JP2006197400A - Information distribution system, information update program, information update method or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently manage and update information indicating whether content distribution is possible or not, survival conditions of content node devices, etc. <P>SOLUTION: In an information distribution system, a first node device has a discrimination information transmission means which transmits peculiar discrimination information in order to request a second node device to transmit node information showing an information storage node device having specific common information stored therein, and the second node device includes; a means for storing discrimination information and node information showing an information storage node device wherein common information corresponding to the discrimination information is stored, while they are associated with each other; a means for retrieving node information corresponding to received discrimination information when receiving a request for specific common information from one of a plurality of node devices; a means for transferring the discrimination information to the information storage node device in the case that node information corresponding to the discrimination information is stored in the storage means; a means for judging whether transmission of the specific common information from the information storage node device is possible or not; and a means for updating information stored in the storage means in the case that the transmission is impossible. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a peer-to-peer (P2P) type content distribution system including a plurality of node devices connected to each other via a network, and in particular, distributed from one node device to another node device. The present invention relates to a technical field such as a content distribution system and method in which content data to be stored is distributed and stored in a plurality of node devices.

  In this type of content distribution system, each node device stores information relating to content data distributed and stored in a plurality of node devices (for example, content data attribute information (content name, etc.) and content data. The IP address of the node device) is described, and content data desired by the user can be downloaded based on the information described in the list. Such a list is shared information that should be commonly used in a plurality of node devices, and is generally managed by a management server that manages all content data stored on the content distribution system. The list is distributed to each node device.

For example, Patent Document 1 discloses an index server that exists at the highest level as this type of management server and manages all content information in the content distribution management system.
JP 2002-318720 A

As disclosed in Patent Document 2, pure P2P type distribution systems such as Gnutella, Freenet, Winny, etc. have been devised as methods that do not use a management server. It is structured to search for content by specifying identification information about the content and to identify the location and access it. In such a system, terminals communicate with each other to search and transfer content.
JP 2004-185263 A

  By the way, in a peer-to-peer type content distribution system, a node device is frequently withdrawn (by power failure or failure of the node device, partial network disconnection, etc.) and joined, and the content data node device As the frequency of new savings or deletions to the site increases, the list must be updated frequently as described above, and therefore, as described above, to keep the list up-to-date. Management server is considered necessary.

  However, in the content distribution system in which the management server manages the list, as the number of node devices increases, for example, the server load increases when the list is updated, and the network load can be concentrated and distributed in one place. This causes a problem that the list is limited, which is not preferable. There is also a problem that if the management server is down (for example, due to a failure or the like), the list cannot be updated. Furthermore, there is a problem that the management cost for list management by the management server is also required. Here, “down” indicates that the apparatus is turned off.

  Even if the method does not use the management server, the content node device that holds the content is not always in an operating state. Therefore, in order to grasp the state when the device is down Maintenance must be performed. However, if the content becomes enormous and the number of devices participating in the content distribution system becomes enormous, a large amount of communication for maintenance will be performed between the devices, resulting in a great load on the entire system. There was a problem that. Therefore, there has been a demand for a method for managing and updating content distribution availability information and the content node device survival status with high efficiency. Here, the “survival status” is a status such as whether or not the apparatus is powered on.

  The present invention has been made in view of the above problems and the like, and an information distribution system, an information update program capable of efficiently managing / updating content distribution availability information, the life status of a content node device, and the like, It is an object to provide an information update method and the like.

  In order to solve the above-described problem, the invention according to claim 1 is an information distribution system including a plurality of node devices that are connected to each other by constructing a network, and the first node included in the plurality of node devices. The device is a node device included in the plurality of node devices with respect to a second node device included in the plurality of node devices, and is specified among shared information to be shared among the plurality of node devices. Identification information transmitting means for transmitting unique identification information corresponding to the specific shared information in order to request transmission of node information indicating an information storage node device that stores the specific shared information that is the shared information of The node device 2 stores the identification information in association with the node information indicating the information storage node device that stores the shared information corresponding to the identification information. And when the identification information is received from any one of the plurality of node devices and a request for the specific shared information is received, the received identification information is referred to the storage means. A node information search means for searching for the corresponding node information; and, as a result of the search, if there is node information corresponding to the identification information in the storage means, for the information storage node device indicated by the node information Identification information transfer means for transferring the identification information, determination means for determining whether the information storage node device can transmit the specific shared information, and as a result of the determination, the information storage node device And updating means for updating information stored in the storage means when it is determined that transmission is impossible.

  According to this, when a request for transmission of content as shared information is made from the request node as the first node device, it is based on the distribution availability information, the survival status of the content node as the information storage node device, etc. Since the root node and the cache node as the second node device can update the index information, it is possible to update according to the access frequency, and it is possible to efficiently manage and update the index information.

  In order to solve the above-mentioned problem, the invention according to claim 2 has a time measuring means for starting time measurement when transferring the identification information in the information distribution system according to claim 1, The determination unit has received a failure information indicating that the specific storage information cannot be transmitted from the information storage node device when there is no response from the information storage node device within a predetermined response waiting time. In this case, it is determined that the specific shared information cannot be transmitted by the information storage node device.

  According to this, it becomes possible to quickly manage and update the index information according to the survival status of the content node such as the content node as the information storage node device being powered off.

  In order to solve the above-mentioned problem, the invention according to claim 3 is the information distribution system according to claim 1 or 2, wherein the second node device determines the information as a result of the determination by the determination means. When it is determined that the specific shared information cannot be transmitted by the storage node device, the storage node device has an error reply means for replying to the first node device that there is no specific shared information.

  According to this, it becomes possible for the request node to obtain the latest information regarding whether or not the desired content data can be distributed.

  In order to solve the above-mentioned problem, the invention according to claim 4 is the information distribution system according to any one of claims 1 to 3, wherein the second node device is information by the updating means. Is updated, the other node devices included in the plurality of node devices, the node indicating the identification information corresponding to the specific shared information and the information storage node device storing the specific shared information Update instruction information transmitting means for transmitting update instruction information for instructing update to the other node device having the storage means for storing information.

  According to this, management information of content data can be quickly shared.

  In order to solve the above-mentioned problem, according to a fifth aspect of the present invention, in the information distribution system according to the fourth aspect, the update means receives the update instruction information from any one of the plurality of node devices. When received, the information stored in the storage means is updated according to the update instruction information.

  According to this, since it becomes possible to manage and update its own index information based on update instruction information from other node devices, it is possible to quickly share content data management information between systems. .

  In order to solve the above-described problem, the invention according to claim 6 includes a first configuration included in the plurality of node devices constituting an information distribution system including a plurality of node devices connected to each other by constructing a network. The plurality of nodes receiving a request for transmission of node information relating to at least one or more information storage node devices that store specific shared information that is specific shared information among shared information to be shared among the plurality of node devices. In the second node device included in the node device, the unique identification information corresponding to the shared information and the node information indicating the information storage node device storing the shared information corresponding to the identification information, respectively Storage means for storing the information in association with each other, and receiving the identification information from any one of the plurality of node devices to obtain the information on the specific shared information. The node information search means for searching the node information corresponding to the received identification information with reference to the storage means, and the node corresponding to the identification information in the storage means as a result of the search If there is information, identification information transfer means for transferring the identification information to the information storage node device indicated by the node information, and whether the information storage node device can transmit the specific shared information A determination unit; and an update unit that updates the information stored in the storage unit when it is determined that transmission of the specific shared information by the information storage node device is impossible as a result of the determination. And

  In order to solve the above-mentioned problem, the invention according to claim 7 is the second node device according to claim 6, further comprising time measuring means for starting time measurement when the identification information is transferred. And the determination means includes the information indicating that the specific storage information cannot be transmitted from the information storage node device when there is no response from the information storage node device within a predetermined response waiting time. When received, the information storage node device determines that the specific shared information cannot be transmitted.

  In order to solve the above-mentioned problem, the invention according to claim 8 is the second node device according to claim 6 or claim 7, wherein the identification by the information storage node device as a result of the determination by the determination means. When it is determined that transmission of shared information is not possible, there is provided an error reply means for replying to the first node device that there is no specific shared information.

  In order to solve the above-described problem, the invention according to claim 9 is the second node device according to any one of claims 6 to 8, wherein information is updated by the updating means. The other node devices included in the plurality of node devices, wherein the identification information corresponding to the specific shared information and the node information indicating the information storage node device storing the specific shared information are stored. Update instruction information transmitting means for transmitting update instruction information for instructing update to the other node device having storage means is provided.

  In order to solve the above-mentioned problem, the invention according to claim 10 is the second node device according to claim 9, wherein the update unit is configured to instruct the update from any one of the plurality of node devices. When the information is received, the information stored in the storage unit is updated according to the update instruction information.

  In order to solve the above-described problem, the invention according to claim 11 is the first node included in the plurality of node devices constituting an information distribution system including a plurality of node devices connected to each other by constructing a network. The plurality of nodes receiving a request for transmission of node information relating to at least one or more information storage node devices that store specific shared information that is specific shared information among shared information to be shared among the plurality of node devices. The node information indicating the information storage node device that stores the unique identification information corresponding to the shared information and the shared information corresponding to the identification information for the computer included in the second node device included in the node device And a storage means for storing the information in association with each other, receiving the identification information from any one of the plurality of node devices, and When a request for fixed shared information is received, node information search means for searching the node information corresponding to the received identification information with reference to the storage means, and as a result of the search, the identification in the storage means If there is node information corresponding to the information, identification information transfer means for transferring the identification information to the information storage node device indicated by the node information, transmission of the specific shared information by the information storage node device A determination unit for determining whether or not the information storage node device is capable of transmitting the specific shared information as a result of the determination; and functioning as an update unit for updating information stored in the storage unit. It is characterized by that.

  In order to solve the above-mentioned problem, the invention according to claim 12 is the information update program according to claim 11, wherein the computer starts time measurement when transferring the identification information. And when the response is not received from the information storage node device within a predetermined response waiting time, or the specific shared information cannot be transmitted from the information storage node device. The information storage node device functions so as to determine that transmission of the specific shared information is impossible.

  In order to solve the above-mentioned problem, the invention according to claim 13 is the information update program according to claim 11 or 12, wherein the information storage node device uses the computer as a result of determination by the determination means. When it is determined that transmission of the specific shared information is impossible, the first node device is caused to function as an error reply unit that replies that there is no specific shared information.

  In order to solve the above-described problem, an invention according to claim 14 is the information update program according to any one of claims 11 to 13, wherein the information is updated by the update means in the computer. And storing the identification information corresponding to the specific shared information and the node information indicating the information storage node device that stores the specific shared information. It is made to function as an update instruction information transmission means which transmits the update instruction information which instruct | indicates update with respect to the said other node apparatus which has the said memory | storage means to perform.

  In order to solve the above-mentioned problem, the invention according to claim 15 is the information update program according to claim 14, wherein the update means receives the update instruction information from any one of the plurality of node devices. When received, the information stored in the storage means is updated according to the update instruction information.

  In order to solve the above problem, the invention described in claim 16 is characterized in that the information update program described in any one of claims 11 to 15 is recorded in a computer-readable manner.

  In order to solve the above-mentioned problem, an invention according to claim 17 is included in the plurality of node devices in an information updating method in an information distribution system including a plurality of node devices connected to each other by constructing a network. A first node device is a node device included in the plurality of node devices with respect to a second node device included in the plurality of node devices, and is to be shared among the plurality of node devices An identification information transmitting step for transmitting unique identification information corresponding to the specific shared information in order to request transmission of node information indicating an information storage node device that stores the specific shared information that is specific shared information among the information; The second node device includes the identification information and the node information indicating the information storage node device that stores the shared information corresponding to the identification information. When the second node device receives the identification information from the node device of any of the plurality of node devices and receives the request for the specific shared information, A node information search step for searching the node information corresponding to the received identification information from the information stored in the storage step, and information stored in the storage step by the second node device as a result of the search If there is node information corresponding to the identification information, the identification information transfer step of transferring the identification information to the information storage node device indicated by the node information, and the second node device A determination step of determining whether or not the specific shared information can be transmitted by the information storage node device; and the second node device determines, as a result of the determination, the information storage node device When the transmission of the constant sharing information is determined impossible is characterized by having, an update step of updating the stored information in said storing step.

  In order to solve the above-mentioned problem, the invention described in claim 18 is the information update method according to claim 17, wherein the second node device starts measuring time when transferring the identification information. A time measurement step, and the determination step is a case where there is no response from the information storage node device within a predetermined response waiting time, or the specific storage information cannot be transmitted from the information storage node device. When the information indicating that there is certain information is received, it is determined that the specific shared information cannot be transmitted by the information storage node device.

  In order to solve the above-described problem, the invention described in claim 19 is the information update method according to claim 17 or 18, wherein the second node device determines the information as a result of the determination in the determination step. In the case where it is determined that the specific shared information cannot be transmitted by the storage node device, an error reply process is provided for replying to the first node device that there is no specific shared information.

  In order to solve the above-mentioned problem, an invention according to claim 20 is the information update method according to any one of claims 17 to 19, wherein the second node device performs information by the update step. Is updated, the other node devices included in the plurality of node devices, the node indicating the identification information corresponding to the specific shared information and the information storage node device storing the specific shared information An update instruction information transmission step of transmitting update instruction information for instructing update to the other node device having the storage step of storing information.

  In order to solve the above-mentioned problem, the invention according to claim 21 is the information update method according to claim 20, wherein the update instruction information is received from any one of the plurality of node devices in the update step. When received, the information stored in the storing step is updated according to the update instruction information.

  According to the present invention, it is possible to efficiently manage and update content distribution availability information, the life status of content node devices, and the like.

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

[1. Content distribution system configuration]
First, with reference to FIG. 1, a schematic configuration and the like of a content distribution system as an information distribution system will be described.

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

  As shown in the lower frame 101 of FIG. 1, IX (Internet eXchange) 3, ISP (Internet Service Provider) 4, DSL (Digital Subscriber Line) line operator (device) 5, FTTH (Fiber To The Home) line 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.

  The content distribution system S is configured to include a plurality of node devices 1a, 1b, 1c,... 1x, 1y, 1z,. Network system. Each node device 1a, 1b, 1c... 1x, 1y, 1z... Is assigned a unique manufacturing number and IP (Internet Protocol) address as information (node 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]
Hereinafter, an algorithm using a distributed hash table (hereinafter referred to as DHT (Distributed Hash Table)) according to the present embodiment will be described.

  In the content distribution system S described above, when the node devices 1 exchange information with each other, they must know the IP address as the node 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. Further, when the power of any node device is 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, in one node device 1, only the minimum necessary IP address of the node device 1 among all the node devices 1 participating in the network 8 is remembered (stored), and the IP address is set. For node devices 1 that are not known (not stored), a system has been devised in which information is transferred between the node devices 1 and sent to each other.

  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 using the existing network 8.

  In the present embodiment, an overlay network 9 constructed by an algorithm using DHT is assumed, and a 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.

  The node ID of each node device 1 participating in the content distribution system S is given a unique number for each node device. This number needs to have a number of bits that can accommodate the maximum number of nodes that can be operated. For example, if the number is 128 bits, 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 such as the IP address or serial number of each node device using a common hash function (hash algorithm). It is a hash value and is distributed and distributed in one ID space without deviation. Thus, the node ID obtained (hashed) by the common hash function has a very low probability of having the same value if the IP address or the manufacturing number is different. 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.

  In addition, content (for example, movies, music, etc.) data as shared information distributed from one node device 1 to another node device 1 is distributed to a plurality of node devices 1 participating in the content distribution system S. However, a unique (unique) number (hereinafter referred to as a content ID) is assigned to each content data.

  The content ID has the same length as the node ID (for example, 128 bits). For example, when a keyword such as a content name (content title) or content outline information (synopsis) obtains the node ID. And the node ID that is hashed by a common hash function (that is, placed in the same ID space as the hash value of the IP address of the node device 1) and closest to the hash value (for example, the higher-order digits match more). The node device 1 having the content data stores the link data (IP address of the content storage node) to the node device that stores the content data. As a result, the content data can be distributed on the content distribution system S without any bias. 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).

  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 with 32 bits. In the figure, a black dot indicates a node ID, a black diamond indicates a content ID, and the ID increases counterclockwise.

  Next, which content data is stored in which node device 1 is determined under a certain rule. In the present embodiment, the rule is that “a node device 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. It is only necessary to be consistent when allocating. In the example shown in the figure, based on this definition, the content IDa is managed by the node device having the node IDa, the content IDb is managed by the node device having the node IDb, and the content IDc is the node having the node IDc. Managed by the device 1.

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

[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, here, four divisions are used, and ID is represented by a quaternary number having a bit length of 16 bits. An example in which the node ID of the node device 1N is “10230210” and the routing table of the node device 1N is created will be described.

(Level 1 routing)
First, if the ID space is divided into four areas, each area is expressed in four numbers with different maximum digits “0XXXXXXX”, “1XXXXXXX”, “2XXXXXXX”, “3XXXXXXX” (where X is a natural number from 0 to 3, The same). Since the node ID of the node device 1N itself is “10230210”, the node device 1N exists in the area “1XXXXXXX” in the lower left in the figure. Then, the node device 1N appropriately selects the node device 1 existing in an area other than the area where the node device exists (that is, the “1XXXXXXX” area), and stores the IP address of the node ID in the level 1 table. . FIG. 4A shows an example of a level 1 table. Since the second column 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 where the user exists is further divided into four, and four areas “10XXXXXX”, “11XXXXXX”, “12XXXXXX”, “13XXXXXX” ". Then, similarly to the above, the node device 1 existing in an area other than the area in which it exists is appropriately selected, and the IP address of the node ID is stored in the level 2 table. FIG. 4B is an example of a level 2 table. Since the first column indicates the node device 1N itself, it is not necessary to store the IP address.

(Level 3 routing)
Further, as shown in FIG. 3C, among the areas divided into four by the above routing, the area where the user exists is further divided into four, and further four areas “100XXXXX”, “101XXXXX”, “102XXXXX”, “103XXXXX” And divide. Then, similarly to the above, the node device 1 existing in an area other than the area where it exists is appropriately selected, and the IP address of the node ID is stored in the level 1 table. FIG. 4C is an example of a level 3 table. Since the third column shows the node device 1N itself, it is not necessary to store the IP address, and the second column and the fourth column are blank because there is no node device in the area.

  In this way, all the 16-bit IDs can be covered by creating the 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.

[1-3. Content data search method]
Next, an example of a search method for the node device 1 that is a storage source of 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 that is a storage source of content data is searched by DHT.

  Here, a procedure when the node device 1-1 having the node ID “12003030” (hereinafter referred to as “request node”) searches for content data having the content ID “31330012” will be described.

  The request node refers to the level 1 table of the routing table held by itself, and requests content inquiry information (hereinafter, “content inquiry information”) from a node device having a node ID in the same area as the content ID “31330012”. "Is called" query "). That is, since the content ID “31330012” is an area of “3XXXXXXX”, the node device 1 belonging to the area of “3XXXXXXX” knows the IP address (that is, the IP address is stored in the routing table held by itself). A query is transmitted to the node device 1-2 (which stores the address).

  According to the example shown in FIG. 5, since the IP address of the node device 1-2 having the node ID “30100000” is stored in the routing table of the request node, the request node has the node ID “30100000”. A query is transmitted to the node device 1-2.

  Next, the node device 1-2 that has received the query refers to the level 2 table of the routing table held by the node device 1-2 itself, and the node device 1-2 belongs to the area “31XXXXXX”. The query is transferred to the node device 1-3 (node ID “31012001”) that knows the IP address.

  As described above, when the transfer of the query proceeds in the manner of adapting the digit of the content ID from the top and finally reaches the node device 1-5 that manages the content data, that is, the root node, the root node Searches the content ID “31330012” included in the query from the index information managed by itself, and returns the IP address and the like of the node device 1 that owns the content data to the request node. It has become.

  Thus, the request node (node device 1-1) receives the location of the content data with the content ID “31330012”, that is, the IP address of the node device 1 that is the storage source, from the root node (node device 1-5). The content data is acquired (downloaded) from the node device 1 that is the storage source.

[1-4. How to register content data]
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 seen by other node devices on the content distribution system S will be described. This node device 1 becomes a content node as an information storage node device that holds (stores) content.

  The content node obtains a content ID from the content title and the like, and transmits a public message to a node device having the same node ID as the content ID (whether or not this node device actually exists at this point). To do. Then, the public message is also transferred one after another according to the routing table in the same manner as the above query, and when the node message 1 is transferred to the node device 1 having the node ID closest to the content ID included in the public message, the node device 1 determines that there is no other destination node device, it determines that the node device 1 itself should be the root node of the content, and the content ID, auxiliary information (attribute information such as title and genre, , Copyright information such as a director name) and the IP address of the content node are stored as index information.

  Furthermore, in the present embodiment, a node device in the middle of the route to the root node is provided with a cache node that holds index information stored in the root node as a cache. Thereby, before the root node receives the query, the cache node may return the IP address of the content node to the request node that inquired about the location of the content when the query is transferred to the cache node device earlier. It becomes possible.

[2. Node device configuration]
Next, the configuration and function of the node device 1 will be described with reference to FIG. Each node device 1 is a request node as a first node device that inquires about the location of content by a process performed by each node device, and a cache node as a second node device that receives a query from the request node or a terminal on a route. The second node device that manages the content, the root node as the management node device, and the content node as the information storage node device that holds the content as the specific shared information to be inquired by the request node However, the configuration is the same.

  FIG. 6 is a diagram illustrating a schematic configuration example of the node device 1.

  As shown in FIG. 6, each node device 1 includes a control unit 11 as a computer including a CPU having a calculation function, a working RAM, a ROM for storing various data and programs, the content data, and the index. The storage unit 12 (the content data may be stored in the node device 1 that is not stored) is received as a storage unit composed of an HDD or the like for storing (storing) information, the DHT, the program, and the like. A buffer memory 13 for temporarily storing content data; a decoder unit 14 for decoding (data expansion, decoding, etc.) encoded video data (video information) and audio data (audio information) included in the content data; Predetermined drawing processing is applied to the decoded video data, etc. A video processing unit 15 that outputs the video signal, a display unit 16 such as a CRT or a liquid crystal display that displays video based on the video signal output from the video processing unit 15, and D (Digital ) / A (Analog) converted and then amplified and output by an amplifier, a speaker 18 that outputs an audio signal output from the audio processor 17 as a sound wave, and other nodes through the network 8 A communication unit 20 for controlling communication of information with the apparatus 1 and an input unit (for example, a keyboard, a mouse, or the like) that receives an instruction from the user and gives an instruction signal corresponding to the instruction to the control unit 11 , An operation panel, etc.) 21, a control unit 11, a storage unit 12, a buffer memory 13, and a decoder unit 14. Fine communication unit 20 are connected to each other via a bus 22.

  Then, the CPU in the control unit 11 executes various programs stored in the storage unit 12 and the like, so that the request node as the first node device, the cache node as the second node device, the second node device, The node device 1 as a whole is controlled as a root node as a management node device and a content node as an information storage node device.

  When the node device 1 functions as a request node, the control unit 11 functions as an identification information transmission unit. When the node device 1 functions as a cache node or a root node, the control unit 11 Functions as storage means, node information search means, identification information transfer means, determination means, update means, error response means, and update instruction information transmission means.

[3. Operation of content distribution system]
Next, the operation of the content distribution system S will be described with reference to FIGS.

[3-1. Operation of the entire content distribution system]
First, the operation of the entire content distribution system will be described with an example.

  FIG. 7 is an explanatory diagram showing the exchange of various information such as queries between a request node, a cache node, and a content node when a request node makes a content distribution request (in this figure, an intermediate node and Is a node that does not have a valid index cache for the content of interest, and a cache node is a node that has it.)

  FIG. 8 is a sequence chart between a request node, a content node, a root node, an intermediate node on a route, and a cache node when the request node confirms the location of a content node holding desired content data. FIG. 8A is a sequence chart when content can be distributed to content nodes, and FIG. 8B is a case where content does not exist to be distributed to content nodes. Or, it is a sequence chart when the content node itself is not operating for some reason (when the power is turned off, etc.).

  In the present embodiment, whether or not there is a content node existence confirmation or content can be distributed to the content node, triggered by the transmission of the content data location inquiry (query) from the request node When it is confirmed that the content cannot be distributed, the cache node or the root node updates the list of index information held by itself.

  First, a case where a content node is found in a cache node when content is effectively present in the content node will be described with reference to FIGS. 7 and 8A.

  First, when the request node transmits a query to an intermediate node, the intermediate node that has received the query searches the content ID included in the query from the index information managed by itself, and determines that there is no content ID. Further, the query is transferred to a node device closer to the root node. According to the example shown in FIG. 7, the query is transferred to the cache node.

  Subsequently, in the cache node that has received this, similarly to the above, the content ID included in the query is searched from the index information managed by itself, and here, the search is successful. Forward the query. FIG. 9 shows an example of index information stored in the storage unit 12 of the cache node.

  Then, after receiving the distributable information indicating that the content node can distribute the content data to the request node from the content node, the cache node transmits the IP address of the content node to the request node. According to the example shown in FIG. 9, when the content ID as identification information included in the query is “30001012”, the IP address “121.43.154.65” as the node information of the content node corresponding to this is searched. The IP address is returned to the request node as IP address information.

  Thus, the request node receives the IP address information of the content node from the cache node, thereby knowing the location of the desired content data, that is, the existence of the content node that is the storage source, and accessing the content node. Then, the content data is acquired (downloaded).

  Next, a case where a content node is found in a cache node with reference to FIG. 8B but no content exists in the content node or the content node itself is not operating for some reason will be described. .

  First, when the request node transmits a query to the intermediate node as described above, the intermediate node that has received the query determines that the content ID included in the query is not searched from the index information managed by itself. After that, the query is transferred to a node device closer to the root node. According to the example shown in FIG. 7, the query is transferred to the cache node.

  Subsequently, the cache node that has received this also searches the content ID included in the query from the index information managed by itself in the same manner as described above. Forward the query.

  At this point, the cache node starts measuring time, and if the response from the content node is not within the predetermined response waiting time (timeout), or that the content data cannot be delivered to the request node. When the undeliverable information is received from the content node, the index information stored in the storage unit 12 of the cache node is updated. Specifically, when the content ID included in the query is “30001012”, information related to the content (auxiliary information such as the IP address “121.43.154.65” of the content node and the title “O! ★”) is displayed. Delete from index information.

  Then, the cache node transmits information instructing to delete the information having the content ID “30001012” toward the root node as update instruction information. In this way, the root node or another cache node between the root node and the cache node (although another cache node is not written in FIG. 7) can be changed based on the received update instruction information. Information related to the content with the content ID “30001012” is deleted from the index information stored in the storage unit 12 to update the index information. On the other hand, the cache node transmits an error response indicating that the content node is down to the request node.

[3-2. Operation of each node]
Next, the processing performed in each node when the request node makes a content distribution request will be described in detail. As described above, all the node devices 1 included in the content distribution system S include a request node, a cache, It can be any node device such as a node, a root node, a content node, or a node on a route.

  For example, when the user operates the input unit 21 provided in the node device 1 to instruct the location of the desired content data as the specific shared information, the node device 1 becomes the first node device. Functions as a request node. In addition, the node device 1 that has received a query from the request node and inquired about the location of the content data has a cache node or a root node when the content information is included in the index information stored in its storage unit 12. And also functions as a content node when it holds the content.

  Hereinafter, processing performed in the node device 1 when functioning as each node will be described in detail with reference to FIGS. 10 and 11.

[3-2-1. Request node processing]
First, the processing of the request node will be described with reference to FIG. FIG. 10 is a flowchart showing processing performed when the program stored in the control unit 11 of the request node is executed by the control unit 11.

  When the user inputs a content title or the like by operating the input unit 21 and an inquiry about the location of desired content data is made, the content ID (specification) indicating the content data by hashing the content title or the like is hashed. (Specific identification information corresponding to the shared information) is generated, and a query including the generated content ID is transmitted to another node device 1 with reference to the routing table stored in the storage unit 12 (step S1). . The selection method of the other node device 1 is based on the method described in detail in the “1-3 Content Data Search Method” described above.

  Next, when the IP address information of the content node is received from the root node or the cache node (step S2: IP address information), a distribution request is made to the content node that is the identification source of the IP address information (step S4). Exit.

  On the other hand, when an error response is received from the root node or the cache node in step S2 (step S2: error response), a predetermined content such as a message such as “The specified content was not found” is displayed on the display unit 16. A node discovery impossible process is performed (step S4), and the process is terminated.

[3-2-2. Processing of cache node and root node]
Next, processing of the cache node and the root node will be described with reference to FIG. FIG. 11 is a flowchart showing processing performed when the information update program stored in the control unit 11 of the cache node or the root node is executed by the control unit 11.

  The processing is started when a query is transmitted from the request node or another node device.

  First, the control unit 11 functions as a node information search unit, refers to the index information stored in its own storage unit 12 based on the content ID included in the received query, and the content node corresponding to the content ID (Node information) is retrieved (step S10).

  Next, it is determined whether or not the content node information corresponding to the content ID has been found (step S11). If not found (step S11: No), whether or not the node is the root node is determined. When the determination is made (step S12) and the node itself is not the root node (step S12: Yes), the query is transferred to the upstream node device (step S13), and the process is terminated.

  On the other hand, if it is determined in step S12 that it is the root node (step S12: No), an error response is transmitted to the request node (step S14). Then, the control unit 11 functions as an update instruction information transmission unit, and updates the content information indicated by the content ID included in the query (content node IP address and update instruction information for deleting index information such as various auxiliary information). Transmission is performed to all cache nodes in the content distribution system S (step S15), and the process is terminated.

  Further, in the process of step S11, when the information of the content node corresponding to the content ID is found (step S11: Yes), the control unit 11 functions as identification information transfer means, and transfers a query to the content node. (Step S16).

  Subsequently, the control unit 11 functions as a time measuring unit, and starts time measurement using a built-in clock or the like provided in the apparatus (step S17).

  Thereafter, when some information is received from the content node (step S18), if the received information is distributable information (step S18: distributable information), IP address information indicating the IP address of the content node is obtained. The request is transmitted to the request node (step S19), and the process is terminated.

  On the other hand, when the information received in step S18 is undeliverable information (step S18: undeliverable information), the process proceeds to step S21, and when information regarding the possibility of distribution is not received in step S18 (step S18). (S18: No reception), the process proceeds to step S20.

  In step S20, it is determined whether or not a predetermined response waiting time (for example, 10 seconds) has elapsed. If it has elapsed (step S20: Yes), the process proceeds to step S21. If not (step S20: Yes), the process proceeds to step S18 to wait for reception of information.

  That is, in step S18 and step S20, the control unit 11 functions as a determination unit.

  Subsequently, when the non-delivery information is received in step S18, or when there is no response from the content node even after the response waiting time has elapsed (timeout, step S20: Yes), the control unit 11 updates the update unit. The index information stored in the storage unit 12 is updated (step S21). More specifically, the content information (content node IP address, various auxiliary information, etc.) indicated by the content ID included in the query is deleted.

  Next, the control unit 11 functions as an error reply unit, and transmits an error reply to the request node (step S22).

  Next, it is determined whether or not it is the root node (step S23). If it is not the root node (step S23: No), it functions as an update instruction information transmission unit and instructs to update the index information. The update instruction information to the effect is transmitted to the upstream node device (step S24) (that is, transmitted in the direction of the root node), and the process ends. On the other hand, when it is a root node (step S23: Yes), it functions as an update instruction information transmission means, and transmits the update instruction information to all the cache nodes in the content distribution system S (step S25). To finish the process.

  Actually, since the downstream cache node always confirms the existence status of the content node first, the root node first knows that the index information held by the lower level cache node is invalid (the existence status of the content node). It is considered that there are not many cases. However, for example, when the root node itself becomes a request node for inquiring about the location of the content node at another timing, the root node may first know the survival status of the content node. In such a case, the root node issues an update instruction to the cache node. In order for the root node to know the IP address of the downstream cache node, when the content data is registered (refer to “1-4. Content Data Registration Method”), the public message is sent from the content holder to the cache node. In the process of relaying and transferring to the root node, each cache node stores the IP address of the message transmission source (stores the reverse link of the spanning tree shown in FIG. 7).

  Further, when the content node is restored again, the content node transmits a public message to the root node in accordance with the “1-4. Content data registration method” described above, whereby the cache node and the storage unit 12 of the root node are stored. The stored index information is updated (content information is registered).

  As described above, according to the present embodiment, when an inquiry about the location of content data is made from the request node, the cache node and the root node can update the index information held by the cache node and the root node. As the content data has more inquiries (requests) about the location of the data, the root node or cache node that is the management source of the content data can always hold the latest information regarding the content data. For content data with few inquiries (requests) on the location of the content data, the root node and cache node that are the management source of the content data do not need to frequently manage and update the survival information about the content data. In addition, management / update according to the access frequency of the content becomes possible, for example, the update cost of the index information can be reduced.

  Further, the present invention can also be applied when there are a plurality of content nodes having arbitrary content in the content distribution system S.

  Furthermore, when either the root node or the cache node that manages the content data recognizes that the content node that holds the content data is down or that the content data cannot be distributed, not only updates its own index information but also other routes. Since the update instruction information for instructing the update is transmitted to the node or the cache node, the content data management information can be quickly shared.

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. (A) An example of a level 1 table. (B) An example of a level 2 table. (C) An example of a level 3 table. (D) An example of a completed routing table. It is a figure which shows an example of a mode that the node apparatus 1 which is a storage source of content data is searched by DHT. 2 is a diagram illustrating a schematic configuration example of a node device 1. FIG. Explanatory diagram showing the exchange of various information such as queries between request nodes, content nodes, root nodes, and cache nodes in the form of a spanning tree (A) It is a sequence chart when the content exists in the state which can deliver a content node. (B) A sequence chart when the content node does not exist in a state where the content can be distributed, or when the content node itself is not operating for some reason. It is an example of the index information memorize | stored in the memory | storage part 12 of the cache node. It is a flowchart which shows the process in the control part 11 of a request node. It is a flowchart which shows the information update process in the control part 11 of a cache node or a root node.

Explanation of symbols

1 node device 8 network 11 control unit 12 storage unit 13 buffer memory 14 decoder unit 15 video processing unit 16 display unit 17 audio processing unit 18 speaker 20 communication unit 21 input unit 22 bus S content distribution system

Claims (21)

In an information distribution system comprising a plurality of node devices connected to each other by building a network,
The first node device included in the plurality of node devices is:
The second node device included in the plurality of node devices, the node device included in the plurality of node devices, and specific shared information among the shared information to be shared among the plurality of node devices Identification information transmitting means for transmitting unique identification information corresponding to the specific shared information to request transmission of node information indicating an information storage node device that stores the specific shared information.
The second node device is
Storage means for storing the identification information and the node information indicating the information storage node device that stores the shared information corresponding to the identification information in association with each other;
If the identification information is received from any one of the plurality of node devices and the request for the specific shared information is received, the node information corresponding to the received identification information with reference to the storage means Node information search means for searching for,
As a result of the search, when there is node information corresponding to the identification information in the storage means, identification information transfer means for transferring the identification information to the information storage node device indicated by the node information;
Determining means for determining whether or not the specific shared information can be transmitted by the information storage node device;
As a result of the determination, if it is determined that transmission of the specific shared information by the information storage node device is impossible, an update unit that updates information stored in the storage unit;
An information distribution system comprising: The information distribution system according to claim 1,
When transferring the identification information, it has time measuring means for starting measurement of time,
The determination unit has received a failure information indicating that the specific storage information cannot be transmitted from the information storage node device when there is no response from the information storage node device within a predetermined response waiting time. In this case, it is determined that the specific storage information cannot be transmitted by the information storage node device. In the information delivery system according to claim 1 or 2,
When the second node device determines that transmission of the specific shared information by the information storage node device is impossible as a result of the determination by the determining means, the specific shared information is sent to the first node device. An information delivery system comprising an error reply means for replying that there is no data. In the information delivery system according to any one of claims 1 to 3,
When the information is updated by the updating unit, the second node device is another node device included in the plurality of node devices, the identification information corresponding to the specific shared information, and the specific information Update instruction information transmitting means for transmitting update instruction information for instructing update to the other node apparatus having the storage means for storing node information indicating the information storage node apparatus for storing shared information; An information distribution system characterized by The information distribution system according to claim 4,
The update unit updates the information stored in the storage unit according to the update instruction information when the update instruction information is received from any one of the plurality of node devices. Distribution system. Shared information to be shared among the plurality of node devices from the first node device included in the plurality of node devices constituting an information distribution system including a plurality of node devices connected to each other by constructing a network A second node device included in the plurality of node devices that receives a request for transmission of node information relating to at least one or more information storage node devices that store specific shared information that is specific shared information,
Storage means for storing the unique identification information corresponding to the shared information and the node information indicating the information storage node device that stores the shared information corresponding to the identification information in association with each other;
If the identification information is received from any one of the plurality of node devices and the request for the specific shared information is received, the node information corresponding to the received identification information with reference to the storage means Node information search means for searching for,
As a result of the search, when there is node information corresponding to the identification information in the storage means, identification information transfer means for transferring the identification information to the information storage node device indicated by the node information;
Determining means for determining whether or not the specific shared information can be transmitted by the information storage node device;
As a result of the determination, if it is determined that transmission of the specific shared information by the information storage node device is impossible, an update unit that updates information stored in the storage unit;
A second node device comprising: The second node device according to claim 6, wherein
When transferring the identification information, it has time measuring means for starting measurement of time,
The determination unit has received a failure information indicating that the specific storage information cannot be transmitted from the information storage node device when there is no response from the information storage node device within a predetermined response waiting time. In this case, it is determined that the specific storage information cannot be transmitted by the information storage node device. In the second node device according to claim 6 or 7,
As a result of the determination by the determination means, if it is determined that the specific shared information cannot be transmitted by the information storage node device, an error response is returned to the first node device that there is no specific shared information A second node device comprising means. In the 2nd node apparatus as described in any one of Claim 6 thru | or 8,
When the information is updated by the updating means, the information storage is another node device included in the plurality of node devices, and stores the identification information corresponding to the specific shared information and the specific shared information A second node having update instruction information transmitting means for transmitting update instruction information for instructing update to the other node apparatus having the storage means for storing node information indicating a node device; apparatus. The second node device according to claim 9, wherein
The update means updates the information stored in the storage means according to the update instruction information when the update instruction information is received from any one of the plurality of node apparatuses. 2 node devices. Shared information to be shared among the plurality of node devices from the first node device included in the plurality of node devices constituting an information distribution system including a plurality of node devices connected to each other by constructing a network A computer included in a second node device included in the plurality of node devices that receives a request for transmission of node information related to at least one information storage node device that stores specific shared information that is specific shared information,
Storage means for storing the unique identification information corresponding to the shared information and the node information indicating the information storage node device that stores the shared information corresponding to the identification information in association with each other;
If the identification information is received from any one of the plurality of node devices and the request for the specific shared information is received, the node information corresponding to the received identification information with reference to the storage means Node information search means for searching for,
As a result of the search, if there is node information corresponding to the identification information in the storage means, identification information transfer means for transferring the identification information to the information storage node device indicated by the node information;
Determining means for determining whether or not the specific shared information can be transmitted by the information storage node device; and
As a result of the determination, if it is determined that transmission of the specific shared information by the information storage node device is impossible, the information update program is made to function as an update unit that updates information stored in the storage unit . In the information update program according to claim 11,
Causing the computer to function as time measuring means for starting time measurement when transferring the identification information, and the determination means has no response from the information storage node device within a predetermined response waiting time Or when it is determined that the specific storage information cannot be transmitted from the information storage node device, it is determined that the specific storage information cannot be transmitted by the information storage node device. An information update program characterized by functioning. In the information update program according to claim 11 or claim 12,
As a result of the determination by the determination means, if the computer determines that transmission of the specific shared information by the information storage node device is impossible, there is no specific shared information for the first node device. An information update program that functions as an error reply means for replying. In the information update program according to any one of claims 11 to 13,
When the information is updated by the updating means, the computer is another node device included in the plurality of node devices, and stores the identification information corresponding to the specific shared information and the specific shared information An update instruction information transmitting means for transmitting update instruction information for instructing an update to the other node apparatus having the storage means for storing the node information indicating the information storage node device to be performed, Information update program. In the information update program according to claim 14,
When the update means receives the update instruction information from any one of the plurality of node apparatuses, the update means functions to update the information stored in the storage means according to the update instruction information. Information update program.   16. A recording medium in which the information update program according to claim 11 is recorded so as to be readable by a computer. In an information updating method in an information distribution system comprising a plurality of node devices connected to each other by constructing a network,
The first node device included in the plurality of node devices is a node device included in the plurality of node devices with respect to a second node device included in the plurality of node devices, and the plurality of nodes In order to request transmission of node information indicating an information storage node device that stores specific shared information that is specific shared information among shared information to be shared between devices, unique identification information corresponding to the specific shared information is provided. An identification information transmitting step for transmitting;
A storage step in which the second node device stores the identification information in association with the node information indicating the information storage node device that stores the shared information corresponding to the identification information;
When the second node device receives the identification information from any one of the plurality of node devices and receives the request for the specific shared information, the second node device uses the information stored in the storage step to A node information search step of searching for the node information corresponding to the received identification information;
When there is node information corresponding to the identification information in the information stored in the storage step as a result of the search, the second node device performs the information storage node device indicated by the node information. An identification information transfer step of transferring the identification information;
A determining step in which the second node device determines whether or not the specific shared information can be transmitted by the information storage node device;
When the second node device determines that transmission of the specific shared information by the information storage node device is impossible as a result of the determination, an update step of updating the information stored in the storage step;
An information updating method characterized by comprising: The information updating method according to claim 17,
The second node device has a time measurement step of starting time measurement when transferring the identification information;
In the determination step, when there is no response from the information storage node device within a predetermined response waiting time, or when the information storage node device has received unusable information indicating that the specific shared information cannot be transmitted. In this case, it is determined that the specific shared information cannot be transmitted by the information storage node device. In the information update method according to claim 17 or 18,
If the second node device determines that transmission of the specific shared information by the information storage node device is impossible as a result of the determination in the determination step, the specific shared information is sent to the first node device. An information update method characterized by comprising an error reply process for replying that there is no data. The information updating method according to any one of claims 17 to 19,
When the information is updated by the updating step, the second node device is another node device included in the plurality of node devices, the identification information corresponding to the specific shared information, and the specific information An update instruction information transmitting step of transmitting update instruction information for instructing update to the other node device having the storage step of storing node information indicating the information storage node device storing shared information; An information update method characterized by the above. The information updating method according to claim 20,
When the update instruction information is received from any one of the plurality of node devices in the update step, the information stored in the storage step is updated according to the update instruction information. Information update method.

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