JP2006059133A - Information distribution system, node system, location information retrieval method, and location information retrieval processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information distribution system capable of efficiently managing locations of distributably stored contents data and quickly performing retrieval processing even if the number of distributably stored contents data is massive, a node system, a location information retrieval method, and a location information retrieval processing program thereof. <P>SOLUTION: The information distribution system has a plurality of node systems connected with each other via a network, and distributably stores distribution information to be transmitted from one of the node system to the other node system into the plurality of node systems. As for list information respectively existing in a plurality of retrieved information being different from each other, the list information including location information showing locations of distribution information related to the retrieved information is distributably stored in the plurality of node systems. <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 location information indicating the location of content data to be distributed is distributed and stored in a plurality of node devices.

  In this type of content distribution system, index information (location information) including location information (for example, device IDs and IP addresses of node devices) indicating the location of content data distributed and stored in a plurality of node devices by each node device. A list of information) is held, and content data to be acquired (downloaded) is searched based on the index information.

  Such index information is generally managed by a management server that manages all content data stored on the content distribution system, and the index information is distributed from the management server to each node device. Become.

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

  However, in a peer-to-peer type content distribution system, node devices are frequently withdrawn (due to a power failure or failure of the node devices or a partial network disconnection) and participated frequently. In particular, the index information held by each node device must be updated, which is inefficient, and as the number of node devices increases, the server load increases when the index information is updated. There is a problem that the network load is concentrated in one place and index information that can be distributed is limited, which is not preferable. In addition, when the management server is down (for example, due to a failure or the like), there is a problem that the index information cannot be updated.

  In addition, when the number of content data distributed and stored on the content distribution system is enormous, the location information described in the index information held by each node device also becomes enormous. There is a problem that processing takes a very long time and the load on the node device also increases.

  The present invention has been made in view of the above problems and the like, can manage the location of content data stored in a distributed manner more efficiently, and the number of content data stored in a distributed manner can be reduced. It is an object of the present invention to provide an information distribution system, a node device, a location information search method, a location information search processing program, and the like that can perform search processing quickly even when the amount is large.

  In order to solve the above problem, the invention according to claim 1 includes a plurality of node devices connected to each other via a network, and distribution information to be distributed from one node device to another node device is provided. In the information distribution system distributed and stored in the plurality of node devices, the list information exists for each of a plurality of different search information, and includes location information indicating the location of the distribution information related to the search information. The list information is distributed and stored in the plurality of node devices.

  According to the first aspect of the present invention, the list information including the location information indicating the location of the distribution information related to the search information, the list information existing for each of a plurality of different search information, Since it is configured to be distributed and stored in a plurality of node devices, it is not necessary for all node devices to hold common list information, and each node device that stores list information has its own search information. As a root node device, only its own list information can be managed more efficiently. In addition, the location information of all the distribution information is not included in one list information, but only the location information of the distribution information related to one search information is included. The data capacity (size) can be drastically reduced. Therefore, it can sufficiently cope with the case where the usable storage capacity in the node device is limited, and the search time for the location information of the distribution information is drastically reduced. be able to.

  The invention according to claim 2 is the information distribution system according to claim 1, wherein only one list information is stored in one node device, and two or more of the same list information are stored. The node device is not redundantly stored in the node device.

  According to the second aspect of the present invention, the node device storing the list information need only manage its own list information.

  According to a third aspect of the present invention, in the information distribution system according to the first or second aspect, the list information includes identification information closest to unique identification information corresponding to the search information related to the list information. It is stored in the node device.

  According to a fourth aspect of the present invention, in the information delivery system according to the third aspect, the identification information is a hash value obtained by a predetermined hash function.

  According to the invention described in claim 3 or 4, even when the number of pieces of distribution information stored in a distributed manner is enormous, each node device has unique identification information corresponding to the input search information ( For example, the location of the distribution information related to the input search information can be searched more efficiently and quickly simply by sending the hash value) to the information distribution system.

  The invention according to claim 5 is the node device in the information distribution system according to any one of claims 1 to 3, wherein search information receiving means for receiving search information, and the received search information Based on identification information generating means for generating unique identification information corresponding to the search information based on the search information, and at least the generated identification information for the node device storing the list information corresponding to the search information Identification information transmission means for directly or indirectly transmitting information, and at least the location of distribution information related to the search information returned from the node device storing the list information corresponding to the search information. And a location information receiving means for receiving location information to be indicated.

  According to a sixth aspect of the present invention, in the node device according to the fifth aspect, the node device to which the generated identification information is transmitted directly or indirectly is the identification information closest to the generated identification information. It is a node device having

  According to the invention described in claim 5 or 6, even when the number of distribution information stored in a distributed manner is enormous, each node device has unique identification information corresponding to the received search information ( For example, by only directly or indirectly transmitting a hash value) to the node device storing the list information corresponding to the search information, the location of the distribution information related to the search information is You can search more efficiently and quickly.

  The invention according to claim 7 is the node device according to claim 5 or 6, wherein the distribution information related to the search information is stored based on the received location information. It further comprises distribution information acquisition means for specifying a node device and acquiring the distribution information from the specified node device.

  The invention according to claim 8 is the node device according to any one of claims 5 to 7, wherein the search information receiving means includes at least first search information and second search information that are different from each other, and at least the Receiving a search condition in which the first search information and the second search information are used, the identification information generating means generates unique first identification information corresponding to the first search information based on the first search information. The identification information transmitting unit directly transmits at least the generated first identification information and the second search information directly to the node device storing the list information corresponding to the first search information. Or indirectly, the location information receiving means is returned from the node device storing the list information corresponding to any of the accepted search information, at least Receiving the first location information indicating the location of the distribution information related to the first search information and the second location information indicating the location of the distribution information related to the second search information; and the received first location information; It further comprises location information selection means for selecting location information of distribution information satisfying the search condition based on the second location information.

  According to a ninth aspect of the present invention, in the node device according to any one of the fifth to seventh aspects, the search information receiving means includes at least first search information and second search information that are different from each other, and at least the Receiving a search condition in which the first search information and the second search information are used, the identification information generating means generates unique first identification information corresponding to the first search information based on the first search information. Then, the identification information transmitting means transmits at least the generated first identification information, the second search information, and the node device that stores the list information corresponding to the first search information, and The search condition is transmitted directly or indirectly, and the location information receiving means is returned from the node device storing the list information corresponding to any of the accepted search information. And, at least, characterized by receiving the location information indicating the location of the search condition is satisfied delivery information.

  According to the invention described in claim 8 or 9, the location of desired distribution information can be searched more efficiently by using a plurality of search information and search conditions.

  A tenth aspect of the present invention is a node comprising at least identification information receiving means for receiving at least the identification information transmitted directly or indirectly from the node device according to any one of the fifth to seventh aspects. A list information storage means for storing the list information including location information indicating the location of distribution information related to at least one of the search information, and at least the information corresponding to the received identification information Location information acquisition means for acquiring the location information included in list information, and at least location information return means for returning the acquired location information to the node device that has transmitted the identification information. It is characterized by.

  The invention described in claim 11 includes identification information receiving means for receiving at least the first identification information and the second search information transmitted directly or indirectly from the node device according to claim 8. A node information storage means for storing list information including first location information indicating a location of distribution information related to the first search information; and at least the received first identification information Location information acquisition means for acquiring the first location information included in the corresponding list information, and identification information for generating unique second identification information corresponding to the second search information based on the second search information At least the generated second identification information and the acquired first location information are generated with respect to the node device storing the list information corresponding to the second search information. And identification information transmitting means for transmitting indirectly or indirectly, characterized in that it comprises a.

  The invention described in claim 12 includes an identification information receiving means for receiving at least the second identification information and the first location information transmitted directly or indirectly from the node device according to claim 11. A list information storage means for storing list information including second location information indicating the location of distribution information related to the second search information, and at least the received second identification information; Location information acquisition means for acquiring the second location information included in the corresponding list information, and transmitting the first identification information with at least the received first location information and the acquired second location information A location information replying means for replying to the node device.

  The invention described in claim 13 receives at least the first identification information, the second search information, and the search condition transmitted directly or indirectly from the node device according to claim 9. A node device comprising information receiving means, list information storing means for storing list information including first location information indicating the location of distribution information related to the first search information, and at least the received Location information acquisition means for acquiring location information indicating the location of the delivery information satisfying the search conditions based on the list information and the second search information corresponding to the first identification information, and at least the selected location information And a location information return means that returns a response to the node device that has transmitted the first identification information.

  According to the invention described in any one of claims 10 to 13, the list information including the location information indicating the location of the distribution information related to at least one of the search information can be managed more efficiently. it can.

  The invention described in claim 14 is the node device according to any one of claims 5 to 13, wherein the identification information is a hash value obtained by a predetermined hash function.

  The invention according to claim 15 is a location information search method of the node device in the information distribution system according to any one of claims 1 to 3, wherein a step of receiving search information, and the received search A step of generating unique identification information corresponding to the search information based on the information, and at least the generated identification information for the node device storing the list information corresponding to the search information. Directly or indirectly transmitting, and at least location information indicating the location of distribution information related to the search information returned from the node device storing the list information corresponding to the search information And a receiving step.

  A sixteenth aspect of the invention is a node comprising at least identification information receiving means for receiving the identification information transmitted directly or indirectly from the node device according to any one of the fifth to seventh aspects. A location information search method for an apparatus, the step of storing the list information including location information indicating the location of distribution information related to at least one of the search information, and at least corresponding to the received identification information Obtaining the location information included in the list information, and returning at least the obtained location information to the node device that transmitted the identification information. .

  According to a seventeenth aspect of the present invention, there is provided a search information receiving means for receiving search information from the computer included in the node device in the information distribution system according to any one of the first to third aspects, the received search information. Based on the identification information generating means for generating unique identification information corresponding to the search information, at least the generated identification information for the node device storing the list information corresponding to the search information At least the location of the distribution information related to the search information sent back from the node information storing the list information corresponding to the search information It is made to function as a location information receiving means for receiving location information indicating.

  The invention according to claim 18 is a node comprising identification information receiving means for receiving at least the identification information transmitted directly or indirectly from the node device according to any one of claims 5 to 7. A computer included in the apparatus corresponds to at least the received identification information, list information storage means for storing the list information including location information indicating the location of distribution information related to at least one of the search information Functions as location information acquisition means for acquiring the location information included in the list information, and at least location information return means for returning the acquired location information to the node device that transmitted the identification information. It is characterized by making it.

  The invention described in claim 19 is characterized in that the location information search processing program described in claim 17 or 18 is recorded so as to be readable by a computer.

  According to the present invention, list information that exists for each of a plurality of different search information and includes location information indicating the location of distribution information related to the search information is stored in the plurality of node devices. Since it is configured to be distributed and stored, all the node devices do not need to hold common list information, and each node device storing the list information is a root node device of each search information, Only its own list information can be managed more efficiently.

  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,... Connected to each other via such a network 8, and is a peer-to-peer network system. . Each node device 1a, 1b, 1c,... Is assigned a unique device ID and an IP (Internet Protocol) address. The device ID and the IP address correspond to each other on a one-to-one basis, and do not overlap among the plurality of node devices 1. In the content distribution system S, each node device 1 obtains an IP address corresponding to the device ID of the other node device 1 (for example, inquires of the node device 1 that manages the IP address). ) It is possible. In the following description, when any one of the node devices 1a, 1b, 1c... Is shown, it may be referred to as the node device 1 for convenience.

  In this content distribution system S, a specific algorithm, for example, an algorithm using a distributed hash table (hereinafter referred to as DHT (Distribute Hash Table)) described later, as shown in the upper frame 100 of FIG. The overlay network 9 is constructed. 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.

  The device IDs of the respective node devices 1 participating in the content distribution system S are hashed by a common hash function and are distributed in the same name space without being distributed. As described above, the hash value of the device ID obtained (hashed) by the common hash function has a very low probability of being the same value if the device ID is different. Since the hash function is publicly known, detailed description thereof is omitted.

  Also, each node device 1 participating in the content distribution system S holds a DHT. In this DHT, its own device ID and its hash value are registered in association with each other, and the device ID of the other node device 1 that forms a link with itself and its hash value are registered in association with each other. ing. The above contents of the DHT held by each node device 1 may be duplicated (when the same device ID and hash value are registered), but are basically different. It can be said that the device IDs of all the node devices 1 in the distribution system S are allocated and held little by little.

  Such DHT is given when the node apparatus 1 participates in the content distribution system S. Since the DHT generation method is known, detailed description thereof is omitted.

  Furthermore, content data (for example, movies, music, etc.) as distribution information to be distributed from one node device 1 to another node device 1 is stored in a plurality of node devices 1 participating in the content distribution system S. Distributed (stored). For example, content data of a movie whose title is XXX is stored in the node device 1a, while content data of movies whose title is YYY is stored in the node device 1b. Are distributed and stored in a plurality of node devices 1 (however, the same content data may be distributed and stored in a plurality of node devices 1).

  The location of each piece of content data thus distributed and stored can be searched from each node device 1 using a keyword as search information. Keywords for searching content data include, for example, movies, TV programs (drama, sports, variety, etc.), music, and other various genre content names (content titles) and copyright information (for example, performer names) , A director name, an original author name, a singer name, a composer name, or a songwriter name). In addition, in the case of foreign movie content, the wording included in subtitle information (for example, dialogue) can be used as a keyword, and in the case of movie content, the wording included in soundtrack information or the like can be used as a keyword. Furthermore, the genre of the content (movie, television program, music, sports, variety, drama, etc.) can be used as a keyword. Note that what words are set as keywords is not particularly limited. In addition, for example, when the content data is stored in any one of the node devices 1, the keyword related to the content data is extracted and set artificially or automatically. (A plurality of keywords may be set for one content data).

  Index information (one node) as list information including location information (for example, the device ID or IP address of the node device 1 in which the content data is stored) indicating the location of the content data related to such a keyword In some cases, only the location information of the device 1 may be included) and is distributed and stored in the plurality of node devices 1 participating in the content distribution system S. This index information exists for each of a plurality of different keywords. For example, the index information of the keyword “flower” includes content data related to the “flower” (for example, “flower” (Location data included in the name) location information is included (registered). On the other hand, the index information of the keyword “Tokyo” includes location information of content data related to “Tokyo” (for example, content data in which “Tokyo” is included in the name of the content).

  The keywords related to the index information distributed and stored in the plurality of node devices 1 are hashed by a hash function common to the hashed device ID (that is, the same hash value of the device ID of the node device 1). And the hash value (unique identification information corresponding to the node device 1) closest to the hash value (unique identification information corresponding to the keyword) (for example, the higher digit matches more). The index information is stored in a node device (hereinafter referred to as “root node device”) 1 having the above-described information.

  In the present embodiment, only one index information corresponding to one keyword is stored in one node device 1, and the same index information is stored redundantly in two or more node devices 1. Not. That is, the keyword and the node device 1 have a one-to-one correspondence. However, the index information corresponding to a plurality of keywords whose hash values are close (for example, many higher digits match) may be stored in one node device 1.

[2. Node device configuration]
Next, the configuration and function of the node device 1 will be described with reference to FIG.

  FIG. 2 is a diagram illustrating a schematic configuration example of the node device 1.

  As shown in FIG. 2, 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. A storage unit 12 configured by an HDD or the like for storing (storing) information, DHT, programs, and the like (the content data and the index information are not stored in the node device 1), and the received content A buffer memory 13 for temporarily storing 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, and the decoding The video data is processed by performing a predetermined drawing process on the recorded video data. 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 by an amplifier and output, audio processor 17 that outputs the audio signal output from the audio processor 17 as a sound wave, and video included in the content data An encoder 19 that encodes data, audio data, etc. (data compression, encryption, etc.), a communication unit 20 for controlling communication of information with other node devices 1 through the network 8, and an instruction from the user The input unit (for example, a key) that receives an instruction signal corresponding to the instruction to the control unit 11 A control unit 11, a storage unit 12, a buffer memory 13, a decoder unit 14, an encoder unit 19, and a communication unit 20 via a bus 22. Are connected to each other.

  Then, the CPU in the control unit 11 executes various programs stored in the storage unit 12 and the like so as to control the entire node device 1, and according to an instruction signal from the input unit 11. Index information registration processing, content data search processing, and the like are performed. These index information registration processing and content data search processing will be described later.

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

(Index information registration process)
First, the index information registration process will be described with reference to FIG.

  FIG. 3A is a flowchart showing index information registration processing in the control unit 11 of the node device 1 that issues a registration request for index information, and FIG. 3B shows a node device that has received the registration request for index information. 3 is a flowchart showing index information registration processing in one control unit 11. The index information registration process shown in FIGS. 3A and 3B is performed when the control unit 11 executes a location information registration process program stored and saved in the storage unit 12 or the like.

  First, in a certain node device 1, for example, a new content data is stored in a storage unit by receiving a content data storage request from the user via the input unit 21 or a content data storage request from another node device 1. When the data is stored in the memory 12, the process shown in FIG. 3A is started, and the control unit 11 performs a keyword extraction process for extracting a keyword related to the content data (step S1). In the keyword extraction process, for example, as described above, the words included in the content name and copyright information are extracted as keywords from the content data or the data associated therewith. Alternatively, the user may operate the input unit 21 to input a keyword related to the content data (for example, a simple expression of the content).

  Note that the node device 1 in which the content data is stored is not particularly limited. For example, the unique content ID of the content data to be stored is hashed from the device ID. The content data is stored in the node device 1 that hashes with a common hash function and has the hash value closest to the hash value of the content ID (for example, the higher-order digits match more).

  Next, the control unit 11 obtains (generates) a hash value of the keyword by hashing the extracted keyword with a hash function common to the device ID hashed (step S2), and is stored and stored in the storage unit 12 The unique DHT is referred to (step S3), and it is determined whether or not it is the root node device 1 of the keyword (step S4). For example, it is determined whether or not the hash value of its own device ID is closest to the hash value of the keyword (for example, more high-order digits match).

  When it is determined that the self is the root node device of the keyword (step S4: Y), the control unit 11 determines whether the index information corresponding to the keyword is already registered (stored in the storage unit 12 and stored). (Step S5), if registered (step S5: Y), the index information is read from the storage unit 12, and the location information of the content data (for example, device ID or IP address) ) And information such as the content name, copyright information, and classification are registered in the index information (step S6), and the index information is stored and stored in the storage unit 12 as list information storage means. The process ends.

  FIG. 4 is a diagram illustrating an example of a list of location information included in the index information of the keyword “flower”. In the location information list 51 of the index information shown in FIG. 4, the location information of content data related to the keyword “flower” (for example, content data in which “flower” is included in the name of the content) is registered. The location information registered in step S6 is additionally registered in the bottom 51a of the list 51.

  On the other hand, when the index information is not registered (step S5: N), the control unit 11 newly generates index information corresponding to the keyword, and the location information of the content data and the name of the content The copyright information, the classification information, and the like are associated and registered in the new index information (step S7), the index information is stored and stored in the storage unit 12, and the process is terminated. In addition, whenever the content data related to the keyword is stored in another node device 1, the location information of the content data is additionally registered in the index information generated in this way.

  On the other hand, when it is determined in step S4 that the self is not the root node device of the keyword (step S4: N), the control unit 11 determines the keyword, the hash value of the keyword, the location information of the content data, and the A registration request for index information to which information such as a content name, copyright information, and classification is added is issued, and the registration request for the index information is transmitted to another node device 1 via the communication unit 20 or the like (step S8). ), The process ends. For example, among the hash values registered in the DHT, for the node device 1 having a device ID corresponding to the hash value closest to the keyword hash value (for example, the higher digits match more), The index information is transmitted.

  On the other hand, in the node device 1 that has received (received) the registration request for index information, the processing shown in FIG. 3B is started. First, the control unit 11 is stored and saved in the storage unit 12. Referring to the DHT (step S11), it is determined whether or not itself is the root node device 1 of the keyword (step S12). For example, it is determined whether or not the hash value of its own device ID is closest to the hash value of the received keyword (for example, the higher digits match more).

  When it is determined that the self is the root node device of the keyword (step S12: Y), the control unit 11 determines whether the index information corresponding to the keyword is already registered (stored in the storage unit 12 and stored). (Step S13), if registered (step S13: Y), the index information is read from the storage unit 12, the location information of the received content data and the content name, Information such as copyright information and classification is associated and registered in the index information (step S14), the index information is stored and stored in the storage unit 12 as list information storage means, and the process ends.

  On the other hand, when the index information is not registered (step S13: N), the control unit 11 newly generates the index information corresponding to the keyword, and the location information and content of the received content data. Are registered in the new index information (step S15), the index information is stored and stored in the storage unit 12, and the process is terminated.

  On the other hand, when it is determined in step S12 that the self is not the root node device of the keyword (step S12: N), the control unit 11 receives the received keyword, the hash value of the keyword, and the content data. Is sent (transferred) to the other node device 1 (step S16), and the processing is terminated. Also in this case, for example, among the hash values registered in the DHT, the node device 1 having the device ID corresponding to the hash value closest to the keyword hash value (for example, the higher digit matches more). Therefore, the index information is transmitted (transferred).

  In this way, the index registration request is transmitted (transferred) to another node device 1 until the root node device that stores the index information corresponding to the keyword is found, and the processing of FIG. 3B is performed. become.

(Content data search process)
Next, content data search processing will be described with reference to FIGS.

  FIG. 5 shows the flow of information in the content distribution system S when the location of content data is searched by one keyword. FIGS. 6 and 7 show the case where the location of content data is searched by two keywords. It is a figure which shows the flow of the information in the content delivery system S.

  FIG. 8 is a flowchart showing content data search processing in the control unit 11 of the node device 1 that searches for the location of content data using a keyword. FIGS. 9 and 10 are diagrams in the control unit 11 of the root node device 1. It is a flowchart which shows a content data search process.

  First, the flow of information in the content distribution system S when a keyword is used to search the location of content data will be described with reference to FIGS.

  First, in the case of a search mode using one keyword, when one keyword (for example, “flower”) is input in the node device 1c shown in FIG. 5, the search request to which the hash value of the keyword is added is sent to the node device. The search request is sent from the node 1c and sequentially transferred to the node devices 1d, 1e,... (The processing of each node device 1 at this time is performed in steps S11, S12, S16 shown in FIG. 3B). Finally, the node device 1x as the root node device having the hash value closest to the hash value of the keyword “flower” (for example, the higher digit matches more) is finally reached (FIG. 5). (I)).

  In the node device 1x, at least the location information of the content data included in the index information corresponding to the keyword “flower” is acquired, and the location information or the like is sent to the node device 1c that has sent the search request. On the other hand, it is returned as search result information ((ii) in FIG. 5). In the node device 1c, the node device 1a storing the content data related to the keyword “flower” is identified based on the search result information, and the content data is acquired from the node device 1a ( Download) ((iii) of FIG. 5).

  The search result information includes, in addition to the location information of the content data, information related to the network line attached to the node device 1 storing the content data (for example, a line type such as ADSL or FTTH), content data, and the like. Information about the network path (for example, the number of hops) between the stored node device 1 and the node device 1 that sent the search request, and how many times the data is acquired from the node device 1 that has stored the content data in the past It is also possible to include history information indicating whether (downloaded) has been performed. When the search result information includes location information of a plurality of content data, the number of hops of the network path between the node device 1c that has transmitted the search request and the node device 1 that stores the content data, ADSL, Considering line types such as FTTH, history information of data acquisition, etc., the node device is configured so that location information that is expected to be able to acquire content data faster and more safely is displayed preferentially. The user 1c may be able to select a node device that acquires (downloads) the content data. Further, in the display of the search result, it is assumed that a plurality of pieces of location information of content data different from the search result expected when the user of the node device 1c inputs the keyword (for example, search using the keyword “flower”) (For example, a search result including “fireworks” is returned), the keyword may be highlighted by some means.

  Next, in the case of the search mode 1 using two keywords, in the node device 1c shown in FIG. 6, two keywords (for example, “flower” and “Tokyo”) and search conditions (for example, AND) in which these two keywords are used. Is input from the node device 1c, for example, a hash value of the keyword “flower”, a keyword “Tokyo”, and a search condition are added. As in the case, the node devices 1d, 1e,... Are sequentially transferred to finally reach the node device 1x as the root node device having the hash value closest to the hash value of the keyword “flower”. ((I) of FIG. 6).

  In the node device 1x, the index information corresponding to the keyword “flower” is referred to, and the content data satisfying the AND condition of the two keywords “flower” and “Tokyo” (that is, the keyword “flower”). The location information of content data related to the keyword “Tokyo” (for example, content data including “Tokyo” in the name of the content)) is acquired from the index information corresponding to, and the location information etc. It is returned as search result information to the node device 1c that sent the request ((ii) in FIG. 6).

  In the node device 1c, the node device 1b storing the content data is specified based on the search result information, and the content data is acquired (downloaded) from the node device 1b ( (Iii) of FIG.

  Next, in the case of the search mode 2 using two keywords, in the node device 1c shown in FIG. 7, two keywords (for example, “flower” and “Tokyo”) and search conditions (for example, AND) in which these two keywords are used. Is input from the node device 1c, for example, a hash value of the keyword “flower”, a keyword “Tokyo”, and a search condition are added. As in the case, the node devices 1d, 1e,... Are sequentially transferred to finally reach the node device 1x as the root node device having the hash value closest to the hash value of the keyword “flower”. ((I) of FIG. 7).

  In the node device 1x, at least the location information of the content data included in the index information corresponding to the keyword “flower” is acquired, the location information, etc., the hash value of the keyword “Tokyo”, and A search request to which a search condition is added is sent from the node device 1x, and the search request is sequentially transferred to the node devices 1h, 1i,..., And finally the hash value of the keyword “Tokyo” The node device 1y as the root node device having the closest hash value is reached ((ii) in FIG. 7).

  In the node device 1y, at least content data location information included in the index information corresponding to the keyword “Tokyo” is acquired, and the location information of the content data related to the keyword “flower” is obtained. Based on the location information of the content data related to the keyword “Tokyo”, the location information of the content data that satisfies the AND condition of the keywords “flower” and “Tokyo” (for example, location information included in both) is The location information and the like are acquired and returned as search result information to the node device 1c that has sent the search request ((iii) in FIG. 7).

  In the node device 1c, the node device 1b storing the content data is specified based on the search result information, and the content data is acquired (downloaded) from the node device 1b ( (Iv) of FIG.

  In the case of the search mode 2 using two keywords, based on the location information of the content data related to the keyword “flower” and the location information of the content data related to the keyword “Tokyo”, the “flower” In addition, the node device 1c may be configured to perform processing for acquiring location information of content data that satisfies the AND condition of the keyword “Tokyo” instead of the node device 1y. In this case, the location information of the content data related to the keyword “flower” and the location information of the content data related to the keyword “Tokyo” are returned from the node device 1y to the node device 1c. The search condition need not be sent from the node device 1c.

  Next, content data search processing in each node device 1 will be described with reference to FIGS.

  Note that the content data search processing shown in FIG. 8 is performed by the location information search processing program stored and stored in the storage unit 12 or the like being executed by the control unit 11, whereby the control unit 11 can It functions as search information receiving means, identification information generating means, identification information transmitting means, location information receiving means, location information selecting means, and distribution information acquiring means.

  Similarly, the content data search processing shown in FIG. 9 and FIG. 10 is performed by the location information search processing program stored and saved in the storage unit 12 or the like being executed by the control unit 11, whereby the control unit 11 is , Functioning as identification information receiving means, location information acquisition means, location information return means, identification information generation means, and identification information transmission means of the present invention. This location information search processing program may be downloaded from a predetermined server on the network 8, for example, or recorded on a recording medium such as a CD-ROM and read via the drive of the recording medium. (The same applies to the location information registration processing program described above).

  For example, when the user of the node device 1c shown in any of FIGS. 5 to 7 operates the input unit 21 to input a content data search start instruction, the content data search process shown in FIG. 16, a keyword input screen (not shown) is displayed. In such a keyword input screen, for example, a keyword input field for inputting a keyword and a search condition setting field for setting a search condition are provided. A plurality of keywords can be input in the keyword input field, and one keyword must be input without fail. In the search condition setting field, when a plurality of keywords are input, search conditions using these keywords, for example, AND conditions, OR conditions, XOR conditions, and the like can be selected, and further, based on the search conditions. Logic operation setting is possible. There are three logical operation settings, for example, a setting for performing a logical operation in the node device 1 that issues a search request (in this case, for example, the logical operation flag is “0”), and a root node device in the middle Setting for performing logical operation (in this case, for example, the logical operation flag is “1”) and setting for performing logical operation in the final root node device (in this case, for example, the logical operation flag is “2”) There is.

  In such a keyword input screen display state, the user operates the input unit 21 to input a desired keyword in the keyword input field. When there are a plurality of keywords, a desired search is performed in the search condition setting field. When a condition is selected and the logical operation is set, the control unit 11 receives input keywords and the like (including search conditions and logical operation settings when there are a plurality of keywords) as search information receiving means ( Step S21).

  In the following description, when one keyword “flower” is input, two (first and second) keywords “flower” and “Tokyo” are input, and the search condition “AND condition”. Is selected (any of the above three settings for the logic operation setting), the three keywords “flower”, “Tokyo” and “yellow” are input, and the search condition “AND condition” It is assumed that either of the above is selected (any of the above three settings for the setting for performing the logical operation).

  In the following description, the node devices 1c, 1x, 1y, etc. shown in any of FIGS.

  Next, the control unit 11 generates, as the identification information generation unit, a hash value of the keyword by hashing the received keyword (for example, “flower”) using the common hash function described above (based on the keyword). An example of processing for generating unique identification information corresponding to the keyword) (step S22). When a plurality of keywords are received, one of the keywords (for example, the keyword input first) is hashed.

  Next, the control unit 11 adds at least the hash value of the keyword to the node device 1x as the root node device that stores the index information corresponding to the hashed keyword (for example, “flower”). The search request (for example, the device ID or IP address of the node device 1c is added to this search request in order to specify a return destination of search result information to be described later) is directly issued. (Meaning that a search request is directly transmitted from the node device 1c to the node device 1x) or indirectly (a search request is transmitted from the node device 1c to the node device 1x via the node devices 1d, 1e,...). This means that it is transmitted as identification information transmitting means via the communication unit 20 or the like (step S23).

  If a plurality of keywords are accepted in step S21, the search request includes not only the hash value of the keyword but also other accepted keywords (for example, “Tokyo”) and the search condition. (For example, “AND condition”) is added, and further, a logical operation flag corresponding to the logical operation setting is added.

  Next, when the node device 1x as the root node device receives the search request transmitted directly or indirectly from the node device 1c as the identification information receiving means via the communication unit 20 or the like, the content shown in FIG. The data search process is started, and first, the control unit 11 includes at least content included in the index information stored in the storage unit 12 (for example, index information corresponding to the hashed keyword “flower”). Data location information (first location information) or the like is acquired as location information acquisition means (all index information may be used) (step S31).

  Next, the control unit 11 determines whether or not there is another keyword (step S32). If there is no other keyword (step S32) (if no keyword (for example, “Tokyo”) is transmitted from the node device 1c) (step S32). : N), as the location information return means via the communication unit 20 or the like to the node device 1c that has sent the search request using the location information acquired in the step S31 as search result information (mode of FIG. 5 above) (Step S33), and the process ends.

  On the other hand, when there is another keyword in the above step S32 (when a keyword such as “Tokyo” is transmitted from the node device 1c, for example) (step S32: Y), the control unit 11 uses the logical operation flag. Is determined to be “1” (step S34).

  When the logical operation flag is not “1” (step S34: N), that is, when the logical operation based on the search condition in the route node device is prohibited, the control unit 11 serves as the identification information generating unit. The other keyword (for example, “Tokyo”) is hashed by the common hash function described above to generate a hash value of the keyword (step S35). Subsequently, the control unit 11 transmits at least the keyword (for example, for example) to the node device 1y as the root node device that stores the index information corresponding to the hashed keyword (for example, “Tokyo”). The search request to which the hash value of “Tokyo”), the location information acquired in step S31 and the search conditions are added is transmitted directly or indirectly as identification information transmitting means via the communication unit 20 or the like. (Step S36), the process ends. Here, when the third keyword (for example, “yellow”) is also accepted by the node device x, it is added to the search request for the keyword.

  On the other hand, when the logical operation flag is “1” in step S34 (step S34: Y), the control unit 11 serves as a location information acquisition unit for the hash value (for example, the keyword “flower” Based on the index information and the keyword (for example, “Tokyo”) corresponding to the “hash value”), the logical operation is performed to obtain the location information indicating the location of the content data that satisfies the search conditions (step S37), Set the logical operation completed flag to “1”. For example, as described above, the index information corresponding to the keyword “flower” is referred to, and the content data related to the keyword “Tokyo” is the AND condition of the two keywords “flower” and “Tokyo”. Content data that satisfies the conditions is obtained, and its location information and the like are acquired. Subsequently, the control unit 11 determines whether or not there is an unprocessed keyword (step S38). If there is no unprocessed keyword (step S38: N), the location information acquired in step S37 is displayed. A reply is sent to the node device 1c that has sent the search request as search result information (the mode shown in FIG. 6) (step S39), and the process ends.

  On the other hand, when there is an unprocessed keyword in step S38 (for example, when the third keyword (for example, “yellow”) is also received by the node device x) (step S38: Y), the unprocessed keyword is detected. The processing keyword (for example, “yellow”) is hashed with the common hash function described above to generate a hash value of the keyword (step S40). Subsequently, the control unit 11 applies at least the hash value of the keyword (for example, “yellow”) to the node device 1z as the root node device that stores the index information corresponding to the hashed keyword. The search request to which the location information acquired in step S37 and the search conditions are added is transmitted directly or indirectly (step S41), and the process is terminated.

  Next, when the node device 1y as the root node device receives the search request transmitted directly or indirectly from the node device 1x as the identification information receiving means via the communication unit 20 or the like, the contents shown in FIG. The data search process is started. First, the control unit 11 includes at least content data included in index information stored in the storage unit 12 (for example, index information corresponding to the hashed keyword “Tokyo”). Location information (second location information) and the like are acquired as location information acquisition means (step S51).

  Next, the control unit 11 determines whether or not there is another keyword (step S52), and when there is no keyword (when a keyword (for example, “yellow”) is not transmitted from the node device 1x) (step S52). : N), the controller 11 determines whether or not the logical operation flag is “2” (step S53).

  When the logical operation flag is not “2” (step S53: N), that is, when the logical operation based on the search condition in the final root node device is prohibited, the location information added to the search request or the like Then, the location information obtained in step S51 is returned as search result information to the node device 1c that has sent the search request as a location information return means via the communication unit 20 or the like (step S54). finish.

  On the other hand, if the logical operation flag is “2” in step S53 (step S53: Y), the location information (for example, content data related to the keyword “flower”) added to the search request as location information acquisition means. Based on the location information acquired in step S51 (for example, the location information of the content data related to the keyword “Tokyo”) and the like, a logical operation is performed to perform the above search condition (for example, AND condition) Location information indicating the location of the content data satisfying the condition (for example, location information included in both) is acquired (step S55), and the logical operation completed flag is set to “1”. Then, the control unit 11 returns the location information acquired in step S55 as search result information to the node device 1c that has sent the search request (the mode shown in FIG. 7) (step S56). finish.

  On the other hand, when there is another keyword in Step S52 (when a keyword (for example, “yellow”) is transmitted from the node device 1x) (Step S52: Y), the control unit 11 indicates that the logical operation flag is “ It is determined whether or not 1 ″ (step S57).

  When the logical operation flag is not “1” (step S57: N), the control unit 11 uses the above-described common hash function to hash the other keyword (for example, “yellow”) as the identification information generation unit. To generate a hash value of the keyword (step S58). Subsequently, the control unit 11 applies at least the hash value of the keyword (for example, “yellow”) to the node device 1z as the root node device that stores the index information corresponding to the hashed keyword. The location information and the like added to the search request, the location information obtained in step S51, and the search request to which the search conditions are added are directly or indirectly identified via the communication unit 20 and the like. Transmission is performed as a transmission means (step S59), and the process ends.

  On the other hand, when the logical operation flag is “1” in step S57 (step S57: Y), the control unit 11 serves as the location information acquisition means for adding location information (for example, the keyword “flower” , Etc.), the location information obtained in step S51, and the other keyword (for example, “yellow”), a logical operation is performed and the search condition ( For example, location information indicating the location of the content data satisfying the AND condition is acquired (step S60), and the logical operation completed flag is set to “1”. For example, as described above, the location information included in the location information of the content data related to the keyword “flower” and the location information etc. of the content data related to the keyword “Tokyo” is specified. The location information of the content data related to the identified keyword “yellow” is acquired.

  Next, as in step S38, the control unit 11 determines whether there is an unprocessed keyword (step S61). If there is no unprocessed keyword (step S61: N), the control unit 11 obtains it in step S60. The location information and the like are returned as search result information to the node device 1c that has sent the search request (step S62), and the process ends.

  On the other hand, if there is an unprocessed keyword in step S61 (step S61: Y), the unprocessed keyword is hashed with the above-described common hash function to generate a hash value of the keyword (step S63). . Subsequently, the control unit 11 sends at least the hash value of the keyword and the location acquired in step S60 to the node device as the root node device that stores the index information corresponding to the hashed keyword. A search request to which information or the like and a search condition or the like are added is transmitted directly or indirectly (step S64), and the process ends.

  In the above processing, the processing shown in FIG. 10 is also performed in the node device 1z that has received the search request to which the location information of the content data and the search conditions are added. Further, as the number of keywords input in the node device 1c increases, the number of route node devices that receive search requests increases accordingly, and the processing shown in FIG. 10 is also performed in such a route node device. become.

  Returning to the processing shown in FIG. 8, the node device 1c receives the search result information (including the location information of the content data) returned from the node device 1x or 1y which is the root node device via the communication unit 20 or the like. If it is received as location information receiving means (step S24: Y), it is determined whether or not the logical operation completed flag included in the search result information is “1” (step S25), and the logical operation completed flag is “1”. (Step S25: Y), since the logical operation based on the search condition (for example, AND condition) has already been performed, the control unit 11 causes the display unit 16 to display the received search result information. (Step S26).

  On the other hand, when the logical operation completion flag is not “0” (step S25: N), the control unit 11 performs logical operation based on the location information of the content data included in the search result information as the location information selection means. And the location information of the content data satisfying the search conditions is selected (step S27), and the selected location information is displayed as search result information on the display unit 16 (step S28).

  The selection of location information in step S27 is performed in the same manner as in step S55. For example, the location information of content data related to the keyword “flower” and the location information included in both the location information of content data related to the keyword “Tokyo” (ie, satisfying AND conditions) are selected. Will be.

  Next, the search result information displayed in step S26 or S28 in this way includes various information (for example, content name, copyright information, etc.) including location information of one or more content data. When the user operates the input unit 21 to select desired content data and inputs a content acquisition instruction, the control unit 11 responds to this (step S29: Y), and the selected node device 1 Is specified (that is, the IP address of the node device 1 storing the content data is specified), and a content acquisition request is transmitted to the specified node device 1 via the communication unit 20 or the like. Content data is acquired (downloaded) from the node device 1 as distribution information acquisition means (step S30), and the processing ends. When the search result information includes location information of a plurality of pieces of content data, the number of hops in the network path between the node device 1 that sent the search request and the node device 1 that stores the content data, ADSL, FTTH It is also possible to preferentially display location information that is expected to allow content data to be acquired more quickly and safely based on the line type such as data acquisition history information and the like.

  The acquired (distributed) content data is temporarily stored in the buffer memory 13 and decoded by the decoder unit 14, and then the video data and the like are displayed on the display unit 16 via the video processing unit 15. Then, the audio data is output from the speaker 18 via the audio processing unit 17.

  As described above, according to the above-described embodiment, index information that exists for each of a plurality of different keywords and includes location information indicating the location of content data related to the keyword is distributed as content distribution. Since it is configured to be distributed and stored in a plurality of node devices 1 participating in the system S, all the node devices 1 have common index information (including location information indicating the location of content data). Each node device 1 that does not need to hold the index information and can store the index information can manage (for example, update) only its own index information more efficiently as the root node device of each keyword.

  In addition, the index information corresponding to each keyword in the present embodiment is configured to be stored in the node device 1 having the device ID corresponding to the hash value closest to (most recent) the hash value of each keyword. Even when the content data is stored in the node device 1, it is more efficient just to extract the keyword of the content data, hash it, and send the location information of the content data together with the hash value to the content distribution system S. The location information of the content data can be registered in the index information corresponding to the keyword appropriately and quickly, and each node device 1 can be used even when the number of content data stored in a distributed manner is enormous. Hashes the input keyword and distributes the hash value to the content Only sends on the stem S, the location of the content data associated with the input keyword can be searched more efficiently and quickly.

  Furthermore, one index information in the present embodiment does not include location information of all content data, but only location information of content data related to one keyword. The data capacity (size) of the index information can be extremely reduced. Therefore, it is possible to sufficiently cope with a case where the storage capacity of the storage unit 12 in the node device 1 is limited, and the location information of the content data Search time can be drastically reduced.

  Furthermore, when a plurality of keywords and search conditions are input, the location information of the content data is acquired at the root node device of each keyword, and finally the location information of the content data satisfying the search conditions can be acquired. The location of desired content data can be searched more efficiently.

  In the above embodiment, it is assumed that the overlay network 9 is constructed by an algorithm using DHT. However, the present invention is not limited to this, and the same space as the device ID of the node device is used without using a hash function. Furthermore, the present invention can be applied to an overlay network constructed by another algorithm capable of arranging a unique keyword ID corresponding to a keyword. In this case, instead of performing the process of generating the hash value of the keyword using the hash function, the control unit 11 (record identification information generating means) is based on the keyword, and the keyword ID corresponding to the keyword (identifiable from others). ) Will be generated.

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. 2 is a diagram illustrating a schematic configuration example of a node device 1. FIG. (A) is a flowchart showing an index information registration process in the control unit 11 of the node device 1 that issues an index information registration request, and (B) is a control unit of the node device 1 that has received the index information registration request. 11 is a flowchart showing index information registration processing in FIG. It is a figure which shows an example of the list of the location information contained in the index information of keyword "flower". It is a figure which shows the flow of the information in the content delivery system S when the location of content data is searched with one keyword. It is a figure which shows the flow of the information in the content delivery system S when the location of content data is searched with two keywords. It is a figure which shows the flow of the information in the content delivery system S when the location of content data is searched with two keywords. It is a flowchart which shows the content data search process in the control part 11 of the node apparatus 1 (node apparatus 1c) which searches the location of content data using a keyword. It is a flowchart which shows the content data search process in the control part 11 of the root node apparatus 1 (node apparatus 1x). It is a flowchart which shows the content data search process in the control part 11 of the root node apparatus 1 (node apparatus 1y etc.).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Node apparatus 11 Control part 12 Storage part 13 Buffer memory 14 Decoder part 15 Video | video process part 16 Display part 17 Audio | voice process part 18 Speaker 19 Encoder part 20 Communication part 21 Input part 22 Bus S Content delivery system

Claims (19)

In an information distribution system comprising a plurality of node devices connected to each other via a network, distribution information to be distributed from one node device to another node device is distributed and stored in the plurality of node devices,
List information that exists for each of a plurality of different search information and includes location information indicating the location of distribution information related to the search information is distributed and stored in the plurality of node devices. An information distribution system characterized by The information distribution system according to claim 1,
Only one list information is stored in one node device, and the same list information is not stored redundantly in two or more node devices. . In the information delivery system according to claim 1 or 2,
The information distribution system, wherein the list information is stored in the node device having identification information closest to unique identification information corresponding to the search information related to the list information. In the information delivery system according to claim 3,
The information distribution system, wherein the identification information is a hash value obtained by a predetermined hash function. The node device in the information distribution system according to any one of claims 1 to 3,
Search information receiving means for receiving search information;
Identification information generating means for generating unique identification information corresponding to the search information based on the received search information;
Identification information transmitting means for directly or indirectly transmitting at least the generated identification information to the node device storing the list information corresponding to the search information;
Location information receiving means for receiving at least location information indicating the location of distribution information related to the search information, returned from a node device storing the list information corresponding to the search information. A node device characterized by the above. The node device according to claim 5, wherein
The node device to which the generated identification information is transmitted directly or indirectly is a node device having identification information closest to the generated identification information. In the node apparatus according to claim 5 or 6,
Distribution information for identifying one or a plurality of the node devices in which distribution information related to the search information is stored based on the received location information and acquiring the distribution information from the identified node devices And a node device. In the node apparatus as described in any one of Claim 5 thru | or 7,
The search information receiving means receives at least first search information and second search information different from each other, and at least a search condition in which the first search information and the second search information are used;
The identification information generating means generates unique first identification information corresponding to the first search information based on the first search information,
The identification information transmission means directly or indirectly outputs at least the generated first identification information and the second search information to the node device storing the list information corresponding to the first search information. Send
The location information receiving means is a location of distribution information related to at least the first search information returned from the node device storing the list information corresponding to any of the accepted search information. Receiving the second location information indicating the location of the distribution information related to the first location information and the second search information,
A node device further comprising location information selection means for selecting location information of distribution information satisfying the search condition based on the received first location information and second location information. In the node apparatus as described in any one of Claim 5 thru | or 7,
The search information receiving means receives at least first search information and second search information different from each other, and at least a search condition in which the first search information and the second search information are used;
The identification information generating means generates unique first identification information corresponding to the first search information based on the first search information,
The identification information transmitting means at least generates the first identification information, the second search information, and the search condition for the node device that stores the list information corresponding to the first search information. Send directly or indirectly,
The location information receiving means is a location indicating the location of distribution information satisfying at least the search condition returned from the node device storing the list information corresponding to any of the accepted search information. A node device receiving information. A node device comprising identification information receiving means for receiving at least the identification information transmitted directly or indirectly from the node device according to any one of claims 5 to 7,
List information storage means for storing the list information including location information indicating the location of distribution information related to at least one search information;
At least location information acquisition means for acquiring the location information included in the list information corresponding to the received identification information;
A node device comprising: a location information return unit that returns at least the acquired location information to the node device that transmitted the identification information. A node device comprising identification information receiving means for receiving at least the first identification information and the second search information transmitted directly or indirectly from the node device according to claim 8,
List information storage means for storing list information including first location information indicating the location of distribution information related to the first search information;
At least location information acquisition means for acquiring the first location information included in the list information corresponding to the received first identification information;
Identification information generating means for generating unique second identification information corresponding to the second search information based on the second search information;
At least the generated second identification information and the acquired first location information are transmitted directly or indirectly to the node device storing the list information corresponding to the second search information. A node device comprising: identification information transmitting means; A node device comprising identification information receiving means for receiving at least the second identification information and the first location information transmitted directly or indirectly from the node device according to claim 11,
List information storage means for storing list information including second location information indicating the location of distribution information related to the second search information;
At least location information acquisition means for acquiring the second location information included in the list information corresponding to the received second identification information;
A location information return means that returns at least the received first location information and the acquired second location information to the node device that has transmitted the first identification information. apparatus. A node device comprising identification information receiving means for receiving at least the first identification information, the second search information, and the search conditions, which are transmitted directly or indirectly from the node device according to claim 9. And
List information storage means for storing list information including first location information indicating the location of distribution information related to the first search information;
Location information acquisition means for acquiring location information indicating the location of distribution information satisfying the search condition based on at least the list information and the second search information corresponding to the received first identification information;
A node device comprising: a location information return unit that returns at least the selected location information to the node device that has transmitted the first identification information. The node device according to any one of claims 5 to 13,
The node device, wherein the identification information is a hash value obtained by a predetermined hash function. A location information search method for the node device in the information distribution system according to any one of claims 1 to 3,
Receiving the search information;
Generating unique identification information corresponding to the search information based on the received search information;
Transmitting the generated identification information directly or indirectly to the node device storing the list information corresponding to the search information; and
Receiving at least location information returned from a node device storing the list information corresponding to the search information and indicating the location of distribution information related to the search information. How to search for location information. A location information search method for a node device, comprising: identification information receiving means for receiving at least the identification information transmitted directly or indirectly from the node device according to any one of claims 5 to 7. ,
Storing the list information including location information indicating the location of distribution information related to at least one search information;
At least obtaining the location information included in the list information corresponding to the received identification information;
Returning the acquired location information to the node device that has transmitted the identification information. 5. A location information search method comprising: A computer included in the node device in the information distribution system according to any one of claims 1 to 3,
Search information receiving means for receiving search information,
Identification information generating means for generating unique identification information corresponding to the search information based on the received search information;
Identification information transmitting means for directly or indirectly transmitting at least the generated identification information to the node device storing the list information corresponding to the search information; and
Functioning as location information receiving means for receiving at least location information indicating the location of distribution information related to the search information, returned from the node device storing the list information corresponding to the search information. Location information search processing program characterized by A computer included in a node device comprising identification information receiving means for receiving at least the identification information transmitted directly or indirectly from the node device according to any one of claims 5 to 7.
List information storage means for storing the list information including location information indicating the location of distribution information related to at least one of the search information;
At least location information acquisition means for acquiring the location information included in the list information corresponding to the received identification information; and
A location information search processing program that causes at least the obtained location information to function as location information return means for returning the location information to a node device that has transmitted the identification information.   19. A recording medium in which the location information search processing program according to claim 17 is recorded so as to be readable by a computer.

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