JP4797679B2 - CONTENT DISTRIBUTION SYSTEM, CONTENT DATA MANAGEMENT DEVICE, ITS INFORMATION PROCESSING METHOD, AND ITS PROGRAM - Google Patents

Description

  The present invention belongs to the technical field of a content distribution system, a content data management device, an information processing method thereof, and a program thereof, and more specifically includes a plurality of node devices distributed on a network, and these node devices Belongs to a technical field of a content distribution system, a content data management device, an information processing method thereof, and a program thereof for transmitting / receiving content data between them.

  In recent years, so-called content distribution systems that distribute content data (hereinafter also referred to as “content”) such as music, movies, and talk programs via a network such as the Internet have been actively studied.

  As a basic configuration of the conventional content distribution system, there is a server client type distribution system. This server client type distribution system is configured to access a server that stores content from a terminal device that is a client and receive distribution of the content.

  However, in this type of distribution system, access from the terminal device is concentrated on a server device having specific popular content, and the desired content is made high-quality without stress in the terminal devices of a plurality of users who want to distribute the content. There is a disadvantage that it is difficult to obtain and view.

  In view of this, a technique has been proposed in which a distributed overlay table (DHT (Distributed Hash Table)) is used to logically construct an overlay network to efficiently distribute and distribute information to achieve load distribution.

  In this system, each node device that is a terminal device does not recognize link information (for example, IP address) to all the node devices participating in the overlay network. Only the link information to some of the obtained node devices is held, and content data search or the like is performed based on the link information.

In this overlay network, even when node devices are frequently joined and withdrawn (leaved), it is necessary to perform load distribution appropriately. Non-Patent Document 1 describes joining and leaving (leaved) in an overlay network. ), A technique for appropriately distributing the load even when it is frequently performed is disclosed.
"Examination of lightweight load distribution method for distributed hash table" The Institute of Electronics, Information and Communication Engineers IEICE Technical Report IN2003-189, February 2004

  In a peer-to-peer (P2P) type content distribution system that uses the technology of Non-Patent Document 1 in a content distribution system, each node device becomes a content distribution server that holds content data, and each node device requests a content distribution. Become a client.

  Also, in such a content distribution system, it is known that not only the node device which is a content distribution server holds content data but also other node devices on the network hold a copy of the content data. ing. Hereinafter, a node device that holds a copy of content data is also referred to as a replica holding node device. The node device that is a content distribution request client can also obtain the requested content from such a replica holding node device. Therefore, when a distribution request for a certain content increases, the content can be distributed not only from the node device that is the content distribution server, but also from the replica holding node device that holds a copy thereof, so that the node device that is the content distribution server It is possible to avoid concentration of access. Hereinafter, the content distribution server and the replica holding node device are collectively referred to as a content holding node device.

  As described above, in a peer-to-peer type content distribution system, for a certain content, a node device (hereinafter referred to as a “root node device”) that stores information on a plurality of content holding node devices that hold the content. The determined node device that requests the content (hereinafter referred to as “request node device”) is directed to the content node that has information regarding the content storage node device that stores the requested content. By transmitting request information (hereinafter referred to as “content search message”), information related to the content holding node device is acquired, and a content data distribution request is made to the content holding node device based on this information. Take.

  In such a content distribution system, when content is input, which node device stores content data is randomly determined by the content data management device which is a content input server. That is, the content data management device arranges the content holding node device on the content distribution system by transmitting and storing the content data to the randomly determined node device.

  The content holding node device that has received and stored the content data from the content data management device transmits a registration message including information about the stored content data and information about the own node device to the root node device based on the routing table. . The registration message is received by the root node device while being transferred by another node device.

  By the way, when information related to the content holding node device is stored only in the root node device, the number of times that the content search message is transferred from the request node device increases depending on the position of the request node device. It takes a long time to search for information. Further, a node device close to the root node device has an increased opportunity to receive a content search message.

  Therefore, the requesting node is obtained by causing the node device that transfers the registration message to hold the information about the content holding node device (the node device holding the information about the content holding node device is called “cache node device”). Information related to the content holding node device is returned in response to the content search message from the device.

  However, since the content holding node device is randomly determined by the content data management device as described above, the arrangement and number of cache node devices vary. For example, when the content holding node device is placed close to the root node device, the number of registration message transfers is reduced, and the number of cache node devices is reduced. As a result, the possibility that the content search message will reach the cache node device by the time it reaches the root node device from the request node device is reduced. Even if the cache node device is arranged, the time required for content search is sufficient. It cannot be reduced.

  The present invention has been made in view of the above disadvantages, and in a P2P type content distribution system having a plurality of node devices distributed and arranged on a network, a content distribution system capable of reducing content search time And providing a method and the like.

In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a plurality of node devices connected to each other via a network and a part of the plurality of node devices. A content data management device for storing the content data in the partial node device to be a content holding node device for storing content data to be shared between the devices, and the plurality of node devices include: Node identification information for identifying a plurality of node devices, wherein the node identification information composed of a predetermined number of digits is given, and the content data distributed in the content distribution system is composed of a predetermined number of digits. The content identification information for identifying the content data is given, and the container that holds the content data is stored. A root node device that stores location information indicating the location of the holding node device in the network is determined for each content data, and a difference between the content identification information of the content data held by the content holding node device is within a predetermined range The node device to which the node identification information is assigned is determined as the root node device, and is a message transmitted from the content holding node device to the root node device, and the content that has transmitted the message When at least one node device of the plurality of node devices receives the message including the location information of the holding node, the node device that has received the message sends the message to at least one node device of the plurality of node devices. as well as transfer, before the received A content distribution system for storing the location information included in a message, wherein the content data management device is a content data storage unit for storing the content data, and content for identifying the content data distributed in the content distribution system Content data identification information determining means for determining the content identification information comprising a predetermined number of digits, content data storage means for storing the content data, and content data stored in the content data storage means Content holding node device that holds the node identification information in which the first digit information is different from the content identification information of the content data to be held, or the largest exclusive OR Na Content holding node device determining means for determining, as the content holding node device, the node device having the node identification information or the node device having the node identification information having the largest numerical difference, and the content holding node device determining means Content holding request means for making a content data holding request to the content holding node apparatus determined by the receiving apparatus, wherein the node apparatus receives the holding request by the receiving means and the receiving means. Content data storage means for storing content data corresponding to the content data holding request, and the location information of the node device storing the content data when the content data is stored in the content data storage means. Registration message containing A registration message transmitting means for transmitting to said root node device destined for the stored the contents data, characterized by having a.

According to a second aspect of the present invention, a plurality of node devices connected to each other via a network and a part of the plurality of node devices are shared between the plurality of node devices. A content data management device for storing the content data in the part of the node devices, so that the plurality of node devices identify the plurality of node devices. Node identification information that is configured to have a predetermined number of digits and is provided with the node identification information, and the content data distributed in the content distribution system is configured with a predetermined number of digits to identify the content data. The content holding node device that is provided with content identification information and holds the content data The node in which a root node device that stores location information indicating a location in a network is determined for each content data, and the difference between the content identification information of the content data held by the content holding node device is within a predetermined range A node device to which identification information is assigned is determined to be the root node device, and is a message transmitted from the content holding node device to the root node device, and the location of the content holding node that has transmitted the message When at least one node device of the plurality of node devices receives a message including information, the node device that has received the message transfers the message to at least one node device of the plurality of node devices , and Before the received message contains And have you in the content distribution system that stores the location information, the content data management apparatus, a content identification information identifying the content data distributed in the content distribution system, the content identification consists predetermined number of digits Content data identification information determining means for determining information, content data storage means for storing the content data, and a content holding node device for holding the content data stored in the content data storage means, the content data being held The node device having the node identification information in which the first digit information is different from the content identification information, the node device having the node identification information having the largest exclusive OR, or the numerical difference is the most. No to grow Content holding node device determining means for determining a node device having node identification information as the content holding node device, and a content holding request for making a content data holding request to the content holding node device determined by the content holding node device determining means And means.

Further, in the invention described in claim 3, in the invention described in claim 2 , the content holding node device determining unit is configured to identify information whose first digit is different from the identification information of the content data to be held. When determining a plurality of content holding node devices when determining a node device having information as the content holding node device, the content data holding node device is a node device having different identification information in the upper first digit. It is determined as follows.

According to a fourth aspect of the present invention, in the invention according to the third aspect, the content holding node device determining means is configured such that the number of the content holding node devices to be determined is equal to or greater than the number of the upper first digit. In this case, the content holding node device having a number equal to or higher than the number of the upper first digit is randomly determined.

According to a fifth aspect of the present invention, a plurality of node devices connected to each other via a network and a part of the plurality of node devices are shared between the plurality of node devices. A content data management device for storing the content data in the part of the node devices, so that the plurality of node devices identify the plurality of node devices. Node identification information that is configured to have a predetermined number of digits and is provided with the node identification information, and the content data distributed in the content distribution system is configured with a predetermined number of digits to identify the content data. The content holding node device that is provided with content identification information and holds the content data The node in which a root node device that stores location information indicating a location in a network is determined for each content data, and the difference between the content identification information of the content data held by the content holding node device is within a predetermined range A node device to which identification information is assigned is determined to be the root node device, and is a message transmitted from the content holding node device to the root node device, and the location of the content holding node that has transmitted the message When at least one node device of the plurality of node devices receives a message including information, the node device that has received the message transfers the message to at least one node device of the plurality of node devices , and Before the received message contains And have you in the content distribution system that stores the location information, the contents data management apparatus, a content identification information identifying the content data distributed in the content distribution system, the content identification consists predetermined number of digits A content data identification information determining step for determining information; and a content holding node device for holding the content data stored in the content data storage means for storing the content data, wherein the content identification information of the content data to be held is A node device having the node identification information having different first digit information, a node device having the node identification information having the largest exclusive OR, or the node identification information having the largest numerical difference. Node device having A content holding node device determination step for determining the content holding node device as a content holding node device, and a content holding request step for making a content data holding request to the content holding node device determined by the content holding node device determination step. It is a program.

According to a sixth aspect of the present invention, a plurality of node devices connected to each other via a network and a part of the plurality of node devices are shared between the plurality of node devices. A content data management device for storing the content data in the part of the node devices, so that the plurality of node devices identify the plurality of node devices. Node identification information that is configured to have a predetermined number of digits and is provided with the node identification information, and the content data distributed in the content distribution system is configured with a predetermined number of digits to identify the content data. The content holding node device that is provided with content identification information and holds the content data The node in which a root node device that stores location information indicating a location in a network is determined for each content data, and the difference between the content identification information of the content data held by the content holding node device is within a predetermined range A node device to which identification information is assigned is determined to be the root node device, and is a message transmitted from the content holding node device to the root node device, and the location of the content holding node that has transmitted the message When at least one node device of the plurality of node devices receives a message including information, the node device that has received the message transfers the message to at least one node device of the plurality of node devices , and Before the received message contains An information processing method in a content distribution system for storing location information, wherein the content data management device is content identification information for identifying the content data distributed in the content distribution system, and comprises a predetermined number of digits. A content data identification information determining step for determining the content identification information, and a content holding node device for holding the content data stored in the content data storage means for storing the content data, wherein the content of the content data to be held The node device having the node identification information whose upper first digit information is different from the identification information, the node device having the node identification information having the largest exclusive OR, or the numerical difference being the largest Node identification information A content holding node device determination step for determining a node device having information as the content holding node device, a content holding request step for making a content data holding request to the content holding node device determined by the content holding node device determination step, And the node device receives the holding request, and the content data storing step stores the content data corresponding to the holding request for the content data when the holding unit receives the holding request. When the content data is stored in the content data storage means, a registration message including the location information of the node device storing the content data is transmitted to the root node device of the stored content data. And having a message transmission step.

According to the first , second, fifth , and sixth aspects of the present invention, the content data management device sets the identification information of the content holding node device that holds the content data to the first digit of the content data identification information. The identification information with different eye information, the identification information with the largest exclusive OR, or the identification information with the largest numerical difference is determined, and the content data is requested to be retained using the determined identification information as the destination identification information. Therefore, the number of times that the registration message transmitted from the content holding node device is transferred increases, and a large number of cache node devices are arranged. As a result, the content search message from the request node device that searches for content is more likely to reach the cache node device before reaching the root node device, so that the time required for content search is reduced overall. . In addition, a node device close to the root node device has a reduced chance of transferring a content search message for searching for content. Therefore, the load on the node device close to the root node device can be reduced.

In addition, when determining a node device having identification information in which the first digit information is different from the content data identification information to be held as a content data holding node device, for example, in a Pastry type or tapestry type content distribution system The number of registration message transfers can be increased as much as possible. Therefore, since the number of times that the registration message transmitted from the content holding node device is transferred increases, the time required for content search can be reduced overall, and the load on the node device close to the root node device can be reduced. Can be reduced. Alternatively, in the case of determining a node device having identification information having the largest exclusive OR with respect to the content data identification information to be held as a content data holding node device, for example, a kedemulia type content distribution system The number of registration message transfers can be increased as much as possible. Therefore, since the number of times that the registration message transmitted from the content holding node device is transferred increases, the time required for content search can be reduced overall, and the load on the node device close to the root node device can be reduced. Can be reduced. Alternatively, in the case of determining a node device having identification information with the largest numerical difference as content data holding node device with respect to the identification information of the content data to be held, for example, registration in a chord type content distribution system The number of message transfers can be increased as much as possible. Therefore, since the number of times that the registration message transmitted from the content holding node device is transferred increases, the time required for content search can be reduced overall, and the load on the node device close to the root node device can be reduced. Can be reduced

According to the third aspect of the present invention, when a plurality of content holding node devices are determined, node devices having different identification information in the first first digit are determined as content data holding node devices. Even when the management device arranges a plurality of content holding node devices, the number of registration message transfers can be increased as much as possible. Accordingly, since the number of times the registration message transmitted from the content holding node device is transferred increases, the time required for content search can be reduced overall, and the load on the node device close to the root node device can be reduced. Can be reduced.

According to the fourth aspect of the present invention, when the number of content holding node devices to be determined is equal to or greater than the number of the first digit, content holding node devices greater than the number of the upper first digit are randomly determined. Therefore, even when a large number of content holding node devices are arranged in the content distribution system, the calculation load of the content data management device can be reduced.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best embodiment of the invention will be described with reference to the drawings. The embodiment described below is an embodiment in the case where the information to be distributed is content data such as music data or video data, and the present invention is applied to a pastry type or tapestry type content distribution system.

[1. Content distribution system configuration]
First, a schematic configuration and the like of a content distribution system as an information distribution system will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of a connection mode of each node device that is a terminal device in the content distribution system according to the present embodiment. This content distribution system is composed of a plurality of node devices distributed on a network, and transmits and receives content data between the node devices.

  As shown in the lower frame 101 of FIG. 1, IX (Internet eXchange) 3, ISP (Internet Service Provider) 4, DSL (Digital Subscriber Line) line operator (device) 5, FTTH (Fiber To The Home) line A network (real-world network) 8 such as the Internet is constructed by an operator (device) 6 and a communication line (for example, a telephone line or an optical cable) 7.

  As shown in the upper frame 100 of FIG. 1, the content distribution system S includes a plurality of node devices 1a, 1b, 1c... 1x, 1y as terminal devices of the present invention connected to each other via a network 8. , 1z... And a peer-to-peer (P2P) network system. Each node device 1a, 1b, 1c... 1x, 1y, 1z... Is assigned a unique manufacturing number (for example, a MAC address) and an IP (Internet Protocol) address as information indicating the node device. . Note that the serial number and IP address are not duplicated among the plurality of node devices 1. In the following description, when any one of the node devices 1a, 1b, 1c... 1x, 1y, 1z.

[1.1. Outline of DHT]
The algorithm using the distributed hash table (hereinafter referred to as “DHT” (Distributed Hash Table)) according to the present embodiment will be described below.

  In the content distribution system S described above, when the node devices 1 exchange information with each other, they must know IP addresses as location information of each other.

  For example, in a system for sharing content with each other, it is a simple technique for each node device 1 participating in the network 8 to know the IP addresses of all the node devices 1 participating in the network 8. However, when the number of terminals becomes as large as tens of thousands and hundreds of thousands, it is not realistic to remember the IP addresses of all the node devices 1. Also, if the power supply of an arbitrary node device is frequently turned on or off, the IP address of the arbitrary node device stored in each node device 1 is frequently updated, which makes operation difficult.

  Therefore, one node device 1 stores only the minimum necessary IP addresses of some of the node devices 1 participating in the network 8, and stores the IP address. For node devices 1 that are not connected, a system has been devised to deliver content by transferring information between the node devices 1.

  As an example of such a system, an overlay network 9 as shown in the upper frame 100 of FIG. 1 is constructed by an algorithm using DHT. That is, the overlay network 9 means a network that forms a virtual link formed by using the existing network 8.

  In this embodiment, it is assumed that the overlay network 9 is constructed by an algorithm using DHT, and the node device 1 arranged on the overlay network 9 participates in the content distribution system S (in other words, the overlay network 9). The node device 1 participating in the network. Participation in the content distribution system S is performed when a node device that has not yet participated sends a participation request to an arbitrary node device 1 that has already participated.

As a node ID that is an identification number of each node device 1 participating in the content distribution system S, a unique number (unique number) is assigned to each node device 1. This number must have a number of bits sufficient to accommodate the maximum number of node devices. For example, if a ¹²⁸ -bit number is used, 2 ¹²⁸ = 340 × 10 ³⁶ node devices can be operated.

  More specifically, the node ID of each node device 1 is obtained by hashing a unique value for each node device 1 such as the IP address or manufacturing number of each node device 1 with a common hash function (hash algorithm). The obtained hash value is distributed and arranged in one ID space without deviation. Thus, the node ID obtained by hashing with a common hash function has a very low probability of having the same value if the IP address or the manufacturing number is different. Since the hash function is publicly known, detailed description thereof is omitted. In the present embodiment, a node ID is a value obtained by hashing an IP address (global IP address) with a common hash function.

  Further, content data (for example, music data, movie data, document data) as shared information distributed from one node device 1 to another node device 1 is sent to a plurality of node devices 1 participating in the content distribution system S. Data, etc.) are stored in a distributed manner, and a unique identification number (hereinafter referred to as “content ID”) for each content data is also given to the content data.

  Then, the content ID has the same length as the node ID (for example, 128 bits), and the content data management device 10 which will be described in detail later calculates a random value using a pseudo random number algorithm or a random number generation circuit. The value calculated at random is determined by hashing with a hash function common to the node ID obtained (that is, arranged in the same ID space as the hash value of the IP address of the node device 1). Then, the node device 1 having the node ID closest to the hash value (for example, the higher-order digits match more) is referred to as a node device 1 that holds content data (hereinafter referred to as “content holding node device”). Link information, that is, identification information (node ID or IP address) of the content holding node device is held.

  As described above, since the node ID and the content ID assigned to each node device 1 and each content data are generated by a common hash function, as shown in FIG. Can be thought of as being scattered and present. This figure shows a node ID and content ID assigned in 32 bits. In the figure, a round dot indicates a node ID, a square indicates a content ID, and the ID increases counterclockwise.

  Next, which content data is managed by which node device 1 is determined under a certain rule. In the present embodiment, the rule is that “a node device 1 that manages content data having a certain content ID is a node device 1 having a node ID close to that content ID”. Here, the definition of “close” does not exceed the content ID, and the difference between the content ID and the node ID is the smallest. In practice, each content data is managed by each node device 1. Other definitions may be used as long as they are consistent. In the example shown in FIG. 2, based on this definition, the content IDa is managed by the node device 1 having a node ID close to the content IDa (hereinafter referred to as “node IDa”), and the content IDb is the content IDb. Managed by the node device 1 having a node ID close to IDb (hereinafter referred to as “node IDb”), and the content IDc has a node ID close to the content IDc (hereinafter referred to as “node IDc”). Managed by the device 1.

  Here, “management” does not mean that content data is held, but means “knows which node device 1 holds content data”. That is, in FIG. 2, the node device 1 having the node IDa knows which node device 1 holds the content data having the content IDa, and the node device 1 having the node IDb and the node having the node IDc Similarly, the device 1 knows which node device 1 holds the content data having the content IDb and the content data having the content IDc. Thus, the node device 1 that knows which node device 1 holds certain content data is called the root node device of the content data. That is, the node device 1 having the node IDa is the root node device of the content data having the content IDa, and the node device 1 having the node IDb is the root node device of the content data having the content IDb, and the node IDc Is a root node device for content data having content IDc.

  Further, the content data management device 10 has a function of distributing content data so that the node device in the content distribution system S is a content holding node device, and a function of generating a catalog list and providing it to the node device. Yes.

[1.2. Create routing table]
Here, an example of a method for creating a routing table used in DHT will be described with reference to FIG. FIG. 3 is a diagram illustrating an example of how a routing table is created by DHT.

  First, as shown in FIG. 3A, the ID space is divided into several areas. Actually, about 16 divisions are often used, but in order to simplify the explanation, four divisions are used here, and the ID is represented by a quaternary number having a bit length of 8 bits. An example in which the node ID of the node device 1N is “1133” and the routing table of the node device 1N is created will be described.

(Level 1 routing)
First, when the ID space is divided into four areas, each area is represented by four areas “0XXX”, “1XXX”, “2XXX”, “3XXX” (X is a natural number from 0 to 3, The same shall apply hereinafter.) Since the node ID of the node device 1N itself is “1133”, the node device 1N exists in the lower left “1XXX” area in FIG. Then, the node device 1N determines from the information transmitted from the node device 1 that has received the participation request, the area other than the area where the node device 1 exists (that is, the “1XXX” area) (that is, the “0XXX” area, “ The node device 1 existing in the “2XXX” area and the “3XXX” area) is selected, and the node ID and IP address of the node device are stored in the level 1 table.
FIG. 4 is an example of a level 1 table. In this table, “0100” is selected as the node ID of the “0XXX” area, “2133” is selected as the node ID of the “2XXX” area, and “3213” is selected as the node ID of the “3XXX” area. Show. Since the second column of level 1 indicates the node device 1N itself, it is not necessary to store the IP address.

(Level 2 routing)
Next, as shown in FIG. 3B, among the areas divided into four by the above routing, the area “11xx” where the user exists is further divided into four, and further four areas “10XX”, “11XX”, “12XX” ”And“ 13XX ”. Then, similarly to the above, the node device 1 existing in an area other than the area “11xx” in which it exists is appropriately selected, and the node ID and IP address of the node device are stored in the level 2 table. FIG. 4 is an example of a level 2 table. In this table, “1003” is selected as the node ID of the “10XX” area, “1221” is selected as the node ID of the “12XX” area, and “1313” is selected as the node ID of the “13XX” area. Is shown. The second column of level 2 is an area “11XX” in which the node device 1N exists, and since it is tabulated at level 3 to be described later, no IP address is stored. If no node device exists in the area, the node ID and IP address fields are blank.

(Level 3 routing)
Further, among the areas divided into four by the routing, the area “113X” in which the user exists is further divided into four, and further divided into four areas “110X”, “111X”, “112X”, and “113X”. Then, similarly to the above, the node device 1 existing in an area other than the area “113X” in which it is present is appropriately selected, and the node ID and IP address of the node device are stored in the level 3 table. FIG. 4 is an example of a level 3 table. The fourth column of level 3 is an area where the node device 1N exists, and since it is tabulated at level 4 described later, no IP address is stored. If no node device exists in the area, the node ID and IP address fields are blank.

  In this way, all the 8-bit IDs can be covered by creating a routing table as shown in FIG. As the level goes up, white space becomes more noticeable in the table.

  All the node devices 1 each create and own the routing table created according to the method described above. As described above, each node device 1 has a routing table in which node IDs and IP addresses that are identification information of some of the node devices 1 in the content distribution system S are associated.

[1.3. Content data search method]
Next, an example of a search method for the node device 1 that holds content data will be described with reference to FIG. FIG. 5 is a diagram illustrating an example of a state in which the node device 1 holding content data is searched by DHT.

  Here, a procedure when the node device 1N having the node ID “1133” searches for content data having the content ID “3020” will be described. Hereinafter, a node device that searches for content data and requests reception of content data in this way is referred to as a “request node device”.

  The request node device 1N refers to the routing table held by itself, and uses the node ID of the node device having the node ID in the same area as the content ID “3020” as the destination identification information. A transmission request (hereinafter referred to as “content search message”) is transmitted. If the request node device 1N has the routing table having the same value as that in the example of FIG. 4, the content ID “3020” is the “3XXX” area, and therefore the node device 1 belonging to the “3XXX” area. The content search message is transmitted to the node device 1A (node ID “3213”) that knows the IP address (that is, the IP address is stored in the routing table held by itself). Thus, the content search message includes a content ID that is unique identification information corresponding to the content, and this content ID is used as destination identification information in the content search message.

  According to the example shown in FIG. 5, since the IP address of the node device 1A having the node ID “3213” is stored in the routing table (see FIG. 4) of the request node device 1N, the request node device 1N A content search message is transmitted to the node device 1A whose node ID is “3213”.

  Next, the node device 1A that has received the content search message determines whether or not the content search message is a message addressed to its own node device 1A. Whether the message is addressed to the own node device 1A is determined based on the destination identification information and the routing table. Specifically, it is determined whether or not the destination identification information is close to the node ID that is identification information of the own node device 1A. That is, for the destination identification information, the node ID of the closest node device from the node ID of the node device stored in the routing table (the table value is not shown) held by the node device 1A itself is It is determined whether it is itself or another node device. Since the node ID of the other node device is closer to the destination identification information than the node ID of the own node device 1A, the node device 1A has the level 2 of the routing table held by the node device 1A itself. With reference to the table, the content search message is transferred to the node device 1B (node ID “3031”) that knows the IP address among the node devices 1 belonging to the area “30XX”.

  As described above, when the transfer of the content search message proceeds in the manner of adapting the digits of the content ID in order from the top and finally reaches the node device 1C that manages the content data, that is, the root node device, the route The node device searches the content ID “3020” included in the content search message from index information (described later) managed by itself, and information (node ID) regarding the content holding node device that owns the content data. Or the IP address) is returned to the request node apparatus 1N. A mechanism for transferring a message such as a content search message to the target node device as described above is called DHT routing.

  In this way, the request node device 1N receives and knows information about the content holding node device holding the content data with the content ID “3020” from the root node device 1C, and the content holding node device receives the content. Data will be downloaded and acquired.

[1.4. How to register in the index table]
In the content distribution system S having such a configuration, for example, a method when a certain node device 1 publishes new content data so that it can be searched from other node devices 1 on the content distribution system S will be described. . This node device 1 is a content holding node device that stores and holds content data.

  The content holding node device that stores the content data distributed from the content data management device 10 is directed to the node device having the same node ID as the content ID of the stored content data (whether or not this node device actually exists). Not sure at the moment.) Send a registration message. And this registration message is also transferred one after another according to the routing table in the same manner as the content search message, and when it is transferred to the node device 1 having the node ID closest to the content ID included in the registration message, If the node device 1 determines that there is no other node device 1 as the transfer destination, the node device 1 determines that the node device 1 itself should be the root node device of the content, and the content ID and content included in the registration message. The node ID and IP address of the holding node (hereinafter referred to as “index information”) are stored as index information.

  Furthermore, in the present embodiment, the node device 1 in the middle of the path through which the registration message is transferred to the root node device is configured to hold the index information included in the registration message as a cache. The device is called a cache node device. As a result, the cache node device receives the IP address or node ID of the content holding node device when the content search message is transferred to the cache node device before the root node device receives the content search message for searching for content. Can be returned to the request node device that has searched for the location of the content. In the present embodiment, at least the IP address of the content holding node device is returned in response to the content search message, but the node ID may be returned together with the IP address of the content holding node device.

  When transferring a registration message, the cache node device normally holds index information based on the registration message as described above.

  Here, as shown in FIG. 6A, the node device 1M having the node ID “1301” is set as the content holding node device holding the content having the content ID “3020”, and the node ID is “3011”. Retention of index information when the node device 1C is the root node device of the content with the content ID “3020” will be described with reference to FIGS. 6 (a) and 6 (b).

  As shown in FIGS. 6A and 6B, when the node apparatus 1M, which is a content holding node apparatus, transmits a registration message including index information, the node apparatus 1A that has received the message holds the index information. Therefore, it functions as a cache node device (1). The cache node device (1) transfers the registration message. The node device 1B that has received the registration message functions as a cache node device (2) by holding the index information. The cache node device (2) transfers the registration message. The node device 1C that has received the registration message functions as a root node device by holding the index information. In this way, the node devices 1A, 1B, and 1C hold the index information included in the registration message.

  By the way, holding of index information in the root node device and the cache node device is performed by an index table as shown in FIG. FIG. 7 shows an example of an index table in the root node device 1C, which stores the node ID, IP address, etc. of the content holding node device related to the content with the content ID “3020” that is managed by the node device As the cache node device, the identification information of the content holding node device relating to the content with the content ID “2021” is stored. In addition to the content ID, the node ID of the content holding node device, and the IP address, the index table can also store copyright information and the like.

[1.5. Arrangement method of content holding node device]
Here, the arrangement method of the content holding node device in the content data management device as the content input server will be specifically described with reference to the drawings. FIG. 8 is a diagram showing an example in which content holding node devices are randomly arranged. FIG. 9 and FIG. 10 show content holding node devices that can reduce the content search time. It is a figure which shows the example at the time of arrange | positioning a holding | maintenance node apparatus.

  In the conventional content data management device, since the content holding node device is randomly arranged, the content holding node device may be arranged in an ID space near the root node device. For example, as shown in FIG. 8 (a), the content data management device is a node device 1F, 1G in the ID space whose uppermost digit is the same as the node ID of the root node device 1E that manages the content with the content ID “1231”. The content holding node device may be selected. When the content holding node device is thus selected, the content data management device distributes the content data to the node devices 1F and 1G. The node devices 1F and 1G that have become content holding node devices transmit a registration message to the root node device 1E. In FIG. 8A, the content holding node device 1F has an IP address corresponding to the node ID of the root node device 1E in the routing table of its own node device, and therefore registration from the content holding node device 1F. The message is transmitted directly to the root node device 1E. On the other hand, the content holding node device 1G transmits a registration message to the node device 1H according to the routing table of the own node device. When the node device 1H receives the registration message, the node device 1H acquires the index information included in the registration message and becomes a cache node device of the content “1231”. Further, the node device 1H has an IP address corresponding to the node ID of the root node device 1E in the routing table of its own node device, and transfers the registration message transmitted from the content holding node device 1G to the root node device 1E. To do.

  FIG. 8B is a simplified representation of the path through which the content search message is transferred in FIG. 8A in a tree structure. As shown in FIG. 8B, the cache node device 1H and the content holding node devices 1F and 1G are concentrated and arranged near the root node device 1E. Therefore, for example, when the node device 1J functions as a request node device, it takes time to reach the cache node device 1H, and even if the cache node device 1H is arranged, it takes time to search for content. Cannot be reduced sufficiently.

  Therefore, in the content data management apparatus 10 according to the present embodiment, when content data is distributed and the content holding node apparatus to be held is determined, the node ID that is the identification information of the content holding node apparatus and the identification information of the content data are used. A node device having a node ID having a predetermined relationship with a certain content ID is determined as a content data holding device.

  For example, as shown in FIG. 9A, the content data management apparatus 10 has a node ID “ID having a highest ID digit different from the content with the content ID“ 1231 ”(hereinafter referred to as“ content “1231”). The node device 1K having “2xxx” (x is an arbitrary value from 0 to 3) is selected and determined as the content holding node device. Note that there is no node device at “1xxx” and there is no node device at “1xxx” that should be the root node device with the content ID “1231”. The node ID “0xxx” may be the root node device. Originally, the root node device and the content holding node device are to be selected so that they exist in different areas. However, since it is not always possible, the node device determined as the content holding node device has the content ID. It is desirable to use a node device in an area where there is a low possibility that a node device serving as the root node device of “1231” exists. Here, since the root node device is the node device having the node ID closest to the content ID, the area where the node device that is the root node device with the content ID “1231” is unlikely to exist is “2xxx”. Become. When the node device 1K is determined as the content holding node device in this way, the content data management device 10 distributes the data of the content “1231” to the node device 1K. The node device 1K that has become the content holding node device transmits a registration message to the root node device 1E. In FIG. 9A, the content holding node device 1K transmits a registration message to the node device 1P according to the routing table of its own node device. When the node device 1P receives the registration message, the node device 1P acquires the index information included in the registration message and becomes a cache node device of the content “1231”. Further, the node device 1P transmits a registration message to the node device 1R according to the routing table of the own node device. When the node device 1R receives the registration message, the node device 1R acquires the index information included in the registration message and becomes a cache node device of the content “1231”. Furthermore, the node device 1P transmits a registration message to the node device 1H according to the routing table of the node device of its own. When the node device 1H receives the registration message, the node device 1H acquires the index information included in the registration message and becomes a cache node device of the content “1231”. Further, the node device 1H has the identification information of the root node device 1E in its own routing table, and transfers the registration message transmitted from the content holding node device 1R to the root node device 1E.

  FIG. 9B represents FIG. 9A in a tree structure as a route through which the content search message is transferred. As described above, the content data management device 10 selects the node device 1K having a node ID whose top digit is different from the node ID of the root node device 1E, and determines it as a content holding node device. Since the data is transferred to the root node device via the device, a large number of cache node devices can be arranged. Therefore, when an arbitrary request node transmits a content search message, it is possible to increase the possibility that the content search message is received by the cache node device before reaching the root node device 1E. It is possible to reduce the time it takes. For example, when the request node device 1J issues a search message, 1H returns a response message in the example of FIG. 8B, and 1P returns a message in the example of FIG. 9B. The response time is shorter in the example of b).

  When a plurality of content holding node devices are arranged, node devices having different node IDs in the first first digit are determined as content data holding node devices. FIG. 10A shows that when the content data management device 10 determines three node devices 1K, 1U, and 1T as content holding node devices, these content holding node devices transmit a registration message to the root node device. The cache node device is arranged.

  As shown in FIG. 10 (a), the content data management apparatus 10 has node devices 1K and 1S having node IDs “0xxx”, “2xxx”, and “3xxx” that are different from the content “1231” in the most significant digit. , 1T are selected and determined as content holding node devices. When the content holding node device is thus determined, the content data management device 10 distributes the data of the content “1231” to the node devices 1K, 1S, and 1T, respectively. The node devices 1K, 1S, and 1T that have become the content holding node devices by receiving and storing the data of the content “1231” from the content data management device 10 transmit a registration message to the root node device 1E. In FIG. 10B, the registration message from the content holding node device 1K passes through the node devices 1P, 1R, and 1H, and the registration message from the content holding node device 1S passes through the node devices 1U and 1W. The registration message from the content holding node device 1T reaches the root node device 1E via the node devices 1V and 1H, whereby the node devices 1P, 1R, 1H, 1U, 1W and 1V are cache node devices. Will be arranged as.

  FIG. 10B represents FIG. 10A in a tree structure as a route through which the content search message is transferred. In this way, the content data management device 10 selects the node devices 1K, 1S, and 1T having the node IDs “0xxx”, “2xxx”, and “3xxx” that are different in the most significant digit from the content ID, and serves as the content holding node device. By determining, the registration message is transferred to the root node device via many node devices, and a large number of cache node devices are arranged. Therefore, the possibility of receiving the content search message in the cache node device before reaching the root node device 1E can be increased, and the time required for content search can be reduced. In addition, the node device close to the root node device has a reduced opportunity to transfer the content search message. Therefore, the load on the node device close to the root node device can be reduced.

  Note that the content data management apparatus 10 is equal to or greater than the number of upper digits (for example, when the node space is generated in quaternary numbers as in the present embodiment, the number of upper digits is 4.) When content holding node devices are arranged, content holding node devices less than the number of upper digit values are arranged as described above, and content holding node devices greater than the number of upper digit values are randomly determined. Therefore, even when a large number of content holding node devices are arranged in the content distribution system, it is not necessary to hold the node IDs of the already arranged content holding node devices more than the number of upper digits, and therefore the content The calculation load of the data management apparatus 10 can be reduced.

[2. Description of Configuration of Content Data Management Device 10]
Next, the configuration and operation of the content data management apparatus 10 will be described with reference to the drawings. FIG. 11 is a diagram showing a schematic configuration of the content data management apparatus 10 in the content distribution system S according to the present embodiment.

  The content data management apparatus 10 can be a general server computer in addition to a dedicated computer. As shown in FIG. 11, the content data management apparatus 10 can be rewritten to store (store) a CPU (Central Processing Unit) 102 and various programs. A first storage unit 103 as a main storage device, a second storage unit 104 composed of an HDD or the like for storing various data, and other node devices 1 participating in the network 8 via the router 120 A network interface 105 for communicating with each other, a mouse 107a and a keyboard 107b as input means for inputting information for controlling the content data management apparatus 10 by an administrator of the content distribution system S, and an input means Peripheral device control chip 106 for processing input information, and CPU 102 The image data is received, written to an internal video memory (not shown), and the video chip 108 is displayed to display the data written in the video memory on a display 109 to be described later. They are connected to each other via a system bus 101. In the present embodiment, the CPU 102 and the first storage unit 103 constitute a control unit 114.

(Regarding the first storage unit 103)
The first storage unit 103 also has an operating system (OS) program 110 for providing basic functions of the node device 1 as a computer, a screen control program 111 for controlling the display 109, etc., and content distribution Stores a catalog update program 112 for updating a catalog list, which is a list of contents each time content is input to the system S, a new input content program 113 for newly inputting content to the content distribution system S, and the like. These are read by the CPU 102, and the function according to these programs is executed by the CPU 102. Note that “injecting content into the content distribution system S” means that the content data management device 10 determines a node device 1 that is a content holding node device for a certain content, and distributes the content data to the determined node device 1. Means that.

  Here, the OS program 110 is read and executed by the CPU 102, whereby a function related to the mouse 107 a and the keyboard 107 b and a content data management device such as memory management such as the first storage unit 103 and the second storage unit 104. The basic function of the computer 10 can be executed. Then, in a state where the OS program 110 is executed by the CPU 102, the above-described screen control program 111, catalog update program 112, new input content program 113, and the like are read from the first storage unit 103 and executed.

  The OS program 110, the screen control program 111, the catalog update program 112, the newly input content program 113, and the like are downloaded to the first storage unit 103 via the network interface 105 from, for example, a server connected to the network 8. Alternatively, it may be recorded on a recording medium such as a CD-ROM and then read into the first storage unit 103 via a drive of the recording medium.

(About the second storage unit 104)
The second storage unit 104 includes a catalog list storage area 115 for storing a catalog list in which contents generated by the catalog update program and provided in the content distribution system S are listed, and provided in the content distribution system S. A content data storage area 116 that stores the data of the content that has been stored, and a new content data storage area 117 that serves as content data storage means for storing content data that is newly provided in the content distribution system S. ing.

(Regarding the control means 114)
The control unit 114 includes the CPU 102 and the first storage unit 103 as described above, and the CPU 102 reads out and executes the various programs 110 to 113 stored in the first storage unit 103, whereby the entire node device 1 is configured. It performs overall control and functions as display control means, content data identification information determination means, content holding node device determination means, content holding request means, and the like, which will be described later.

  The CPU 102 executes the screen control program 111 as a display control unit or the like, the CPU 102 executes the catalog update program 112 as a catalog update unit or the like, and the CPU 102 executes the new input content program 113. , Functioning as content data identification information determining means, content holding node device determining means, content holding request means, and the like.

(Display control means)
The display control means has a function of controlling the video chip 108 and the display 109 to display various video information (image information). In other words, the display control means controls how video is displayed on the display 109.

(About content data identification information determination means)
The content data identification information determination unit has a function of determining a content ID that is identification information of content data to be newly input to the content distribution system S.

  More specifically, the content data identification information determination means calculates a random value by a random calculation, and hashes the value calculated in this way with a hash function that is common to when obtaining the node ID. To determine the content ID.

(About content holding node device determination means)
The content holding node device determination means has a function of determining a node device that holds content data stored in the new content data storage area 117, that is, a content holding node device.

  When determining the content holding node device, the content holding node device determining means calculates a node ID (identification information) having a predetermined relationship with the content ID that is identification information of the content data to be held. The node device 1 having the calculated node ID is set as a content holding node device.

  More specifically, the content holding node device determination means sets, as the content data holding node device, the node device 1 having a node ID whose upper first digit information is different from the content ID of the content data to be held. decide. For example, when content data whose content ID is “1231” is held, node IDs “0xxx” and “2xxx” having first digit information different from “1” that is the first digit information of the content ID. , “3xxx” (x is an arbitrary value from 0 to 3) is selected, and determined as a content holding node device.

  Further, when a plurality of content holding node devices are determined, the node device 1 having a different node ID in the first first digit is determined as the content data holding node device. For example, when the content data having the content ID “1231” is held in the three node devices 1, the node ID having the first digit information different from the first digit information “1”. Three node devices 1 having “0xxx”, “2xxx”, and “3xxx” (x is an arbitrary value from 0 to 3) are determined as content holding node devices.

  Further, the number of content holding node devices to be determined is equal to or greater than the number of values in the upper first digit (for example, when the node space is generated in quaternary numbers as in this embodiment, the number of values in the upper digits is 4). When the content holding node device is equal to or more than the number of the first digit value, a random node ID is calculated by random calculation, and the node having the node ID calculated at random in this way. The device 1 is determined as a content holding node device.

(About content retention request means)
The content holding request unit makes a content data holding request to the content holding node device determined by the content holding node device determining unit. In the present embodiment, this content data holding request is a request for holding content data to the node device that should be the content holding node device determined as described above, and is transmitted by DHT routing. In response to this request, the node device that should be the content holding node device extracts the IP address of the content data management device 10 from the content data holding request, and transmits the content data corresponding to the holding request to the IP address. Send a request. When receiving the content data transmission request, the content retention request means transmits the content data to be retained to the transmission request source node device. As described above, in communication between the content data management device 10 and the node device 1, a plurality of types of communication modes such as communication using DHT routing and one-to-one communication can be appropriately used.

[3. Explanation of Configuration of Node Device 1]
Next, the configuration and operation of the node device 1 will be described with reference to the drawings. FIG. 12 is a diagram showing a schematic configuration of the node device 1 in the content distribution system S according to the present embodiment.

  The node device 1 is applicable to a general personal computer in addition to a dedicated computer. As shown in FIG. 12, a rewritable main memory that stores (stores) a CPU (Central Processing Unit) 202 and various programs. Between the first storage unit 203 as a storage device, the second storage unit 204 configured by an HDD or the like for storing various data, and other node devices 1 participating in the network 8 via the router 224 A network interface 205 for communicating with the remote controller, a remote controller 206 for transmitting and receiving a predetermined infrared signal for remotely operating the node device 1 by a user, an infrared port 207 for communicating with the remote controller 206 by infrared rays, The peripheral device control chip 208 for controlling the infrared port 207 and the control of the CPU 202 A video chip 209 that receives image data, writes it in an internal video memory (not shown), and displays the data written in the video memory on a display 210 described later, and a sound source such as an FM sound source or a Wave Table sound source; And a sound source chip 211 that outputs sound waves from the speaker 212 by outputting an audio signal to the speaker 212, and these various components are connected to each other via a system bus 201. In the present embodiment, the CPU 202 and the first storage unit 203 constitute a control unit 213.

(Regarding the first storage unit 203)
The first storage unit 203 also includes an operating system (OS) program 214 for providing basic functions of the node device 1 as a computer, a screen control program 215 for controlling the display 210, and the like, content holding Stream for streaming receiving content data transmitted from another node device functioning as a node device, and streaming distribution of content data stored in the second storage unit 204 when the own node device functions as a content holding node device A control program 216, a message management program 217 for transmitting / receiving messages to / from other node devices, a player program 218 for reproducing distributed content data, and the like are stored in the CPU 202. Read I, and functions according to the program by the CPU202 is executed. The first storage unit 203 further includes an index table storage unit 219 for storing an index table (see FIG. 7) and a routing table storage unit 220 for storing a routing table (see FIG. 4). Yes.

  Here, the OS program 214 is read and executed by the CPU 202, thereby causing the node device 1 such as a function related to input / output of the remote controller 206 or memory management such as the first storage unit 203 and the second storage unit 204. It enables the basic functions of a computer to be executed. Then, with the OS program 214 being executed by the CPU 202, the screen control program 215, the stream control program 216, the message management program 217, the player program 218, etc. are read from the first storage unit 203 and executed. .

  Note that the OS program 214, the screen control program 215, the stream control program 216, the message management program 217, the player program 218, etc. are sent from the first storage unit via the network interface 205 from a server or the like connected to the network 8, for example. The program may be downloaded to the storage unit 203, or may be recorded on a recording medium such as a CD-ROM and then read into the first storage unit 203 via the drive of the recording medium.

(About the second storage unit 204)
In the second storage unit 204, a catalog list storage area 222 for storing a catalog list in which contents input from the content data management apparatus 10 and provided in the content distribution system S are listed, and the content data management apparatus The content data storage area 223 and the like function as content data storage means for storing content data distributed from 10 and the like.

(Regarding the control means 213)
The control unit 213 includes the CPU 202 and the first storage unit 203 as described above, and the CPU 202 reads and executes the various programs 214 to 218 stored in the first storage unit 203, whereby the entire node device 1 is configured. Centralized control and display control means, stream control means, message destination determination means, message transfer means, content data acquisition means, registration message generation means, registration message transmission means, deletion message generation means, deletion message transmission means, which will be described later, It functions as content holding node information acquisition means, content holding node request information generation means, content holding node request information transmission means, determination means, node identification information transmission means, decoding means, content reproduction means, and the like.

  When the CPU 202 executes the screen control program 215, the CPU 202 executes the message management program 217 as a display control unit or the like, and when the CPU 202 executes the stream control program 216 or as the stream control unit or the like. Message destination determination means, message transfer means, content data acquisition means, registration message generation means, registration message transmission means, deletion message generation means, deletion message transmission means, content holding node information acquisition means, content holding node request information generation means , Content holding node request information transmission means, determination means, node identification information transmission means, etc., and when the CPU 202 executes the player program 218, the decoding means and the computer As Ntsu reproduction control unit or the like, and functions, respectively.

(Display control means)
The display control means has a function of controlling the video chip 209 and the display 210 to display various video information (image information). That is, the display control unit controls how the video is displayed on the display 210.

(Stream control means)
The stream control means includes content data receiving means for receiving content data streamed from another node apparatus 1 and content data delivery means for streaming content data stored in the second storage unit 204 to the other node apparatus 1. And so on.

  When it is determined that the packet distributed from the other node device 1 is a content packet, the content data receiving means receives the content packet one by one and temporarily stores it in a ring buffer of the first storage unit 203 (not shown). And then stored in the second storage unit 204. Further, the content distribution unit converts the content data stored in the second storage unit 204 into a content packet, and transmits the content packet to another node device 1 via the network interface 205 one by one. The content data receiving means and the content data distribution means can use a known streaming distribution protocol or a unique dedicated protocol.

(About message destination determination means)
The message destination determination unit determines whether the received message is addressed to the own node device 1 based on the destination identification information of the message received via the network 8 and the routing table. The message determined by the message destination determination means includes a content search message for requesting the identification information of the content holding node device from the root node device, a registration message for registering the identification information of the content holding node device in the root node device, etc. It is.

  Whether or not the received message is addressed to the own node apparatus 1 is determined by taking out a destination node ID (destination identification information) included in the message, and controlling means described later based on the routing table stored in the first storage unit 203 213 determines. That is, when various messages are received via the network interface 205, the message destination determination unit compares the destination identification information included in the received message with the node ID stored in the routing table, and determines the destination identification included in the message. If it is determined that the node ID on the routing table closest to the information is the node ID of the own node device 1, it is determined that the message is addressed to the own node device 1.

(About message transfer means)
When the message transfer means determines that the message received via the network 8 is not addressed to its own node device by the message destination determination means, the node stored in the routing table based on the destination identification information of the received message A destination node device is selected from the device identification information, and the received message is transferred to the destination node device. That is, the message transfer means selects the node ID close to the destination identification information from the node IDs of the node devices stored in the routing table, knows the IP address of the node device corresponding to the node ID thus selected, The message is transferred with the IP address as the destination of the IP packet.

(About content data acquisition means)
When the message received via the network interface 205 is a content data retention request from the content data management device 10, the content data acquisition means sends content data corresponding to the content data retention request to the content data management device 10. Get from. And the acquired content data is memorize | stored in the 2nd memory | storage part 204 which is a content data storage means. As described above, the content data holding request is transmitted and received by DHT routing, and the content data is transmitted and received by one-to-one communication.

(Registration message generation means)
When the content data received from the content data management device 10 is stored in the second storage unit 204 that is the content data storage means, the registration message generation means uses the content ID that is identification information of the content data as destination identification information, and A registration message including a node ID and an IP address that are identification information of the node device 1 is generated. Similarly, when content data is received from another content holding node device, the received content data is stored in the second storage unit 204 as content data storage means, and a registration message is generated.

(Registration message transmission means)
The registration message transmission unit is configured to transmit the registration message generated by the registration message generation unit based on the content ID of the content data stored in the second storage unit 204 based on the identification information of the node device stored in the routing table. Select and send. For example, in the case where a routing table as shown in FIG. 4 is provided and the content ID of the content data stored in the second storage unit 204 is “1231”, the registration message transmission means reads the node ID “ 1221 ”is selected as the destination node device, and the IP address“ 21.13.21.13 ”of the node device with the node ID“ 1221 ”is extracted. Then, the registration message is transmitted using the IP address “21.13.21.13” as the destination node device. The destination identification information of this registration message is “1231”.

(About deletion message generation means)
When the deletion message generation unit deletes the content data stored in the second storage unit 204 that is the content data storage unit, the content ID that is identification information of the content data and the node ID that is identification information of the node device 1 itself And a delete message including the IP address.

(About deletion message sending means)
The deletion message transmission unit is configured to transmit the deletion message generated by the deletion message generation unit based on the content ID of the content data deleted from the second storage unit 204 based on the identification information of the node device stored in the routing table. Select and send. For example, when the content ID of the content data deleted from the second storage unit 204 is “1231” having the routing table as shown in FIG. 1221 ”is selected as the destination node device, and the IP address“ 21.13.21.13 ”of the node device with the node ID“ 1221 ”is extracted. Then, the delete message is transmitted with the IP address “21.13.21.13” as the destination node device. Note that the destination identification information of this deletion message is “1231”.

(About content holding node information acquisition means)
When the received message is a registration message in the own node device 1, the content holding node information acquisition means also includes a node ID, an IP address, etc., which are identification information of the content holding node device included in the registration message, in the same registration message. Index information consisting of a set of included content IDs is acquired. Then, the index information acquired in this way is stored in the index table storage unit 219 which is a content holding node information storage unit.

(About content holding node request information generation means)
The content holding node request information generating unit generates a content search message. For example, after a catalog list received from the content data management apparatus 10 is displayed on the display 210, when a desired content is selected from the catalog list by an operation of the remote controller 206 by the user of the node apparatus 1, a content holding node request The information generation means generates a content search message that is content holding node request information for searching for location information of the content holding node device that holds the selected content. The content search message is a message in which the content ID that is the identification information of the requested content data is the destination identification information, and the node ID that is the identification information of the own node device 1 is the request source identification information.

(About content holding node request information transmission means)
The content holding node request information transmitting means selects the destination node device from the node ID that is the node device identification information stored in the routing table based on the content data identification information that is the destination identification information of the content search message and the predetermined condition. Then, a content search message that is content holding node request information is transmitted. Here, the “predetermined condition” is a condition for selecting a node ID whose upper digits more match the content ID, which is the destination identification information of the content search message, among the node IDs stored in the routing table. For example, when the routing table as shown in FIG. 4 is provided and the content ID as the destination identification information is “1231”, the content holding node request information transmitting unit obtains the node ID “1221” from the routing table. Select as the destination node device, and take out the IP address “21.13.21.13” of the node device with the node ID “1221”. Then, the content search message is transmitted using the IP address “21.13.21.13” as the destination node device.

(About judgment means)
When the node device 1 receives a content search message that is content holding node request information via the network interface 205, the determining means is index information stored in a routing table that is content holding node information storage means, that is, content. It is determined whether or not the node ID of the holding node device includes information that matches the node ID of the content holding node device for the requested content.

(About node identification information transmission means)
If the node ID of the content holding node device corresponding to the content requested by the content search message is stored, the node identification information transmission means uses the node ID of the content holding node device to transmit the content search message. Send to. The transmission destination node device at this time is a node device selected from the routing table in the same manner as other messages based on the transmission source identification information included in the content search message, that is, the identification information of the request node device. By transmitting in this way, the node ID of the content holding node device is delivered to the transmission source node device of the content search message.

(Decoding means)
The decoding means displays the content data transmitted from the other node device 1 on the display 210 and decodes it for output from the speaker 212. That is, the content data transmitted from the other node device 1 is encoded in a data format for streaming delivery, for example, a data format such as ASF, WMA, WMV, etc., and the encoded content data is displayed on the display 210. And decoding so that it can be output from the speaker 212.

(About content playback means)
The content reproduction means reproduces the content data sequentially stored in the buffer area including the ring buffer of the first storage unit 203 by the content reproduction means. At this time, the control means 213 is based on the stream control program 216. Then, the content data is reproduced by operating the video chip 209 and the sound source chip 211.

[4. Description of processing of content data management apparatus 10]
Hereinafter, the detailed operation of the content data management apparatus 10 will be described more specifically with reference to the flowcharts of FIGS. FIG. 13 is a flowchart showing a main process at the time of content input in the content data management apparatus, FIG. 14 is a flowchart showing a content input process when the number of contents to be input is less than X (the number of upper digits), and FIG. It is a flowchart which shows a content input process when the number of the content to input is X or more.

  First, the control unit 114 determines whether or not a content input process has been selected by an operation of an administrator of the content data management apparatus 10 (step S11). For example, in order for the administrator of the content data management apparatus 10 to input new content data stored in the new content data storage area 117 into the content distribution system S by operating input means such as the mouse 107a and the keyboard 107b. When the new content data is designated and the number of content holding node devices to hold the designated content data is designated, the control means 114 determines that the content input processing has been selected.

  If it is determined that the content input process has been selected (step S11: Yes), the control unit 114 randomly determines the content ID of the new content data to be input (step S12). In addition, it is desirable that the randomness at this time is not biased in the content ID space.

  When the content ID of the new content to be input to the content distribution system S is determined, the control unit 114 determines that the content input number, in other words, the number of content holding node devices that hold the content data is X (the number of upper digits). It is determined whether it is less than (step S13). In the present embodiment, the node ID, which is the identification information of the node device 1, is expressed in a quaternary number, so the number X of the upper digit value is 4.

  In step S13, when the control unit 114 determines that the number of input contents is less than X (step S13: Yes), the process of “processing where the input number is less than X” (step S14) is performed. On the other hand, if it is determined that the number of input contents is equal to or greater than X (step S13: No), the control unit 114 performs “processing where the number of input is equal to or greater than X” (step S15).

  If it is determined in step S11 that the content input process is not selected (step S11: No), the control unit 114 performs other processes (step S16). Note that when the processing of steps S14 to S16 is completed, the control unit 114 repeats the processing from step S11.

(Processing with less than X inputs)
Next, with reference to FIG. 14, the process when the number of contents input is less than X (the process in step S14 described above) will be described.

  First, the control means 114 clears the value of the input number counter and sets it to 0 (step S20), and then randomly selects a content holding node device that holds new content data to be input (step S21).

  Then, the control means 114 compares the node ID of the content holding node device selected at random in this way with the content ID of the content to be input, and the upper first digit of the node ID and the upper first digit of the content ID. Are different from each other (step S22). If it is determined that the first digit of the node ID is different from the content ID (step S22: Yes), the control unit 114 sets the node ID of the node device that is currently arranged as the content holding node device that has already input the new content data to be input. It is determined whether or not the upper first digit is different from the upper first digit of the node ID of the content holding node device selected in step S21 (step S23).

  If it is determined that the upper first digit of the node ID of the content holding node device selected in step S21 is different from the upper first digit of the node ID of the content holding node device already input (step S23: Yes), control is performed. The means 114 makes a request for holding new content data to the content holding node device selected in step S21, and transmits the new content data together with the content ID (step S24). Thereafter, the control unit 114 increments the value of the insertion number counter by +1 (step S25), and determines whether or not the value of the insertion number counter is smaller than the number of contents input (step S26).

  When it is determined in step S22 that the first digit of the node ID and the content ID are the same (step S22: No), or the node IDs of the content holding node device selected in step S21 and the content holding node device already input When it is determined that the upper first digit is the same (step S23: No), or when the value of the input number counter is smaller than the content input number (step S26: Yes), the control unit 114 starts from step S21. Repeat the process. When the value of the input number counter becomes equal to or greater than the content input number (step S26: No), the control unit 114 ends the process when the content input number is less than X.

(About processing with more than X inputs)
Next, with reference to FIG. 15, a process when the number of contents input is X or more (the process in step S15 described above) will be described.

  First, the control means 114 clears the value of the input number counter and sets it to 0 (step S30), and then determines whether or not the value of the input number counter is smaller than X (step S31).

  When the value of the input number counter is smaller than X (step S31: Yes), the control unit 114 selects a node device having a node ID whose first digit starts with “counter value” as a content holding node device (step S32). ) When the value of the insertion number counter is equal to or greater than X (step S31: No), the control unit 114 selects a node device having a randomly calculated node ID as the content holding node device (step S33).

  After selecting the content holding node device in steps S32 and S33, the control unit 114 makes a request for holding new content data to the content holding node device selected in step S21, and sends the new content data to the content holding node device. Is transmitted (step S34). Thereafter, the control unit 114 increments the value of the insertion number counter by +1 (step S35), and determines whether or not the value of the insertion number counter is smaller than the number of contents input (step S36).

  When the value of the input number counter is smaller than the content input number (step S36: Yes), the control unit 114 repeats the processing from step S31, and when the value of the input number counter is equal to or greater than the content input number ( Step S36: No), the control means 114 ends the process when the number of contents input is X or more.

  As described above, the content data management apparatus 10 according to the present embodiment uses a node ID that is identification information of a content holding node apparatus that holds content data, and a node ID that has a predetermined relationship with the content ID that is identification information of the content data. Since the content holding node device is arranged by making a content data holding request using the determined node ID as the destination identification information, the number of times the registration message transmitted from the content holding node device is transferred increases. Many cache node devices are arranged. As a result, the content search message from the request node device that searches for content is more likely to reach the cache node device before reaching the root node device, and the time required for content search is reduced overall. become. In addition, a node device close to the root node device has a reduced chance of transferring a content search message for searching for content. Therefore, the load on the node device close to the root node device can be reduced.

[5. Description of processing of node device 1]
Hereinafter, the detailed operation of the node device 1 will be described more specifically with reference to the flowchart of FIG. FIG. 16 is a flowchart showing main processing in the node device.

  First, the control unit 213 determines whether or not the power supply of the node device 1 has shifted to the OFF state (step S100). If it is determined that the power supply of the node device 1 has not shifted to the OFF state, that is, it is determined that the node device 1 is in the ON state (step S100: No), the control unit 213 next receives a registration message or a deletion message. Is determined (step S101). On the other hand, when determining that the power supply of the node device 1 has shifted to the OFF state (step S100: Yes), the control unit 213 stops the control.

  When a registration message or a deletion message is received (step S101: Yes), the control unit 213 further determines whether or not the message is a registration message (step S102), and when the received message is a registration message. (Step S102: Yes), the index information (content ID, content holding node device identification information, etc.) included in the registration message is registered in the index table as a cache (Step S103). On the other hand, when the received message is a deletion message (step S102: No), the control unit 213 deletes the cache corresponding to the index information requested to be deleted by the deletion message from the routing table (step S104).

  When the processing for the registration message or the deletion message (steps S103 and S104) ends, the control unit 213 determines whether or not the own node device is a root node device corresponding to the message (step S105). In other words, it is determined whether or not the message is a message in which the own node device is the root node device. If it is determined that the message is not addressed to the root node device (step S105: No), the control unit 213 extracts the node ID and IP address of the next transfer destination node device from the routing table, and sends them to the transfer destination node device. On the other hand, the received registration message or deletion message is transferred (step S106).

  If it is determined in step S101 that a registration message or a deletion message has not been received (step S101: No), the control unit 213 has received a packet of content data requested from the content holding node device. Is determined (step S107). If it is determined that a packet of content data has been received (step S107: Yes), the received content data is stored in the second storage unit 204 (step S108). Next, the control means 213 determines whether or not all content data packets have been received, that is, whether or not one content data has been received (step S109). If it is determined that all of the content data has been received (step S109: Yes), the control unit 213 transmits a registration message with the content ID of the received content as destination identification information. That is, a registration message is transmitted to the root node device of the received content (step S110).

  If it is determined in step S107 that the requested content data packet has not been received (step S107: No), it is determined whether the content data packet input by the content data management apparatus 10 has been received (step S111). . If it is determined that the content data packet input by the content data management apparatus 10 has been received (step S111: Yes), the control unit 213 proceeds to step S108. On the other hand, when it is determined that the content data packet input by the content data management apparatus 10 has not been received (step S111: No), other processing is performed (step S112).

  When the processing of steps S106, S110, and S112 is completed, or when it is determined in step S105 that the own node device is the root node device (step S105: Yes), or all content data is not received in step S109. (Step S109: No), the process proceeds to step S100.

  As described above, when the node device 1 in the present embodiment stores the content data in the second storage unit 204, the node device 1 generates and transmits a registration message. When the node device 1 receives the registration message, the node device 1 is the root node device. Regardless of whether or not, the index information included in the received registration message is registered in the index table so as to function as a cache node device. Therefore, the node ID or IP address of the content holding node device can be returned as a cache node device in response to the content search message from the request node device that searches for content, and the time required for content search can be reduced. it can.

[6. Application to other types of content distribution systems]
In the above embodiment, the present invention is applied to a pastry type or tapestry type content distribution system. However, the present invention is also applied to a content distribution system such as a kademlia type, a chord type, a Vicery type, or a CAN type that has a different message transfer method. The present invention is applicable.

  Hereinafter, an example in which the present invention is applied to a kademlia type content distribution system and a chord type content distribution system will be described.

In the kademlia type content distribution system, each node device 1 stores, as a list, information (IP address and node ID) of a node device that is a predetermined number or less according to the distance from the node device 1 as a list. I remember it. For example, in FIG. 17A, the node device 1a ′ having the node ID “101” arranged in the 3-bit ID space has a distance [2 ⁱ , 2 ^{i + 1} −1] as shown in FIG. It has up to two pieces of node device information (0 ≦ i ≦ 2), and these are stored as a list. In this list, the information of the node ID “100” as the node device having the distance [1], the information of the node IDs “110” and “111” as the node devices having the distance [2-3], and the distance [4-7]. As node devices, information (for example, IP addresses) of node IDs “000” and “011” is registered in association with the distance together with the node ID. In FIG. 17A, the ID space is expressed as a tree structure for ease of explanation.

  Then, the node device uses this list instead of the routing table to transfer the message. For example, in the case of a registration message, the node ID of the node device registered in the list has the node ID closest to the content ID that is the destination identification information of the registration message, that is, the node ID having the smallest logical sum with the content ID. Forward the message to the node device.

  When the present invention is applied to the kademlia type content distribution system configured as described above, the control unit 114 of the content data management apparatus 10 has a predetermined relationship with the content ID of the content data to be held. That is, the node device having the node ID with the largest exclusive OR is determined as the content data holding node device. For example, in FIG. 17, when the content ID is “010”, the node device having the node ID closest to ID “101” having the largest numerical difference from this ID “010” is determined as the content holding node device. To do. By determining the content holding node device in this way, more cache node devices can be arranged.

  Also, in the chord type content distribution system, each node device 1 uses the finger table to specify the node ID and IP address of the node device that is separated from the node device by one factorial of 2 of the size of the ID space in the ID space. Is held in a table called For example, as shown in FIG. 18, the ID space is 64 (the IDs of N1 to N64 exist), and the finger table of the node device with the node ID “N8” is separated by ½ of the size of the ID space. Holds the IP address of the node device having the node ID “N42” closest to the node ID “N40”, and is also closest to the node ID “N24” separated by ¼ of the size of the ID space. The IP address of the node device with the node ID “N28”, the IP address of the node device with the node ID “N21” closest to the node ID “N16” separated by 1/8 of the size of the ID space, and the size of the ID space The IP address of the node device with the node ID “N14” closest to the node ID “N12” separated by 1/16, the closest to the node ID “N10” separated by 1/32 of the size of the ID space IP address of the node device of the node ID "N14", holds the IP address of the node device of the node ID closest to 1/64 apart node ID of the size of the ID space "N9", "N14".

  Then, the node device uses this finger table to transfer messages instead of the routing table. For example, in the case of a registration message, the message is transferred to the node device having the largest node ID that does not exceed the content ID that is the destination identification information of the registration message among the node IDs of the node devices registered in the finger table. Therefore, the message can be transferred to the node device that halves the remaining ID space for the content ID, and the message is transferred to the destination node device in this way.

  When the present invention is applied to the chord type content distribution system configured as described above, the control unit 114 of the content data management apparatus 10 has a predetermined relationship with the content ID of the content data to be held. That is, the node device having the node ID having the largest numerical difference is determined as the content data holding node device. For example, in FIG. 18, when the content ID is “N8”, the node device having the node ID “N42” closest to the ID “N40” that has the largest numerical difference in view of the ID “N8” is the content holding node. It is determined as a device. By determining the content holding node device in this way, more cache node devices can be arranged.

  In the present embodiment, the content data management apparatus 10 randomly determines the content ID of the new content data to be input, but the content name (content title) of the new content data to be input and summary information of the content The content ID may be determined by hashing a keyword such as (summary) with a hash function common to the node ID. In this way, it is not necessary to place the content ID in the catalog list, and the information in the catalog list can be reduced. Note that even if the content data is different, it is assumed that the same keyword (for example, the name of the content) is used. In this case, the hash value is the same to avoid the same hash value. The keyword may be, for example, a combination of content name and copyright information (for example, performer name, director name, original author name, singer name, composer name, or songwriter name).

  Further, as described above, if the keyword such as the content name of the content data is hashed by the hash function common to the case of obtaining the node ID and the content ID is determined, the node device can calculate the hash function using the hash function. By providing this, there is no need to acquire a content ID from the content data management device. In other words, content identification information calculation means is provided for calculating the content data specific information by using the same hash function as the hash function for calculating the node ID to obtain the content ID that is the identification information of the content data.

  In the present embodiment, the content data management device 10 determines the content holding node device. However, a part or all of the functions of the content data management device 10 may be built in the root node device. . For example, the content data management device 10 has a function of distributing content data to the root node device, while the root node device stores content data that is received from the content data management device 10 and is a management target of the local node device, The content data received from the content data management device 10 is transmitted using a node device having a node ID having a predetermined relationship with the content ID of the content data as a content holding node device. In this way, the node device may be provided with a function as a content data management device for arranging the content holding node device.

It is a figure which shows an example of the connection aspect of each node apparatus in the content delivery system which concerns on this embodiment. It is explanatory drawing of ID space. It is a figure which shows an example of a mode that a routing table is produced by DHT. It is an example of the routing table of the node apparatus which concerns on this embodiment. It is a figure which shows an example of a mode that the node apparatus 1 which is the holding | maintenance source of content data is searched by DHT. It is the figure which represented a mode that the registration message of a content holding node was transferred in the spanning tree shape. It is an example of the index table of the node apparatus which concerns on this embodiment. It is a figure which shows the method of distributing content data at random. It is a figure which shows the distribution method of the content data which concerns on this embodiment. It is a figure which shows the distribution method of the content data which concerns on this embodiment. It is a figure which shows the example of schematic structure of the content data management apparatus in this embodiment. It is a figure which shows the example of schematic structure of the node apparatus in this embodiment. The flowchart which shows the main process in a content data management apparatus. The flowchart which shows the process in which the insertion number in a content data management apparatus is less than X. The flowchart which shows the process in which the input number in a content data management apparatus is X or more. The flowchart which shows the main process in a node apparatus. It is a figure for demonstrating a kademlia type content delivery system. It is a figure for demonstrating a chord type | mold content delivery system.

Explanation of symbols

1 Node device 8 Network 10 Content data management device 102 Node device CPU
DESCRIPTION OF SYMBOLS 103 1st memory | storage part of node apparatus 104 2nd memory | storage part of node apparatus 114 Control means of node apparatus 202 CPU of content data management apparatus
103 First Storage Unit of Content Data Management Device 104 Second Storage Unit of Content Data Management Device 113 Control Unit of Content Data Management Device S Content Distribution System

Claims (6)

A plurality of node devices connected to each other via a network, and a content holding node device for storing content data to be shared among the plurality of node devices, a part of the plurality of node devices. A content data management device for storing the content data in the part of the node devices,
The plurality of node devices are node identification information for identifying the plurality of node devices, and the node identification information composed of a predetermined number of digits is given,
The content data distributed in the content distribution system is provided with content identification information configured with a predetermined number of digits and identifying the content data,
A root node device that stores location information indicating the location in the network of the content holding node device that holds the content data is determined for each content data,
A node device to which the node identification information having a difference between the content data held by the content holding node device and the content identification information is within a predetermined range is determined as the root node device;
A message transmitted from the content holding node device to the root node device,
When at least one node device of the plurality of node devices receives a message including the location information of the content holding node that transmitted the message, the node device that has received the message transmits the message to the plurality of node devices. A content delivery system that transfers the location information included in the received message to the at least one node device ,
The content data management device includes:
Content data storage means for storing the content data;
Content identification information for identifying the content data distributed in the content distribution system, content data identification information determination means for determining the content identification information composed of a predetermined number of digits,
Content data storage means for storing the content data;
A content holding node device for holding content data stored in the content data storage means, wherein the node has the node identification information whose upper first digit information is different from the content identification information of the content data to be held Content holding node device determination for determining a device, or a node device having the node identification information having the largest exclusive OR, or a node device having the node identification information having the largest numerical difference as the content holding node device Means,
Content holding request means for making a content data holding request to the content holding node apparatus determined by the content holding node apparatus determining means,
The node device is
Receiving means for receiving the holding request;
Content data storage means for storing content data corresponding to the content data holding request when the receiving means receives the holding request;
Registration message transmission for transmitting a registration message including the location information of the node device storing the content data to the root node device of the stored content data when content data is stored in the content data storage means Means,
A content distribution system comprising: A plurality of node devices connected to each other via a network, and a content holding node device for storing content data to be shared among the plurality of node devices, a part of the plurality of node devices. A content data management device for storing the content data in the part of the node devices,
The plurality of node devices are node identification information for identifying the plurality of node devices, and the node identification information composed of a predetermined number of digits is given,
The content data distributed in the content distribution system is provided with content identification information configured with a predetermined number of digits and identifying the content data,
A root node device that stores location information indicating the location in the network of the content holding node device that holds the content data is determined for each content data,
A node device to which the node identification information having a difference between the content data held by the content holding node device and the content identification information is within a predetermined range is determined as the root node device;
At least one node device of the plurality of node devices transmits a message transmitted from the content holding node device to the root node device, the message including the location information of the content holding node that has transmitted the message. when receiving, the node device receiving the message, the message, along with transfers to at least one node device of said plurality of node devices, to have contact to the content distribution system that stores the location information in which the received message contains ,
The content data management device includes :
Content identification information for identifying the content data distributed in the content distribution system, content data identification information determination means for determining the content identification information composed of a predetermined number of digits,
Content data storage means for storing the content data;
A content holding node device for holding content data stored in the content data storage means, wherein the node has the node identification information whose upper first digit information is different from the content identification information of the content data to be held Content holding node device determination for determining a device, or a node device having the node identification information having the largest exclusive OR, or a node device having the node identification information having the largest numerical difference as the content holding node device Means,
Content data management apparatus, comprising: content retention requesting means for making a content data retention request to the content retention node apparatus determined by the content retention node apparatus determination means. The content holding node device determining means includes
When determining a plurality of content holding node devices when determining, as the content holding node device, a node device having identification information in which the first digit information is different from the identification information of the content data to be held, The content data management apparatus according to claim 2, wherein a node device having identification information different in the first first digit is determined as the content data holding node device. The content holding node device determining means includes
4. When the number of the content holding node devices to be determined is equal to or greater than the number of the upper first digit, the content holding node devices equal to or greater than the number of the upper first digit are randomly determined. The content data management device described in 1. A plurality of node devices connected to each other via a network, and a content holding node device for storing content data to be shared among the plurality of node devices, a part of the plurality of node devices. A content data management device for storing the content data in the part of the node devices,
The plurality of node devices are node identification information for identifying the plurality of node devices, and the node identification information composed of a predetermined number of digits is given,
The content data distributed in the content distribution system is provided with content identification information configured with a predetermined number of digits and identifying the content data,
A root node device that stores location information indicating the location in the network of the content holding node device that holds the content data is determined for each content data,
A node device to which the node identification information having a difference between the content data held by the content holding node device and the content identification information is within a predetermined range is determined as the root node device;
At least one node device of the plurality of node devices transmits a message transmitted from the content holding node device to the root node device, the message including the location information of the content holding node that has transmitted the message. when receiving, the node device receiving the message, the message, along with transfers to at least one node device of said plurality of node devices, to have contact to the content distribution system that stores the location information in which the received message contains ,
In the content data management device,
Content identification information for identifying the content data distributed in the content distribution system, the content data identification information determining step for determining the content identification information composed of a predetermined number of digits;
A content holding node device for holding content data stored in a content data storage means for storing the content data, wherein the node is different from the content identification information of the content data to be held in the first digit information A node device having identification information, a node device having the node identification information having the largest exclusive OR, or a node device having the node identification information having the largest numerical difference is determined as the content holding node device. A content holding node device determination step;
A content holding request step for making a content data holding request to the content holding node device determined by the content holding node device determination step;
A program for running A plurality of node devices connected to each other via a network, and a content holding node device for storing content data to be shared among the plurality of node devices, a part of the plurality of node devices. A content data management device for storing the content data in the part of the node devices,
The plurality of node devices are node identification information for identifying the plurality of node devices, and the node identification information composed of a predetermined number of digits is given,
The content data distributed in the content distribution system is provided with content identification information configured with a predetermined number of digits and identifying the content data,
A root node device that stores location information indicating the location in the network of the content holding node device that holds the content data is determined for each content data,
A node device to which the node identification information having a difference between the content data held by the content holding node device and the content identification information is within a predetermined range is determined as the root node device;
A message transmitted from the content holding node device to the root node device,
When at least one node device of the plurality of node devices receives a message including the location information of the content holding node that transmitted the message, the node device that has received the message transmits the message to the plurality of node devices. An information processing method in a content distribution system for storing the location information included in the received message and transferring to at least one node device
The content data management device includes:
Content identification information for identifying the content data distributed in the content distribution system, the content data identification information determining step for determining the content identification information composed of a predetermined number of digits;
A content holding node device for holding content data stored in a content data storage means for storing the content data, wherein the node is different from the content identification information of the content data to be held in the first digit information A node device having identification information, a node device having the node identification information having the largest exclusive OR, or a node device having the node identification information having the largest numerical difference is determined as the content holding node device. A content holding node device determination step;
A content holding request step for making a content data holding request to the content holding node device determined by the content holding node device determination step,
The node device is
A receiving step for receiving the holding request;
A content data storing step of storing content data corresponding to the content data holding request in content data storing means when the holding request is received by the receiving means;
Registration message transmission for transmitting a registration message including the location information of the node device storing the content data to the root node device of the stored content data when content data is stored in the content data storage means And an information processing method for a content distribution system.

Images