, etc., a Web server, and the like. As shown in FIG. 1, in the content distribution system S, an overlay network ON is configured by a plurality of nodes Nn (n = 1, 2, 3,... K) that can communicate with each other via the network NW. Yes. The overlay network ON is a logical network that forms a virtual link. The overlay network ON is realized by a specific algorithm, for example, an algorithm using a distributed hash table. The distributed hash table is hereinafter referred to as “DHT (Distributed Hash Table)”. In the routing table using DHT, node IDs, IP addresses, and port numbers of a predetermined number of nodes Nn among all the nodes Nn participating in the overlay network ON are registered. Here, the node ID is unique identification information for identifying the node Nn from among the plurality of nodes Nn participating in the overlay network ON. The IP address is an example of location information indicating the location of the node Nn on the network NW. Further, to participate in the overlay network ON means to operate in a state where various messages can be transmitted to and received from other nodes Nn based on a routing table using DHT. As a result, each node Nn can transmit and receive messages to and from other nodes Nn via the overlay network ON. Here, transmission / reception of messages via the overlay network ON means transmission / reception of messages between the nodes Nn participating in the overlay network ON. Note that a routing table using DHT is well known in Japanese Patent Application Laid-Open No. 2006-197400 and the like, and thus detailed description thereof is omitted.

  In this embodiment, the node Nn participating in the overlay network ON includes a resident node and a general node. The resident node is an example of the “first information processing apparatus” in the present invention. The resident node is set as a device that contributes to the operation of the overlay network ON, for example. Here, “set” includes, for example, a case where it is arbitrarily set by a system administrator or the like and a case where the node Nn is set by determining whether or not the condition of the resident node is satisfied. . The resident node condition will be described later. On the other hand, the general node is an example of the “second information processing apparatus different from the first information processing apparatus” in the present invention. The router Rm regularly participates in the overlay network ON as a resident node. Here, “steady participation” means that, for example, when the resident node is not at the time of failure or maintenance, it participates without leaving the overlay network ON. In the present embodiment, the node Nn that regularly participates is, for example, the router Rm. In this case, a program for executing control processing as the node Nn is installed in the router Rm. In addition to each base Pm, a program that executes control processing as the node Nn may be installed in a device that is always connected to the network in each home. On the other hand, the user terminal UTo is a node device that does not always regularly participate in the overlay network ON as a general node. Here, the general node is a node device that participates in the overlay network ON for a predetermined time such as when the user uses the user terminal UTo, for example. Therefore, the general node repeats joining and leaving from the overlay network ON. That is, the general node joins or leaves the overlay network ON at an arbitrary timing. Even in the case of the user terminal UTo, the resident node condition may be satisfied. In this case, the user terminal UTo can participate in the overlay network ON as a resident node.

  In addition, various contents with different contents are distributed and stored in the plurality of nodes Nn participating in the overlay network ON. A content ID is assigned to the content stored in the node Nn. The content ID is unique identification information for identifying the content from among a plurality of contents stored in the node Nn when the overlay network is ON. Note that the node ID and the content ID are generated by, for example, a hash function common to the overlay network ON.

  Here, the node Nn that stores the content is hereinafter referred to as a “content holding node”. Information indicating the location of the content is stored as index information in the node Nn that manages the location of the content. The node Nn that manages the location of the content is hereinafter referred to as a “root node”. The index information includes a set of the node information of the content holding node storing the content and the content ID of the content. The node information includes, for example, the IP address, port number, and node ID of the content holding node. For example, the root node is determined to be the node Nn to which the node ID closest to the content ID is assigned. The node ID closest to the content ID is, for example, the node ID with the highest number of upper digits that match.

  A certain node Nn may acquire predetermined content from the content holding node via the overlay network ON. As an example of this case, there is a case where the node N1 that has received a request for a predetermined content from the base terminal T1-1 has not saved this content. In the example shown in FIG. 1, the node N1 is the router R1. In this case, the node N1 first performs a search process for searching for the location of the predetermined content stored in the content holding node in the overlay network ON. Here, the predetermined content is, for example, content selected as an acquisition target by the user of the base terminal T1-1. This predetermined content is hereinafter referred to as “content to be acquired”. The node N1 that performs the search process is hereinafter referred to as a “user node”. Specifically, the user node transmits a content location inquiry message to the root node by DHT routing in the search process. This content location inquiry message is a message for inquiring the location of the content to be acquired to the root node. The content location inquiry message includes the content ID of the content to be acquired. The DHT routing is known in, for example, Japanese Patent Application Laid-Open No. 2007-053662, and detailed description thereof is omitted.

  The root node that has received the content location inquiry message acquires index information corresponding to the content ID included in the content location inquiry message from the storage unit. Then, the root node returns a content location response message to the user node. This content location response message is a message for responding to the user node about the location of the content to be acquired. The content location response message includes the acquired index information and the like. Thus, when the user node receives the content location response message, it extracts index information from this message. The user node accesses the content holding node based on the IP address of the content holding node included in the extracted index information. Then, the user node returns a content request message to the content holding node. This content request message is a message for requesting the content holding node for the content to be acquired. This content request message includes the content ID of the content to be acquired.

  The content holding node that has received the content request message acquires content corresponding to the content ID included in the message from the storage unit. Then, the content holding node transmits the acquired content to the user node together with the content transmission message. The content acquired in this way is transmitted from the user node to the base terminal T1-1.

  Note that the root node may be configured to transmit a content transmission request message to the content holding node instead of transmitting the content location response message to the user node. This content transmission request message is a message for requesting transmission of the content to be acquired to the user node. The content transmission request message includes the content ID of the content to be acquired, the IP address of the user node, and the like. The content holding node that has received the content transmission request message acquires content corresponding to the content ID included in the message from the storage unit. The content holding node accesses the user node based on the IP address of the user node included in the content transmission request message. Then, the content holding node transmits the acquired content to the user node together with the content transmission message.

  When the user node stores the acquired content in the storage unit, the user node performs a publish process as a content holding node. This publishing process is a process for disclosing that the content is stored to other nodes Nn. In this publishing process, the content holding node transmits a publish message to the root node by DHT routing. This publish message includes the content ID of the content, node information of the content holding node, and the like. The root node that has received the publish message in this way stores a set of the content ID of the content included in the publish message and the node information of the content holding node as index information. The publishing process is performed at both the resident node and the general node. Therefore, in the index information provided from the root node of a certain content to the user node, the node information of the resident node and the node information of the general node are mixed.

  FIG. 2A is a diagram illustrating an example in which a publish message is transmitted from a content holding node to a root node by DHT routing. In the example shown in FIG. 2A, the content holding node acquires the IP address of the publish message transmission destination from the routing table using DHT. Similarly, the forwarding nodes X and Y also acquire the IP address of the transmission destination of the publish message from the routing table using DHT. Thus, as shown in FIG. 2A, the publish message transmitted from the content holding node is transferred by the two transfer nodes X and Y and reaches the root node. Here, the forwarding node refers to a node Nn that forwards a message. Similar to the root node, the forwarding node stores a set of the content ID included in the publish message and the node information of the content holding node. That is, the index information is also stored in the forwarding node existing on the publish message forwarding path. The forwarding node may receive a content location inquiry message transmitted from the user node to the root node. In this case, the forwarding node can transmit a content location response message including index information corresponding to the content to be acquired to the user node.

  In addition, the content holding node periodically transmits a publish message to the root node even after transmitting the publish message to the root node when the content is stored. This periodic publish message is hereinafter referred to as “periodic publish message”. FIG. 2B is a diagram illustrating an example in which a periodic publish message is transmitted from the content holding node to the root node by DHT routing. In the example shown in FIG. 2B, when the periodic publish message is transmitted, the forwarding node Y has already left the overlay network ON. Therefore, as shown in FIG. 2B, the forwarding node X forwards the periodic publish message to the new forwarding node Z. Note that the IP address of the forwarding node Z is acquired from a routing table using DHT. Thus, even if the message transfer path is changed, the index information can be stored in the transfer node existing on the transfer path after the change by the periodic publish message. Even when a new node Nn participates in the overlay network ON, the message transfer path can be changed.

  Further, the forwarding node periodically sends a route change confirmation message for confirming the change of the message forwarding route to the root node. The route change confirmation message includes the content ID in the index information stored in the forwarding node. FIG. 2C is a diagram illustrating an example in which a route change confirmation message is transmitted from the forwarding node X to the root node by DHT routing. In the example shown in FIG. 2C, when the route change confirmation message is transmitted, the forwarding node Y has already left the overlay network ON. Therefore, as illustrated in FIG. 2C, the forwarding node X forwards the route change confirmation message to the new forwarding node Z. Even when the message transfer path is changed in this way, the index information can be stored in the transfer node existing on the transfer path after the change by the path change confirmation message.

  By the way, the header of the message transmitted / received via the overlay network ON includes the node information of the node Nn that transmits this message and the node information of the node Nn that is the transmission destination of this message. The node Nn that has received the message updates the routing table using DHT based on the node information of the node Nn that has transmitted this message. Furthermore, in this embodiment, the message transmitted / received via the overlay network ON includes device identification information indicating that the node Nn that transmits this message is a resident node or a general node. Then, as will be described later, the node Nn receiving the message gives priority to the node information included in the message when the device identification information indicates the resident node based on the device identification information, and performs routing using DHT. Decide to register in the table. As a result, communication on the overlay network ON can be stabilized.

  Note that messages transmitted and received via the overlay network ON include various messages in addition to the content location inquiry message and the content request message described above. For example, there is a content deletion notification message. This content deletion notification message is a message for notifying the root node that the content has been deleted. The content deletion notification message is transmitted from the content holding node that has deleted the content to the root node of the content by DHT routing.

[ 2. Configuration and function of router Rm ]
Next, the configuration and function of the router Rm will be described with reference to FIG. FIG. 2D is a diagram illustrating a schematic configuration example of the router Rm. As shown in FIG. 2D, the router Rm includes a control unit 1, a storage unit 2, a communication unit 3a, a communication unit 3b, and the like. The control unit 1, the storage unit 2, the communication unit 3 a, and the communication unit 3 b are connected to each other via a bus 4. The memory | storage part 2 is an example of the memory | storage means in this invention. Each router Rm is assigned an IP address. The storage unit 2 is composed of, for example, a hard disk drive. The storage unit 2 stores an operating system, a node processing program, and the like. The node processing program or the like may be downloaded from a predetermined server connected to the network NW, for example. Alternatively, the node processing program or the like may be recorded on a recording medium and read via a drive of the recording medium, for example.

  In addition, the storage unit 2 stores a routing table or the like using DHT in the storage unit 2 of the router Rm that participates in the overlay network ON. Content is stored in a content storage area provided in the storage unit 2. The content storage area is a storage area for storing content.

  The communication unit 3a performs communication control with the user terminal UTo and the like through the network NW. The communication unit 3b performs communication control with the base terminal Tm-l through the base network NLm.

  The control unit 1 includes a CPU having a calculation function, a working RAM, a ROM, and the like. The control unit 1 is an example of the first to third receiving means, the first to third transmitting means, the first to fifth acquiring means, the determining means, the determining means, the second determining means, and the registering means in the present invention. The control unit 1 has a clock function and a timer function. With this timer function, a time determination timer, which will be described later, is set and counted. In addition, the control unit 1 operates as a resident node by executing a node processing program stored in the storage unit 2 or the like by the CPU. The control unit 1 has a function of relaying IP packets from other routers or hosts in the network layer, which is the third layer of the OSI (Open Systems Interconnection) reference model. Since the function of relaying IP packets is the same as that of a known router or L3 switching hub, detailed description thereof is omitted. Further, the control unit 1 has a function of distributing content requested from the base terminal Tm-l connected via the base network NLm to the base terminal Tm-l.

  The base terminal Tm-l may be configured to participate in the overlay network ON.

[ 3. Configuration and function of user terminal UTo ]
Next, the configuration and functions of the user terminal UTo will be described with reference to FIG. FIG. 2E is a block diagram illustrating a schematic configuration example of the user terminal UTo. As shown in FIG. 2E, the user terminal UTo includes a control unit 11, a storage unit 12, a buffer memory 13, a decoder unit 14, a video processing unit 15, a display unit 16, an audio processing unit 17, a speaker 18, and a communication unit. 19 and an input unit 19a and the like. The control unit 11, the storage unit 12, the buffer memory 13, the decoder unit 14, the video processing unit 15, the display unit 16, the audio processing unit 17, the communication unit 19, and the input unit 19a are connected to each other via a bus 19b. Yes. The storage unit 12 is an example of a storage unit in the present invention.

  The storage unit 12 is composed of, for example, a hard disk drive. The storage unit 2 stores an operating system, a node processing program, and the like. The node processing program or the like may be downloaded from a predetermined server connected to the network NW, for example. Alternatively, the node processing program or the like may be recorded on a recording medium and read via a drive of the recording medium, for example.

  Further, the storage unit 12 stores a routing table using DHT and the like in the storage unit 12 of the user terminal UTo that has participated in the overlay network ON. The content is stored in a content storage area provided in the storage unit 12.

  The buffer memory 13 buffers the received content. The decoder unit 14 performs decoding processing such as data expansion and decoding of video data and audio data included in the content. The video processing unit 15 performs a predetermined drawing process on the video data decoded by the decoder unit 14 and reproduces and outputs it as a video signal. The display unit 16 displays a video or the like on the display based on the video signal reproduced and output from the video processing unit 15. The display unit 16 displays the image decoded by the decoder unit 14. The audio processing unit 17 performs D (Digital) / A (Analog) conversion of the audio data decoded by the decoder unit 14 into an analog audio signal, and then amplifies this by an amplifier to reproduce and output. The speaker 18 outputs the audio signal reproduced and output from the audio processing unit 17 as a sound wave.

  The communication unit 19 performs communication control with the router Rm and the like through the network NW.

  The control unit 11 includes a CPU having a calculation function, a working RAM, a ROM, and the like. The control unit 11 is an example of the first to third receiving means, the first to third transmitting means, the first to fifth obtaining means, the determining means, the determining means, the second determining means, and the registering means according to the present invention. It is. The control unit 11 has a clock function and a timer function. With this timer function, a time determination timer, which will be described later, is set and counted. In addition, the control unit 11 operates as a resident node or a general node when the CPU executes a node processing program stored in the storage unit 12 or the like.

[4. Operation of Content Distribution System S]
Next, the operation of the content distribution system S will be described with reference to FIGS. FIG. 3A is a flowchart showing main processing in the node Nn. FIG. 3B is a flowchart showing details of the message transmission process in step S8 of FIG. FIGS. 4A and 5 are flowcharts showing details of the message reception process in step S10 of FIG. 3 to 5 are performed by the control unit 1 of the router Rm or the control unit 11 of the user terminal UTo that has joined the overlay network ON as the node Nn.

  The process shown in FIG. 3A is started when the node processing program is activated in the router Rm or the user terminal UTo. The activation of the node processing program is started, for example, when the router Rm or the user terminal UTo is turned on. Alternatively, the activation of the node processing program is started when the user terminal UTo issues a node processing program activation instruction via the input unit 19a.

  When the process shown in FIG. 3A is started, the node Nn determines whether or not the setting file is stored in the storage unit (step S1). This setting file stores device identification information indicating that the node Nn that is determined in step S1 is a resident node or a general node. And when it determines with the setting file being memorize | stored (step S1: YES), it progresses to step S2. In the case of the router Rm, for example, the setting file is stored when the router Rm is installed. In this setting file, device identification information indicating a resident node is stored.

  On the other hand, when it is determined that the setting file is not stored (step S1: NO), the process proceeds to step S3.

  In step S2, the node Nn reads the device identification information of the node Nn from the setting file into a predetermined storage area of the RAM, and proceeds to step S6. This predetermined storage area is an area for setting device identification information.

  On the other hand, in step S3, the node Nn determines whether or not the node Nn satisfies the resident node condition. The node Nn determines whether this node Nn is a resident node or a general node based on the determination result of step S3. Here, the condition of the resident node is set, for example, in the node processing program.

Examples of the resident node condition include the following (a) to (d).
(A) The duration of participation in the overlay network ON is a predetermined time or more (b) The storage capacity of the content storage area provided in the storage unit is a predetermined capacity or more (c) The communication unit is connected (D) It is possible to exceed NAT (Network Address Translation). Here, “the duration during which the overlay network has been ON” in (a) is: For example, it is stored in the storage unit when the node Nn leaves the overlay network ON last time. The stored duration time is referred to when the condition is determined. The “storage capacity of the content storage area” in (b) is referred to through the operating system at the time of condition determination, for example. Further, the “data communication speed of the communication line” in (c) is measured, for example, when the node Nn that performs the condition determination performs data communication with, for example, a predetermined resident node at the time of the condition determination. The “data communication speed of the communication line” in the above (c) is, in other words, “communication line bandwidth (bps)”. The “communication line bandwidth (bps)” may be obtained by counting the number of sessions with the communicating party. Further, whether or not the NAT can be exceeded in (d) is referred to through the operating system at the time of condition determination, for example. The NAT traversal technology includes a method in which a user appropriately sets port forwarding in a NAT-compatible router, and known methods such as “UPnP (Universal Plug and Play)” or “UDP (User Datagram Protocol) hole punching”. There is technology. However, in the Internet environment, even if NAT traversal is possible, connection from the Internet side may not be possible due to a personal computer personal firewall or the like. In consideration of the above, instead of the condition of (d) above, “from other devices connected to the network NW, TCP (Transmission Control Protocol) / IP (Internet Protocol) or UDP (User Datagram Protocol) / The condition may be that “IP connection can be accepted”. Here, “another device connected to the network NW” indicates, for example, another router Rm or another user terminal UTo connected to the network NW. The conditions (a) to (d) are conditions that can be regarded as a device that contributes to the operation of the overlay network ON. In addition to the above conditions (a) to (d), conditions that can be regarded as a device that contributes to the operation of the overlay network ON may be used.

  If it is determined that the condition of the resident node is satisfied (step S3: YES), the node Nn is determined to be a resident node, and the process proceeds to step S4. For example, when all the conditions (a) to (d) are satisfied, it is determined that the resident node condition is satisfied. Alternatively, if the condition (a) and one or more of the conditions (b) to (d) are satisfied, it is determined that the resident node condition is satisfied. Alternatively, when only the condition (a) is satisfied, it may be determined that the condition of the resident node is satisfied. On the other hand, if it is determined that the condition of the resident node is not satisfied (step S3: NO), the node Nn is determined to be a general node, and the process proceeds to step S5.

  In step S4, the node Nn stores device identification information indicating that it is a resident node in a predetermined storage area of the RAM. The node Nn creates a setting file for storing device identification information indicating that it is a resident node and stores it in the storage unit. Then, the process proceeds to step S6.

  On the other hand, in step S5, the node Nn stores device identification information indicating that it is a general node in a predetermined storage area of the RAM. Further, the node Nn creates a setting file for storing device identification information indicating that it is a general node and stores it in the storage unit. Then, the process proceeds to step S6.

  In step S6, the node Nn performs a participation process for participating in the overlay network ON. In this participation process, the node Nn transmits a participation message indicating a request to participate in the overlay network ON to a predetermined resident node. This resident node is a contact node that is first accessed by the node Nn participating in the overlay network ON. The IP address and port number of the content node are stored in the storage unit so as to be readable from the node processing program, for example. On the other hand, when the contact node receives the participation message, the contact node acquires a predetermined number of pieces of node information from the routing table using DHT. Here, the node information of the resident node is preferentially acquired from the routing table using DHT. Then, the contact node transmits the acquired predetermined number of pieces of node information to the node Nn that has transmitted the participation message. The contact node may be configured to transfer the participation message to another resident node registered in the routing table using DHT. In this case, the resident node that has received the transfer of the participation message acquires a predetermined number of pieces of node information from the routing table using DHT. Then, the resident node transmits the acquired predetermined number of pieces of node information to the node Nn that has transmitted the participation message. On the other hand, the node Nn that has transmitted the participation message receives a predetermined number of pieces of node information from a contact node or the like. Then, the node Nn generates a routing table using DHT that preferentially registers the node information of the resident node based on the received predetermined number of pieces of node information. “Registering node information of resident node preferentially” means, for example, deleting node information of a general node registered in the routing table using DHT, and replacing node information of resident node instead. Means to register. Alternatively, “preferentially registering node information of resident nodes” means, for example, registering more node information of resident nodes than node information of general nodes in a routing table using DHT. Alternatively, it is assumed that there are node information of a resident node and node information of a general node as candidates to be registered in a routing table using DHT. In this case, “preferentially register the node information of the resident node” means that the node information of the resident node is registered without registering the node information of the general node.

  Thus, the node Nn completes the participation in the overlay network ON by acquiring the routing table in which the node information of the resident node is preferentially registered. Then, the node Nn starts counting a time determination timer (not shown) by the timer function. This time determination timer is used to determine whether or not the duration time since joining the overlay network ON has become a predetermined time or more. Here, the predetermined time is set to 24 hours, for example. Further, the duration after participating in the overlay network ON is hereinafter referred to as “participation duration”. Note that the contact node may be configured to transmit the routing table itself using the DHT to the node Nn that transmitted the participation message, instead of transmitting a predetermined number of pieces of node information. In this case, the node Nn does not have to generate a routing table using DHT.

  Next, the node Nn determines whether or not to transmit a message (step S7). As described above, this message includes various types of messages such as a content location inquiry message, a content location response message, a content request message, a content transmission message, a publish message, and a route change confirmation message. The conditions for sending a message differ for each message type, but are well known and will not be described in detail. If the node Nn determines that a message is to be transmitted (step S7: YES), the process proceeds to step S8. On the other hand, when the node Nn determines not to transmit the message (step S7: NO), the process proceeds to step S9.

  In step S8, the node Nn performs message transmission processing. In this message transmission process, as shown in FIG. 3B, the node Nn acquires device identification information stored in a predetermined storage area (step S81). Next, the node Nn acquires the node information of the node Nn that is the transmission destination of the message (step S82). The node information of the node Nn that is a message transmission destination is acquired from, for example, a routing table using DHT or a message received immediately before. Next, the node Nn generates a message including the device identification information acquired in step S81 and the destination node information acquired in step S82 (step S83). Note that the generated message includes node information of the node Nn that transmits this message. Here, the node information of the node Nn that transmits the message is hereinafter referred to as “transmission side node information”. Furthermore, a content ID or the like may be included depending on the generated message. Then, the node Nn transmits the generated message to the node Nn that is the transmission destination of the message (step S84), and the process returns to the process illustrated in FIG. In this way, the device identification information is included in the transmitted message. Therefore, the node Nn that has received the message can quickly confirm whether the node Nn that has transmitted the message is a resident node or a general node.

  In step S9, the node Nn determines whether a message has been received. If the node Nn determines that the message has been received (step S9: YES), the process proceeds to step S10. On the other hand, when the node Nn determines that the message has not been received (step S9: NO), the process proceeds to step S11.

  In step S10, the node Nn performs message reception processing. Examples of this message reception process include the process shown in FIG. 4A and the process shown in FIG.

  First, the process shown in FIG. 4A will be described. The process shown in FIG. 4A is a process for registering only the node information of the resident node in the routing table using DHT. In the process shown in FIG. 4A, the node Nn performs a process according to the type of the received message (step S101). For example, it is assumed that the node Nn receives a content location inquiry message. In this case, the node Nn determines whether index information corresponding to the content ID included in the content location inquiry message is stored. If the node Nn stores the index information, the node Nn moves to step S8, transmits the index information to the user node that is the transmission source of the content location inquiry message, and returns to step S101.

  Next, the node Nn extracts device identification information and transmission side node information from the received message (step S102).

  Next, the node Nn determines whether or not a resident node is indicated in the device identification information based on the device identification information extracted in step S102 (step S103). That is, it is determined whether or not the node Nn that transmitted the message is a resident node. When the node Nn determines that the resident node is not indicated in the device identification information (step S103: NO), the node Nn returns to the process shown in FIG. That is, when the node Nn that transmitted the message is a general node, it is determined not to register the transmission side node information extracted in step S102 in the routing table using DHT. On the other hand, if the node Nn determines that the resident node is indicated in the device identification information (step S103: YES), the node Nn proceeds to step S104. In this case, whether or not the node information of the resident node is registered in the routing table using the DHT is determined in the processing after step S104.

  Here, an outline of a routing table using the DHT shown in FIG. 4B will be described. The routing table shown in FIG. 4B is an example of a routing table stored in the node Nn that has received the message. In the example shown in FIG. 4B, for convenience of explanation, the bit length of the node ID is 2 bits × 3 digits = 6 bits, and each digit is represented by a quaternary number. Further, it is assumed that the node ID of the node Nn that has received the message is “122”. The routing table using DHT shown in FIG. 4B is composed of level 1 to level 3 tables. Each level table has a registration area for registering node information for each area. This registration area is hereinafter referred to as “entry”. Among such a plurality of entries, an entry whose node ID is not registered is also included. Each area is an area obtained by dividing the ID space shown in FIG. For example, by dividing the ID space into four, a 0XX area, a 1XX area, a 2XX area, and a 3XX area are obtained. Here, “X” is an integer of 0 to 3. The level 1 table has entries corresponding to the 0XX area, 1XX area, 2XX area, and 3XX area, respectively. Further, by dividing the 1XX area including the node ID “122” into four, a 10X area, an 11X area, a 12X area, and a 13X area are obtained. The level 2 table has entries corresponding to the 10X area, the 11X area, the 12X area, and the 13X area. Further, by dividing the 12X area including the node ID “122” into four, 120 areas, 121 areas, 122 areas, and 123 areas are obtained. The level 3 table has entries corresponding to 120 areas, 121 areas, 122 areas, and 123 areas, respectively. When the bit length of the node ID is 16 digits × 4 bits, for example, a table for 16 levels is required.

  In step S104, the node Nn determines an entry capable of registering the node ID included in the transmission side node information extracted in step S102. Here, the entry capable of registering the node ID is an entry corresponding to the area including the node ID.

  In step S105, the node Nn determines whether or not the entry determined in step S104 is unregistered. For example, it is assumed that the node ID included in the transmission side node information is “112”. In this case, in the example shown in FIG. 4B, the entry E1 determined in step S104 is not registered. Alternatively, for example, it is assumed that the node ID included in the transmission side node information is “130”. In this case, in the example shown in FIG. 4B, the node ID “131” is already registered in the entry E2 determined in step S104. If the node Nn determines that the entry determined in step S104 is not registered (step S105: YES), the node Nn proceeds to step S106. On the other hand, when the node Nn determines that the entry determined in step S104 is not registered (step S105: NO), the node Nn proceeds to step S107.

  In step S106, the node Nn registers the transmission side node information extracted in step S102 in the entry determined in step S104, and returns to the process shown in FIG.

  On the other hand, in step S107, the node Nn determines whether the node ID included in the transmission side node information extracted in step S102 is the same as the node ID already registered in the entry determined in step S104. Determine. When the node Nn determines that the two node IDs are the same (step S107: YES), the process returns to the process shown in FIG. On the other hand, if the node Nn determines that the two node IDs are not the same (step S107: NO), the process proceeds to step S108.

  In step S108, the node Nn acquires information indicating the number of hops between the node Nn and the resident node corresponding to the transmission side node information extracted in step S102. The number of hops between the node Nn that has received the message and the resident node corresponding to the transmission-side node information extracted in step S102 is hereinafter referred to as “first hop number”. Further, the node Nn acquires information indicating the number of hops between the node Nn and another resident node already registered in the entry determined in step S104. The number of hops between the node Nn that has received the message and another resident node already registered in the entry determined in step S104 is hereinafter referred to as “second hop number”.

  Here, the hop count is the number of relay devices such as routers. The number of hops can be calculated by using TTL (Time To Live) set in the header of an IP packet transmitted / received between two nodes Nn. The value of the TTL set in the node Nn on the IP packet transmission side is decremented by 1 every time it passes through the relay device once. Therefore, the node Nn that has received the IP packet can acquire information indicating the number of hops by calculating the decrease number of the TTL value.

  Next, the node Nn determines whether or not the first hop number is smaller than the second hop number (step S109). This determination is performed in order to register the node information of the resident node with the smaller number of hops in the routing table using DHT.

  When the node Nn determines that the first hop number is not smaller than the second hop number (step S109: NO), the process returns to the process illustrated in FIG. That is, the registration of the node information of the resident node in the entry determined in step S104 is maintained. On the other hand, if the node Nn determines that the first hop number is smaller than the second hop number (step S109: YES), the node Nn proceeds to step S110.

  In steps S108 and S109, the number of hops between nodes Nn is used to determine node information to be registered in the routing table using DHT. As another example, the data communication speed of the node Nn may be used. In other words, the data communication speed is the bandwidth (bps) of the communication line between the nodes Nn. In this case, in step S108, the node Nn acquires information indicating the data communication speed between the node Nn and the resident node corresponding to the transmission side node information extracted in step S102. The data communication speed between the node Nn that has received the message and the resident node corresponding to the transmission side node information extracted in step S102 is hereinafter referred to as “first communication speed”. Further, the node Nn acquires information indicating the data communication speed between the node Nn and another resident node already registered in the entry determined in step S104. The data communication speed between the node Nn that has received the message and the other resident node already registered in the entry determined in step S104 is hereinafter referred to as “second communication speed”. Here, the data communication speed is measured by the node Nn performing data communication with each resident node. In step S109, the node Nn determines whether the first communication speed is faster than the second communication speed. This determination is performed in order to register the node information of the resident node with the higher data communication speed in the routing table using DHT. When the node Nn determines that the first communication speed is not faster than the second communication speed (step S109: NO), the process returns to the process illustrated in FIG. On the other hand, when the node Nn determines that the first communication speed is faster than the second communication speed (step S109: YES), the node Nn proceeds to step S110.

  Alternatively, as another example, the communication line band to which the communication unit of the node Nn is connected may be used. In this case, in step S108, the node Nn acquires information indicating the bandwidth of the communication line between the node Nn and the resident node corresponding to the transmission side node information extracted in step S102. The bandwidth of the communication line between the node Nn that has received the message and the resident node corresponding to the transmission side node information extracted in step S102 is hereinafter referred to as “first bandwidth”. The node Nn acquires information indicating the bandwidth of the communication line between the node Nn and another resident node already registered in the entry determined in step S104. The bandwidth of the communication line between the node Nn that has received the message and the other resident node already registered in the entry determined in step S104 is hereinafter referred to as “second bandwidth”. Here, the bandwidth is obtained by the node Nn measuring the data communication speed with each resident node. Alternatively, the bandwidth is obtained by obtaining the number of sessions of each resident node from each resident node. In step S109, the node Nn determines whether the first band is wider than the second band. This determination is performed in order to register the node information of the resident node with the wider bandwidth in the routing table using DHT. A wide band means that the data communication speed is high. In addition, a wide bandwidth means that the number of sessions is small. The large number of sessions of the resident node means that the number of communication partners with whom the resident node has a session is large. As a result, since the bandwidth is occupied by the number of sessions, the usable bandwidth is narrowed. Therefore, in step S109, the node Nn may compare and determine the number of sessions of both resident nodes. If the node Nn determines that the first band is not wider than the second band (step S109: NO), the process returns to the process illustrated in FIG. On the other hand, when the node Nn determines that the first band is wider than the second band (step S109: YES), the process proceeds to step S110.

  In step S110, the node Nn registers the transmitting side node information extracted in step S102 in place of the node information of the resident node registered in the entry determined in step S104, as shown in FIG. Return to processing. That is, in this case, the node information of the resident node that has transmitted the message is registered with priority over the node information of the resident node already registered in the entry. Thereby, the load given to the network NW can be reduced. Therefore, it is possible to update the node information of the node Nn, which is more appropriate as a message transmission destination, to be registered in the entry.

  As described above, according to the processing shown in FIG. 4A, the routing table using the DHT stored in each node Nn can be made a routing table in which only the node information of the resident node is registered. . Therefore, it is possible to avoid message delay caused by the node Nn registered in the routing table using DHT leaving. Therefore, communication in the overlay network ON can be stabilized.

  In the process shown in FIG. 4A, when “NO” is determined in step S107, the node Nn may be configured to proceed to step S110 without performing the processes in steps S108 to S109. That is, the node Nn may be configured to preferentially register the node information of the resident node without comparing the number of hops and the like. The same applies to steps S209, S210, S214, and S215 shown in FIG.

  Next, the process shown in FIG. 5 will be described. The process shown in FIG. 5 is a process of registering node information of a resident node and node information of a general node in a routing table using DHT. However, in the process shown in FIG. 5, the registration of the node information of the resident node has priority over the general node. Further, although not shown in the routing table using DHT shown in FIG. 4B, node information registered in each entry is registered in association with information indicating whether or not the node is a resident node. The Information indicating whether or not the node is a resident node is represented by a flag, for example. For example, when the flag is “1”, it indicates a resident node. On the other hand, when the flag is “0”, it indicates a general node.

  In the process shown in FIG. 5, the processes in steps S201, S202, S203, and 204 are the same as the processes in steps S101, S102, S104, and S105, respectively.

  If the node Nn determines that the entry determined in step S203 is not registered (step S204: YES), the node Nn proceeds to step S205. On the other hand, if the node Nn determines that the entry determined in step S203 is not registered (step S204: NO), the process proceeds to step S206.

  In step S205, the node Nn registers the transmission side node information extracted in step S202 and a flag indicating whether or not the node is a resident node in the entry determined in step S203, and performs the processing illustrated in FIG. Return to. Here, when the resident node is indicated in the device identification information extracted in step S202, a flag indicating that it is a resident node is registered in the entry.

  On the other hand, the process in step S206 is the same as the process in step S107. In step S206, when the node Nn determines that the node ID included in the transmission side node information extracted in step S202 is not the same as the node ID already registered in the entry determined in step S203. (Step S206: NO), the process proceeds to Step S207.

  The process in step S207 is the same as the process in step S103. When the node Nn determines that the resident node is indicated in the device identification information (step S207: YES), the node Nn proceeds to step S208. On the other hand, if the node Nn determines that the resident node is not indicated in the device identification information (step S207: NO), the process proceeds to step S213.

  In step S208, the node Nn determines whether the node information of the resident node is registered in the entry determined in step S203. For example, if the flag “1” is registered in this entry, it is determined that the node information of the resident node is registered. If the node Nn determines that the node information of the resident node is registered in the entry (step S208: YES), the node Nn proceeds to step S209. In this case, both the node Nn that transmitted the message and the node Nn that received the message are resident nodes. On the other hand, if the node Nn determines that the node information of the resident node is not registered in the entry (step S208: NO), the process proceeds to step S212.

  The process of steps S209 to S211 is the same as the process of S108 to S110.

  In step S212, the node Nn registers the transmission side node information extracted in step S202 in place of the node information of the general node registered in the entry determined in step S203. The process returns to A). That is, in this case, the node information of the resident node that transmitted the message is registered with priority over the node information of the general node already registered in the entry. In other words, the node information of the general node is deleted from the routing table using DHT. Therefore, as the number of resident nodes increases, a routing table using DHT in which a large amount of node information of resident nodes is registered can be obtained.

  Step S213 is the same as step S208. When the node Nn determines that the node information of the resident node is registered in the entry (step S213: YES), the node Nn returns to the process illustrated in FIG. That is, the registration of the node information of the resident node in the entry determined in step S203 is maintained. On the other hand, if the node Nn determines that the node information of the resident node is not registered in the entry (step S213: NO), the process proceeds to step S214. In this case, both the node Nn that transmitted the message and the node Nn that received the message are general nodes.

  Note that the processing in steps S214 to S216 is processing for registering node information of a general node having a smaller number of hops or a faster data communication speed in a routing table using DHT. The process of steps S214 to S216 is performed in the same manner as the process of S108 to S110.

  As described above, according to the processing shown in FIG. 5, the routing table using the DHT stored in each node Nn is made a routing table in which the node information of the resident node is registered with priority over the general node. Can do. Therefore, it is possible to reduce a message delay caused by the node Nn registered in the routing table using DHT leaving. Therefore, communication in the overlay network ON can be stabilized. In addition, according to the process shown in FIG. 5, unregistered entries in the routing table using the DHT stored in each node Nn can be reduced. Therefore, communication in the overlay network ON can be performed smoothly.

  Returning to the processing shown in FIG. 3A, in step S11, the node Nn determines whether or not the duration of participation in the overlay network ON has reached a predetermined time or more. For example, when the count value of the time determination timer becomes equal to or longer than a predetermined time, it is determined that the participation duration has become equal to or longer than the predetermined time. If the node Nn determines that the participation duration has become equal to or longer than the predetermined time (step S11: YES), the node Nn proceeds to step S12. In addition, when the participation continuation time becomes more than the predetermined time, the count value of the time determination timer is reset and the subsequent count is stopped. On the other hand, if the node Nn determines that the participation duration has not reached the predetermined time (step S11: NO), the node Nn proceeds to step S15.

  In step S12, the node Nn determines whether or not the resident node is indicated in the device identification information stored in the setting file stored in the storage unit of the node Nn. That is, it is determined whether or not the node Nn that performs this determination is set as a resident node. If the node Nn determines that the resident node is indicated in the device identification information (step S12: YES), the node Nn proceeds to step S15. On the other hand, if the node Nn determines that the resident node is not indicated in the device identification information (step S12: NO), the process proceeds to step S13. The case where it is determined that the resident node is not indicated in the device identification information is a case where the node Nn that performs this determination is set as a general node.

  In step S13, the node Nn determines whether or not the node Nn satisfies the resident node condition. The process in step S13 is basically the same as the process in step S3. However, in step S13, instead of the condition (a) in the case of step S3, the condition (a) is that the current participation duration is a predetermined time or more. If the node Nn determines that the resident node condition is satisfied (step S13: YES), the process proceeds to step S14. If only the condition (a) is used in step S13, this condition is determined in step S11. Therefore, in this case, the node Nn proceeds to step S14 without performing the determination in step S13. On the other hand, if the node Nn determines that the resident node condition is not satisfied (step S13: NO), the process proceeds to step S15.

  In step S14, the node Nn rewrites the device identification information stored in the predetermined storage area of the RAM from the general node to the resident node. In addition, the node Nn rewrites the device identification information stored in the setting file stored in the storage unit from the general node to the resident node. Thereby, the node Nn, which was a general node when participating in the overlay network ON, can be upgraded as a resident node thereafter. Thereafter, the device identification information in the message transmitted in the message transmission process in step S8 indicates that the node is a resident node.

  In step S15, the node Nn determines whether or not there is a process end instruction. For example, when there is a power-off instruction from the router Rm or the user terminal UTo, for example, it is determined that there has been a process end instruction. Alternatively, when there is an instruction to end the node processing program, it is determined that there is an instruction to end the process. If the node Nn determines that there is no processing end instruction (step S15: NO), the node Nn returns to step S7. On the other hand, if the node Nn determines that there is an instruction to end the process (step S15: YES), the process shown in FIG.

  As described above, according to the above-described embodiment, the node Nn that has received the message receives the device identification information based on the device identification information that is included in the message and indicates a resident node or a general node. It is determined that the node information included in the message when indicating the priority is registered in the routing table using DHT. As a result, only the node information of the resident node is registered in the routing table using DHT. Alternatively, in the routing table using DHT, the node information of the resident node is registered with priority over the node information of the general node. For this reason, it is possible to stabilize the communication on the overlay network ON in which the resident node and the general node are mixed. Therefore, the advantage that the resident node participates in the overlay network ON can be utilized.

  Further, as described above, since the node Nn registered in the routing table using DHT is less likely to leave the overlay network ON, the message transfer route is hardly changed. Therefore, the time interval for transmitting the periodic publish message and the route change confirmation message can be shortened compared to the conventional case. As a result, the load on the network NW can be reduced.

  Moreover, in the said embodiment, the frequency which a general node transfers a message becomes low by restrict | limiting the object registered into the routing table using DHT. However, similar to the resident node, the general node performs the publishing process. Therefore, the root node can provide the user node with index information in which node information of general nodes and resident nodes is mixed as a content holding node. As a result, the content storage area of the general node can be used effectively. In addition, the user node can efficiently perform distributed download of content by using index information in which node information of general nodes and resident nodes is mixed. Here, distributed download refers to downloading each piece of partial data constituting one content from different content holding nodes. Distributed download is an example of acquisition. A user node using index information in which node information of a general node and a resident node is mixed can use the general node and the resident node at a predetermined ratio. For example, 10 general nodes and 10 resident nodes can be used in half. Then, the user node downloads partial data from each of the general node and the resident node. Further, the speed at which the user node downloads partial data from the general node may be slower than a predetermined speed. In this case, if the user node is configured to switch the download destination from the general node to the resident node, the content can be downloaded more efficiently.

  In addition, after the index information including the node information of the general node is provided from the root node to the user node, the general node may leave the overlay network ON. In this case, the process in which the user node accesses the general node is wasted. Therefore, in the said embodiment, you may comprise so that a general node may not perform a publishing process. Thereby, the node information of the general node is not stored as index information in the root node or the like. Alternatively, the general node performs the publishing process, but the root node may be configured to discard the publish message from the general node. In this case, the root node does not store the node information of the general node as index information. Such a configuration is effective when there are many resident nodes and a content storage area for storing all the published contents can be secured only by the resident nodes.

  In the above embodiment, the router Rm or the user terminal UTo has been described as an example of the first information processing apparatus of the present invention. However, the present invention is not limited to this, and the first information processing apparatus is connected to the network NW. The server etc. connected to may be sufficient. Further, the first information processing apparatus may be basically a device such as a gateway that is regularly connected to the network NW.

  In the above embodiment, the peer-to-peer network using DHT is applied to the overlay network ON. However, the present invention is not limited to this. For example, a system using another overlay network may be applied. As a peer-to-peer system that does not use DHT, for example, there is a hybrid peer-to-peer system.

DESCRIPTION OF SYMBOLS 1,11 Control part 2,12 Storage part 3a, 3b, 19 Communication part 13 Buffer memory Rm Router UTo User terminal Nn Node NW Network ON Overlay network S Content delivery system

Claims (10)

In a communication system in which an overlay network is configured by a plurality of information processing apparatuses capable of communicating with each other via a network
The information processing device includes a first information processing device set as a device that contributes to the operation of the overlay network, and a second information processing device different from the first information processing device,
The information processing apparatus includes:
Storage means for storing a routing table for registering location information indicating the location of the information processing apparatus on the network;
A message transmitted from another information processing apparatus via the overlay network, wherein the location information of the other information processing apparatus and the other information processing apparatus are the first information processing apparatus or the second information processing apparatus. First receiving means for receiving the message including device identification information indicating that the information processing device is,
Based on the device identification information included in the received message, the location information included in the message when the device identification information indicates the first information processing device is prioritized and registered in the routing table. A communication means comprising: determining means for determining what to do. The information processing apparatus includes:
First transmitting means for transmitting a message to another information processing apparatus via the overlay network based on the location information registered in the routing table;
A determination unit that determines whether or not the information processing apparatus that transmits a message by the first transmission unit satisfies a condition of the set first information processing apparatus;
A second determination for determining whether the information processing apparatus transmitting the message by the first transmission means is the first information processing apparatus or the second information processing apparatus based on a determination result by the determination means; Means,
With
The first transmission means includes the location information of the information processing apparatus that transmits a message by the first transmission means, and the first information processing apparatus or the second information processing determined by the second determination means. Transmitting the message including the device identification information indicating that the device is a device to the other information processing device;
When the first information processing device is indicated in the device identification information included in the message, the determination unit determines to register the location information included in the message;
The information processing apparatus includes:
The communication system according to claim 1, further comprising registration means for registering the location information in the routing table when registration of the location information is determined by the determination means. The routing table has a plurality of registration areas for registering the location information,
The first information processing device is indicated in the device identification information included in the message, and the location information of the second information processing device is already registered in the registration area for registering the location information. 3. The information processing apparatus according to claim 2, wherein the determination unit determines to register the location information included in the message with priority over the location information registered in the registration area. The communication system described. Whether the information processing apparatus that transmits the message by the first transmission means has participated in the overlay network as a condition of the set first information processing apparatus for a predetermined time or more. Determine whether or not
When the determination unit determines that the second determination unit is equal to or longer than a predetermined time, the information processing apparatus that transmits a message by the first transmission unit is the first information processing apparatus. The communication system according to claim 2, wherein the communication system is determined. The determination unit is configured such that the information processing apparatus that transmits a message by the first transmission unit is configured as a condition of the set first information processing apparatus.
(1) The storage capacity of a storage area for storing content provided in the storage unit included in the information processing apparatus is greater than or equal to a predetermined capacity. (2) A communication line connected to the communication unit included in the information processing apparatus (3) Accepting a TCP (Transmission Control Protocol) / IP (Internet Protocol) or UDP (User Datagram Protocol) / IP connection from another device connected to the network To determine whether or not
The second determining unit transmits the message by the first transmitting unit when the determining unit determines that any one or more of the conditions (1) to (3) are satisfied. The communication system according to claim 2, wherein an apparatus determines that the apparatus is the first information processing apparatus.   The first information processing apparatus is a node apparatus that regularly participates in the overlay network, and the second information processing apparatus is a node apparatus that participates in or leaves the overlay network at an arbitrary timing. The communication system according to any one of claims 1 to 5, wherein: The information processing apparatus participating in the overlay network further includes a second transmission unit that transmits a participation message indicating a request to participate in the overlay network to the predetermined first information processing apparatus,
The first information processing apparatus includes:
Second receiving means for receiving a participation message transmitted from the information processing apparatus;
Fourth acquisition means for acquiring a predetermined number of the location information from a routing table for registering the location information of the predetermined number of the first information processing devices;
A third transmission means for transmitting the acquired predetermined number of the location information to the information processing apparatus that has transmitted the participation message;
With
The information processing apparatus participating in the overlay network is:
Third receiving means for receiving the predetermined number of the location information transmitted from the first information processing apparatus;
Based on the predetermined number of the location information received by the third receiving means, the routing table stored in the storage means, wherein the location information of the first information processing apparatus is preferentially registered. A fifth acquisition means for acquiring the routing table;
The communication system according to any one of claims 1 to 6, further comprising: In a communication system in which an overlay network is configured by a plurality of information processing apparatuses capable of communicating with each other via a network
The information processing device includes a first information processing device set as a device that contributes to the operation of the overlay network,
The information processing apparatus includes:
Storage means for storing a routing table for registering location information indicating the location of the information processing apparatus on the network;
A message transmitted from another information processing apparatus via the overlay network, wherein the location information of the other information processing apparatus and the other information processing apparatus are the first information processing apparatus or the first information processing apparatus. First receiving means for receiving the message including device identification information indicating that the second information processing device is different from the information processing device;
Based on the device identification information included in the received message, the location information included in the message when the device identification information indicates the first information processing device is prioritized and registered in the routing table. A determination means for determining what to do;
An information processing apparatus comprising: In a communication system in which an overlay network is configured by a plurality of information processing devices that can communicate with each other via a network,
The information processing device includes a first information processing device set as a device that contributes to the operation of the overlay network,
In a computer included in the information processing apparatus,
Storing a routing table for registering location information indicating the location of the information processing device on the network;
A message transmitted from another information processing apparatus via the overlay network, wherein the location information of the other information processing apparatus and the other information processing apparatus are the first information processing apparatus or the first information processing apparatus. Receiving the message including device identification information indicating that the second information processing device is different from the information processing device;
Based on the device identification information included in the received message, the location information included in the message when the device identification information indicates the first information processing device is prioritized and registered in the routing table. A step of deciding to do,
Information processing program to execute. A location information registration method in a communication system in which an overlay network is configured by a plurality of information processing devices that can communicate with each other via a network,
The information processing device includes a first information processing device set as a device that contributes to the operation of the overlay network,
The location information registration method is:
Storing a routing table for registering location information indicating the location of the information processing device on the network;
A message transmitted from another information processing apparatus via the overlay network, wherein the location information of the other information processing apparatus and the other information processing apparatus are the first information processing apparatus or the first information processing apparatus. Receiving the message including device identification information indicating that the second information processing device is different from the information processing device;
Based on the device identification information included in the received message, the location information included in the message when the device identification information indicates the first information processing device is prioritized and registered in the routing table. A step of deciding to do,
The location information registration method characterized by including.

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