JP2006285387A - Content delivery server, content delivery method, and content delivery program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently perform redelivery of a content between content receiving terminals. <P>SOLUTION: A content receiving terminal 3a requests delivery of a content to a content delivery server. The content delivery server 2 finds content receiving terminals 3b and 3d accumulating the content requested to deliver from a plurality of content receiving terminals. The content delivery server 2 detects the router number between the content receiving terminal 3a and each of the content receiving terminals 3b and 3d, and reports the content receiving terminal 3b with the smaller router number as an optimum delivery terminal to the content receiving terminal 3a. The content is redelivered from the content receiving terminal 3b to the content receiving terminal 3a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a content distribution server, a content distribution method, and a content distribution program that notify a content receiving terminal that has made a content distribution request to the content receiving terminal that has accumulated the content.

  As a form of distributing contents to a content receiving terminal that has requested distribution of contents, a form of distributing contents from a content distribution server to a content receiving terminal that is a distribution request source, and redistributing contents between content receiving terminals Forms have been put to practical use or proposed.

For example, a content distribution server that holds information of a content receiving terminal that stores content exists on the network, and the content distribution server searches for a content receiving terminal that stores the content requested to be distributed. Then, the content distribution server notifies the content receiving terminal that is the content distribution request source of the content receiving terminal found as a result of the search. Then, the content receiving terminal that is the distribution request source makes a content distribution request to the notified content receiving terminal, whereby the content is distributed to the content receiving terminal that is the distribution request source.
JP-T-2004-502987

  In a conventional content distribution system, a content distribution server holds information on a content receiving terminal that stores content, but information on a location of the content receiving terminal on the network and information on a distribution state of the content receiving terminal (for example, , Standby, delivery) etc. did not hold. For this reason, the content receiving terminal as the distribution request source cannot efficiently redistribute content such as receiving content redistribution from the content receiving terminal most suitable for distribution on the network.

  Therefore, an object of the present invention is to provide a content distribution server, a content distribution method, and a content distribution program that enable efficient redistribution of content between content receiving terminals.

  The content distribution server of the present invention is a content distribution server connected via a network to a plurality of content reception terminals that store content, and terminal information indicating the content reception terminal for each content reception terminal and the network of the content reception terminal Terminal information storage means for associating and storing the installation position information indicating the installation position connected to the terminal, content identification information for identifying the content, and terminal information indicating the content receiving terminal storing the content Storage terminal information storage means for storing in association with each other, and storage for retrieving each terminal information stored in the storage terminal information storage means in association with content identification information included in a content distribution request received from the content receiving terminal Terminal take-out means and storage terminal take-out means Installation position information extraction means for extracting the installation position information stored in the terminal information storage means in association with the terminal information for each of the terminal information extracted, and the installation position information of the content receiving terminal that has made the distribution request Of the content receiving terminal that has made the distribution request from among the content receiving terminals from which the terminal information has been extracted by the storage terminal extracting means, using the setting position information extracted by the installation position information extracting means Optimal distribution terminal detecting means for detecting the content receiving terminal at the shortest installation position relative to the position and making it the optimal distribution terminal, and terminal information of the content receiving terminal detected as the optimal distribution terminal by the optimal distribution terminal detecting means Terminal information transmitting means for transmitting to the content receiving terminal that made the content distribution request; Those were example.

  In the content distribution server, the terminal information storage means further stores the terminal information indicating the content receiving terminal in association with the line speed of the network to which the content receiving terminal is connected, and detects the optimum distribution terminal The means extracts and extracts the line speed stored in the terminal information storage means in association with the terminal information of the content receiving terminal for each of the detected content receiving terminals when the number of detected content receiving terminals is plural. The content receiving terminal with the maximum line speed is the optimum distribution terminal.

  In the content distribution server, the storage terminal information storage means further associates content identification information for identifying the content with terminal information indicating the content reception terminal storing the content, and the content reception terminal stores the content. Distribution status information indicating whether or not the transmission / reception is being transmitted / received, and the distribution status information stored in the storage terminal information storage means for each of the terminal information extracted by the storage terminal extraction means It further includes a distribution state determination unit that determines whether or not it indicates that transmission / reception is not being performed, and the optimum distribution terminal detection unit indicates that the distribution state information is not being transmitted / received by the distribution state determination unit. The content receiving terminal of the terminal information determined to be the detection target.

  In the content distribution server, the storage terminal information storage means stores the content identification information for identifying the content in association with terminal information indicating the content reception terminal storing the content in the content reception terminal. Is stored in the storage terminal information storage unit for each piece of terminal information extracted by the storage terminal extraction unit. The information processing apparatus further includes a use availability determination unit that determines whether or not the information indicates that the content can be used, and the optimum distribution terminal detection unit uses the content determination unit to determine whether the use availability information is used by the content. The content receiving terminal of the terminal information that has been determined to be possible is targeted for detection. It is intended.

  In the content distribution server, the terminal information transmitting unit transmits terminal information of all content receiving terminals that are determined as the optimal distribution terminals when the plurality of content receiving terminals are determined as the optimal distribution terminals by the optimal distribution terminal detection unit. Is.

  In the content distribution server, content storage means for storing content identification information for identifying content and the content in association with each other, and a terminal stored in association with the content identification information included in the content distribution request When the information is not in the storage terminal information storage unit, the content extraction unit extracts the content stored in the content storage unit in association with the content identification information included in the content distribution request, and the content extraction unit Content transmission means for transmitting the extracted content to the content receiving terminal that has requested the distribution of the content is further provided.

  In the content distribution server, the content stored in the content receiving terminal is encrypted, and content identification information for identifying the content and decryption for decrypting the encrypted content in which the content is encrypted A decryption key storage means for storing the key in association with each other; and a decryption key for extracting the decryption key stored in the decryption key storage means in association with the content identification information included in the decryption key request received from the content receiving terminal. And a decryption key transmitting means for transmitting the decryption key extracted by the decryption key extracting means to the content receiving terminal that has issued the decryption key request.

  The content distribution method of the present invention is a content distribution method performed by a content distribution server connected via a network to a plurality of content receiving terminals that store content, and stores content identification information for identifying the content and the content The storage terminal information storage means that stores the terminal information indicating the content receiving terminal that is associated with each other is inquired, and the storage is associated with the content identification information included in the content distribution request received from the content receiving terminal. Storage terminal extraction procedure for extracting each terminal information stored in the terminal information storage means, terminal information indicating the content receiving terminal for each content receiving terminal, and an installation position indicating an installation position connected to the network of the content receiving terminal Associate and store information An installation position information extraction procedure for inquiring the terminal information storage means and extracting the installation position information stored in the terminal information storage means in association with the terminal information for each of the terminal information extracted in the storage terminal extraction procedure; The content reception in which the terminal information is extracted in the storage terminal extraction procedure using the installation position information of the content receiving terminal that has made the distribution request and each of the installation position information extracted in the installation location information extraction procedure Optimal distribution terminal detection procedure for detecting the content receiving terminal at the shortest installation position with respect to the installation position of the content receiving terminal that has made the distribution request from the terminals, and making the optimal distribution terminal, and the optimal distribution terminal detection procedure Requested delivery of the content of the content receiving terminal detected as the optimal delivery terminal A terminal information transmitting step of transmitting relative content receiving terminal, and has a.

  The content distribution program of the present invention stores content identification information for identifying content and the content in a computer as a content distribution server connected via a network to a plurality of content receiving terminals that store the content. The storage terminal information storage means that stores the terminal information indicating the content receiving terminal in association with the storage terminal information is stored, and the storage terminal information storage is stored in association with the content identification information included in the content distribution request received from the content receiving terminal. Storage terminal extraction procedure for retrieving each terminal information stored in the means, terminal information indicating the content receiving terminal for each content receiving terminal, and installation position information indicating an installation position connected to the network of the content receiving terminal Terminal information storage hand that stores in association The installation position information extraction procedure for extracting the installation position information stored in the terminal information storage means in association with the terminal information for each of the terminal information extracted in the storage terminal extraction procedure, and the distribution request The content receiving terminal from which the terminal information was extracted in the storage terminal extraction procedure using the installation position information of the content receiving terminal that has performed and each of the installation position information extracted in the installation position information extraction procedure An optimal distribution terminal detection procedure that detects a content reception terminal at the shortest installation position with respect to an installation position of the content reception terminal that has made the distribution request to make an optimal distribution terminal, and an optimal distribution terminal in the optimal distribution terminal detection procedure Content reception requesting distribution of the content with terminal information of the content receiving terminal detected as It is intended to execute, a terminal information transmitting step of transmitting relative end.

  According to the present invention, the installation positions of the content receiving terminals connected to the respective networks are stored, and the respective content receptions that store the installation positions of the content receiving terminals that have made distribution requests and the contents that have been requested for distribution are stored. The content receiving terminal is used to determine the content receiving terminal to be notified to the content receiving terminal that has made the distribution request from among the plurality of content receiving terminals that have accumulated the content requested to be distributed using the location of the terminal. It becomes possible to efficiently redistribute content between terminals.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
First, the system configuration of the content distribution system in the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a system configuration diagram of a content distribution system according to the present embodiment. However, in this embodiment, the router name of the router to which the content receiving terminal is connected is set as the installation position information, and the shortest content receiving terminal with respect to the content receiving terminal has the number of routers through which data communication is performed. The least. Various forms are conceivable, such as the shortest content receiving terminal with respect to the content receiving terminal as the address (installation location) set as the installation position information, such that the actual distance between the installation locations is the shortest. .

  A content distribution system 1 shown in FIG. 1 includes a content distribution server 2 and a plurality of content reception terminals (only four content reception terminals 3a, 3b, 3c, and 3d are shown in the figure). The content distribution server 2 and the content receiving terminals 3a to 3d are connected to the network 4, respectively, whereby data transmission / reception between the content distribution server 2 and the content receiving terminals 3a to 3d, and the content receiving terminals 3a to 3d. Data transmission / reception between 3d is performed.

Next, a configuration example of the network in FIG. 1 will be described with reference to FIG. FIG. 2 is a diagram illustrating a configuration example of a network.
As shown in FIG. 2, the network 4 is constituted by a plurality of routers (only nine routers 4a to 4i are shown in the figure) which are network constituent devices. In the network configuration example shown in FIG. 2, the number of routers that pass between the content receiving terminal 3a and the content receiving terminal 3b is 3 (routers 4d, 4b, and 4f). The number of routers passing between the content receiving terminal 3a and the content receiving terminal 3d is 5 (routers 4d, 4b, 4a, 4c, 4i).

  Here, an outline of content redistribution (content distribution from a content receiving terminal to another content receiving terminal) in the content distribution system 1 will be described with reference to FIGS. 1 and 2.

  As an example, it is assumed that the content receiving terminal 3a requests content distribution, and the content receiving terminals 3b and 3d are content receiving terminals that store the requested content. It is assumed that the content receiving terminals 3b and 3d can be distributed together (the content is not redistributed with other content receiving terminals and the content holding period has not elapsed).

  The content receiving terminal 3a makes a content distribution request to the content distribution server. The content distribution server 2 searches for content receiving terminals 3b and 3d that store the content requested to be distributed from a plurality of content receiving terminals. Since the content receiving terminals 3b and 3d are capable of distributing content and there are two content receiving terminals that store the content requested to be distributed, the content distribution server 2 includes the content receiving terminal 3a and the content receiving terminal. The number “3” of routers passing through 3b is detected, and the number “5” of routers passing between the content receiving terminal 3a and the content receiving terminal 3d is detected. Then, the content distribution server 2 sets the content reception terminal 3b with the smaller number of routers to be the optimal distribution terminal and notifies the content reception terminal 3b to the content reception terminal 3a. The content receiving terminal 3a makes a content distribution request to the content receiving terminal 3b notified from the content distribution server 2, and the content is redistributed from the content receiving terminal 3b to the content receiving terminal 3a.

  As another example, it is assumed that the content receiving terminal 3a requests distribution of content, and there are content receiving terminals 3b and 3c as content receiving terminals storing the requested content, and the line speed of the content receiving terminal 3b. Is faster than the line speed of the content receiving terminal 3c. It is assumed that both the content receiving terminals 3b and 3c can be distributed.

  The content receiving terminal 3a makes a content distribution request to the content distribution server. The content distribution server 2 searches for content receiving terminals 3b and 3c that store the content requested to be distributed from a plurality of content receiving terminals. Since the content receiving terminals 3b and 3c are capable of distributing content and there are two content receiving terminals that store the content requested to be distributed, the content distribution server 2 includes the content receiving terminal 3a and the content receiving terminal. The number “3” of routers passing through 3b is detected, the number “3” of routers passing between the content receiving terminal 3a and the content receiving terminal 3c is detected, and the number of passing routers is the same. Furthermore, the content distribution server 2 compares the line speeds of the content receiving terminal 3b and the content receiving terminal 3c, and notifies the content receiving terminal 3a of the content receiving terminal 3b having a high line speed as the optimum distribution terminal. The content receiving terminal 3a makes a content distribution request to the content receiving terminal 3b notified from the content distribution server 2, and the content is redistributed from the content receiving terminal 3b to the content receiving terminal 3a.

  If there is no content receiving terminal that stores the content requested by the content receiving terminal 3a to the content distribution server 2, the content distribution server 2 distributes the content to the content receiving terminal 3a.

Next, the functional configuration of the content distribution server 2 constituting the content distribution system 1 shown in FIGS. 1 and 2 will be described with reference to FIG. FIG. 3 is a functional block diagram showing a functional configuration of the content distribution server 2.
The content distribution server 2 shown in FIG. 3 includes a content storage unit 201, a network configuration storage unit 202, a terminal information storage unit 203, a storage terminal information storage unit 204, a distribution request reception unit 205, a storage terminal information deletion unit 206, and storage terminal information. Extraction unit (storage terminal extraction means) 207, distribution state determination unit 208, availability determination unit 209, optimum distribution terminal detection unit 210, terminal information transmission unit 211, content extraction unit 212, content transmission unit 213, redistribution information reception unit 214, a first distribution state changing unit 215, a redistribution completion information receiving unit 216, a second distribution state changing unit 217, and storage unit information adding unit 218.

The content storage unit 201 is a storage device that stores content in association with content identification information (content ID) for identifying content uniquely assigned to the content.
The network configuration storage unit 202 is a storage device that stores, for example, a network configuration schematically shown in FIG. 2, that is, a connection relationship of routers that configure the network.

The terminal information storage unit 203 has an IP address (corresponding to terminal information) as terminal location information of the content receiving terminal for each content receiving terminal, a router name of the router to which the content receiving terminal is connected (corresponding to installation location information), This is a storage device that stores the line speed of the line to which the content receiving terminal is connected. An example is shown in FIG.
FIG. 4 is a diagram showing an example of the contents stored in the terminal information storage unit 203 of FIG. The table of the terminal information storage unit 203 shown as an example in FIG. 4 includes “terminal ID”, “terminal location information”, “connection router name”, and “line speed” as fields.
The field “terminal ID” stores a terminal identifier (terminal ID) for identifying a content receiving terminal that has been uniquely assigned to the content receiving terminal. The field “terminal position information” stores the IP address of the content receiving terminal of the corresponding field “terminal ID”. The field “connected router name” stores the name of the router to which the content receiving terminal of the corresponding field “terminal ID” is connected. The field “line speed” stores the line speed of the line to which the content receiving terminal of the corresponding field “terminal ID” is connected.
When the content distribution server 2 receives registration information (IP address, router name, line speed) from the content receiving terminals 3a to 3d, the terminal ID is paid out, and the paid out terminal ID and the received registration information are received. (IP address, router name, line speed) are stored in the terminal information storage unit 203.

The storage terminal information storage unit 204 includes an IP address (corresponding to terminal information) as terminal location information of a content receiving terminal that stores content, and a content holding period (contents) indicating the period during which the content receiving terminal stores content This is a storage device that stores distribution status information indicating whether or not the content receiving terminal is transmitting / receiving the content. An example is shown in FIG.
FIG. 5 is a diagram showing an example of the stored contents of the storage terminal information storage unit 204 of FIG. In the table of the content accumulation information storage unit 204 shown as an example in FIG. 5, there are “content ID”, “terminal location information”, “content holding period”, and “distribution state” as fields.
The field “content ID” stores the content ID. The field “terminal location information” stores the IP address of the content receiving terminal that stores the content of the corresponding field “content ID”. In the field “content retention period”, the last date (content retention period) in which the content receiving terminal of the corresponding field “terminal position information” accumulates the content of the corresponding field “content ID” is stored. The field “distribution status” stores distribution status information indicating whether or not the content receiving terminal in the corresponding field “terminal location information” is transmitting / receiving content, and the stored distribution status information is being transmitted / received. If it is, “Distributing”, and if it is not transmitting / receiving content, “Waiting”.

  The distribution request receiving unit 205 receives content distribution requests from the content receiving terminals 3 a to 3 d and outputs the received content distribution requests to the storage terminal information deleting unit 206. The content distribution server 2 receives content distribution requests received from the content receiving terminals 3a to 3d as the first content distribution request and the second and subsequent content distribution requests (other content for which the content receiving terminal is notified of the IP address). It is assumed that there is a distribution request when all content data cannot be received from the receiving terminal), and the data structure of both is the same.

  The distribution request includes an IP address (distribution request source IP address) of the content receiving terminal that is the distribution request source, a content ID of the content desired to be distributed, and an IP address of the content receiving terminal that could not receive the content distribution (hereinafter, And an unacceptable IP address) and the data size of the content that could be accumulated so far (hereinafter referred to as the accumulated data size). In the case of the first content distribution request, the impossible IP address is “blank”. In addition, in the case of the first content distribution request, the accumulated data size is “0”, and even in the case of the second and subsequent content distribution requests, the content could not be accumulated at all until then. In addition, the accumulated data size is “0”.

  The storage terminal information deletion unit 206 determines whether or not the disabled IP address included in the content distribution request input from the distribution request receiving unit 205 is “blank”. If it is not “blank”, the storage terminal information deletion unit 206 uses the IP address as a key in the storage terminal information storage unit 204, and the IP address of the field “terminal location information” matches the IP address included in the content distribution request. Search for a record and delete the information stored in the record found as a result of the search. The storage terminal information deleting unit 206 outputs the distribution request source IP address, the content ID, and the stored data size included in the content distribution request input from the distribution request receiving unit 205 to the storage terminal information extracting unit 207.

  The storage terminal information extraction unit 207 searches the storage terminal information storage unit 204 for a content reception terminal that stores the content with the content ID included in the distribution request, and the IP address and content of the content reception terminal found as a result of the search The retention period and distribution status information are extracted from the storage terminal information storage unit 204. Specifically, the storage terminal information extraction unit 207 records in the storage terminal information storage unit 204 that the value of the field “content ID” matches the content ID input from the storage terminal information deletion unit 206 using the content ID as a key. Search for. Then, if a matching record is found, the storage terminal information extracting unit 207 finds the IP address of the field “terminal location information”, the content holding period of the field “content holding period”, and the field “ The distribution status information of “distribution status” is extracted. The extracted IP address is referred to as an accumulated IP address. The storage terminal information extraction unit 207 then sets the extracted stored IP address, content holding period, and distribution status information, distribution request source IP address input from the storage terminal information deletion unit 206, content ID, and storage The data size is output to the distribution state determination unit 208. On the other hand, if no matching record is found, storage terminal information extraction unit 207 outputs the content ID and storage data size input from storage terminal information deletion unit 206 to content extraction unit 212.

  The distribution status determination unit 208 checks the distribution status information of the content receiving terminal that stores the content with the content ID included in the distribution request, and distributes the content from the content receiving terminal that stores the content with the content ID. Content receiving terminals whose information content is “standby” are candidates for content receiving terminals that are content redistribution sources. Specifically, the distribution status determination unit 208 indicates that the distribution status information is “standby” for each of the stored IP address, content holding period, and distribution status information sets input from the storage terminal information extraction unit 207. Judge whether there is. If there is a “standby” distribution status determination unit 208, each set of stored IP addresses whose content status information is “standby”, a set of content holding periods, and a storage terminal The distribution request source IP address, the content ID, and the accumulated data size input from the information extraction unit 207 are output to the availability determination unit 209. On the other hand, if there is no “standby” item, distribution state determination unit 208 outputs the content ID and the stored data size input from storage terminal information extraction unit 207 to content extraction unit 212.

  The availability determination unit 209 confirms the content holding period of the “standby” content receiving terminal that stores the content of the content ID included in the distribution request, and stores the content of the content ID “standby The content receiving terminals within the content holding period from among the content receiving terminals “” are candidates for the content receiving terminal that is the content redistribution source. Specifically, the availability determination unit 209 determines that the current time has passed the last date indicated by the content retention period for each of the stored IP address and content retention period pairs input from the distribution state determination unit 208. It is determined whether or not (whether it is within the retention period). If there are a plurality of items within the retention period, the availability determination unit 209 outputs the stored IP addresses of each set within the retention period to the terminal information extraction unit 210a of the optimum distribution terminal detection unit 210. Further, if there is only one within the holding period, the availability determination unit 209 outputs the accumulated IP addresses of the set within the holding period to the terminal information transmission unit 211. Furthermore, if there is nothing within the retention period, the availability determination unit 209 outputs the content ID and the accumulated data size input from the distribution state determination unit 208 to the content extraction unit 212.

The optimum distribution terminal detection unit 210 includes units that function as a terminal information extraction unit 210a, a minimum number-of-passages terminal specification unit 210b, and a maximum line speed terminal specification unit 210c.
The terminal information extraction unit 210a searches the terminal information storage unit 203 for a content receiving terminal within the holding period in which the content of the content ID included in the distribution request is stored, and the content receiving terminal found as a result of the search is searched for. The router name of the connected router and the line speed of the connected line are extracted from the terminal information storage unit 203. In addition, the terminal information extraction unit 210a extracts from the terminal information storage unit 203 the router name of the router to which the content receiving terminal that has made the distribution request is connected. Specifically, the terminal information extraction unit 210a uses the IP address as a key in the terminal information storage unit 203 for each stored IP address input from the availability determination unit 209 in the field “terminal location”. The record having the same IP address in the “information” is searched, and the router name in the field “connected router name” and the line speed in the field “line speed” of the record found as a result of the search are extracted. The terminal information extraction unit 210a outputs each of the set of the accumulated IP address, the extracted router name, and the extracted line speed to the minimum number-of-routes terminal specifying unit 210b. In addition, the terminal information extraction unit 210 a uses the IP address as a key in the terminal information storage unit 203 for the distribution request source IP address input from the availability determination unit 209 in the field “terminal location information”. A record with a matching IP address is searched, and the router name in the field “connected router name” of the record found as a result of the search is extracted. The terminal information extraction unit 210a outputs the combination of the distribution request source IP address and the extracted router name to the minimum number-of-routers terminal identification unit 210b.

  The minimum number-of-routers terminal specifying unit 210b performs data communication between each content receiving terminal in the holding period in which the content with the content ID included in the distribution request is stored and the content receiving terminal that has made the distribution request. Detect the number of routers through which data passes. Then, the minimum number-of-routers terminal specifying unit 210b stores the content receiving terminal and router that made the distribution request from among the content receiving terminals in the holding period in which the content of the content ID included in the distribution request is stored. A content receiving terminal with the smallest number of vias is detected. Specifically, the minimum number-of-routers terminal specifying unit 210b has a router with a router name included in the set for each of the stored IP address, router name, and line speed input from the terminal information extraction unit 210a. Based on the network configuration stored in the network configuration storage unit 202 using the router having the router name corresponding to the distribution request source IP address, the content reception terminal having the accumulated IP address and the content reception terminal having the distribution request source IP address The number of routers passing through is detected, and the content receiving terminal with the smallest number of vias is identified based on the detection result. If there is one content receiving terminal with the smallest number of vias, the minimum number-of-routes terminal specifying unit 210b outputs the accumulated IP address of the smallest content receiving terminal to the terminal information transmitting unit 211. On the other hand, if there are a plurality of content receiving terminals with the minimum number of vias, the minimum number-of-routes terminal specifying unit 210b sets each of the stored IP address of the content receiving terminal with the minimum number of vias and the line speed as the maximum line speed terminal. It outputs to the specific part 210c.

  The maximum line speed terminal specifying unit 210c connects from the content receiving terminals with the smallest number of passing through the router among the content receiving terminals in the holding period in which the content of the content ID included in the distribution request is stored. The content receiving terminal having the maximum line speed is detected. Specifically, the maximum line speed terminal specifying unit 210c uses the stored IP address input from the minimum number-of-passages terminal specifying unit 210b and the set of line speeds, and is included in the set with the maximum line speed. The stored IP address (one or more) is output to the terminal information transmission unit 211.

  The terminal information transmission unit 211 stores the IP address that has already been input from the availability determination unit 209, the IP address that has already been input from the minimum route number terminal specification unit 210b, or the storage that is input from the maximum line speed terminal specification unit 210c. The transmitted IP address (one or more) is transmitted to the content receiving terminal of the content distribution request source.

  The content extraction unit 212 uses the content ID as a key in the content storage unit 201 to request a content ID (content ID input from the storage terminal information extraction unit 207, content ID input from the distribution state determination unit 208, The content whose value of the field “content ID” matches the content ID input from the availability determination unit 209 is retrieved to extract the content. Then, the content extraction unit 212 stores the stored data size (the stored data size input from the storage terminal information extraction unit 207, the stored data size input from the distribution state determination unit 208, and the availability determination unit 209) in the extracted content. The content receiving terminal that has requested the content distribution using the stored data size) outputs the content data that has not been stored to the content transmitting unit 213.

  The content transmission unit 213 transmits the content data input from the content extraction unit 212 to the content receiving terminal that is the content distribution request source. After the content transmission is completed, the content transmission unit 213 uses the field “content ID” and the field “terminal position” of the storage terminal information storage unit 204 to transmit the content ID of the transmitted content and the IP address of the content receiving terminal of the content transmission destination. The information is newly stored in “information”, and the date (content holding period) obtained by adding a predetermined period to the current time is stored in the corresponding field “content holding period”, and the corresponding field “delivery state” Stores "waiting".

  The redistribution information receiving unit 214 receives the redistribution information including the IP address of the content receiving terminal that is the content redistribution source (hereinafter referred to as the redistribution source IP address) from the content receiving terminals 3a to 3d. The distribution information is output to the first distribution state changing unit 215.

  The first distribution state changing unit 215 uses the IP address as a key in the storage terminal information storage unit 204 for the redistribution source IP address input from the redistribution information receiving unit 214 in the field “terminal location information”. ”Is searched for a record with a matching IP address. Then, the first distribution state changing unit 215 changes the “distribution state” of each record found as a result of the search from “standby” to “distributing”.

  The redistribution completion information receiving unit 216 receives the redistribution completion information from the content receiving terminals 3a to 3d and outputs the received redistribution completion information to the second distribution state changing unit 217 and the storage terminal information addition 218. In the redistribution completion information, the content ID of the content accumulated in the redistribution destination content receiving terminal (accumulated content ID) and the IP address of the content receiving terminal of the content redistribution destination (hereinafter referred to as redistribution destination IP address). ), The IP address (redistribution source IP address) of the content receiving terminal that is the content redistribution source.

  The second distribution state changing unit 217 uses the IP address as a key for the redistribution source IP address input from the redistribution completion information receiving unit 216 in the redistribution source IP address field “terminal position” Search for a record that matches the IP address of "information". Then, the second distribution state changing unit 217 changes the “distribution state” of each record found as a result of the search from “distributing” to “standby”.

  The storage terminal information adding unit 218 newly adds the stored content ID and redistribution destination IP address input from the redistribution completion information receiving unit 216 to the field “content ID” and the field “terminal location information” of the storage terminal information storage unit 204. To store. Then, the storage terminal information adding unit 218 stores the date (content holding period) obtained by adding a predetermined period to the current time to the corresponding field “content holding period”, and the corresponding field “delivery” Stores "waiting" in "status".

Next, the functional configuration of the content receiving terminals 3a to 3d configuring the content distribution system 1 shown in FIGS. 1 and 2 will be described with reference to FIG. FIG. 6 is a functional block diagram showing a functional configuration of the content receiving terminals 3a to 3d.
As shown in FIG. 6, the content receiving terminals 3a to 3d include a content storage unit 301, a stored content information storage unit 302, a stored data size storage unit 303, a content ID input unit 304, a first distribution request unit 305, and distribution content reception. Unit 306, first content registration unit 307, terminal information reception unit 308, redistribution request unit 309, response reception unit 310, redistribution information transmission unit 311, redistribution content reception unit 312, second content registration unit 313, redistribution Each unit functions as a monitoring unit 314, a second distribution request unit 315, a redistribution completion information transmission unit 316, a redistribution request reception unit 317, a redistribution request response unit 318, a content extraction unit 319, and a content transmission unit 320. ing.

The content storage unit 301 is a storage device that stores the content of the content ID in association with the content ID.
The stored content information storage unit 302 is a storage device that stores a content holding period indicating the last date and time of holding this content in association with the content ID for each content stored in the content storage unit 301. Note that the content retention period is set from the content distribution server 2 to the content retention period after information (IP address or the like) of the content receiving terminal that has newly accumulated the content in the content distribution server 2 is stored in the accumulation terminal information storage unit 204. By being transmitted to the receiving terminals 3a to 3d, it is stored in the stored content information storage unit 302.
The accumulated data size storage unit 303 is a storage device that stores the data size (accumulated data size) of content that has already been redistributed and received.

The content ID input unit 304 is an input device that is used when the user of the content receiving terminals 3a to 3d inputs the content ID desired by the user, and outputs the content ID input to each unit as necessary. To do.
The first distribution request unit 305 is a content distribution request including the IP address (distribution request source IP address) of the content receiving terminal and the content ID input from the content ID input unit 304. A content distribution request (initial distribution request) with the storage data size “0” and “blank” is created. Then, the first distribution request unit 305 transmits the created content distribution request to the content distribution server 2.

The distribution content receiving unit 306 receives the content ID and the content transmitted by the content distribution server 2, and outputs them to the first content registration unit 307.
The first content registration unit 307 stores the content input from the distribution content reception unit 306 in the content storage unit 301 in association with the content ID of the content.

The terminal information receiving unit 308 receives the IP address (one or more) of the content receiving terminal that is the redistribution source of the content transmitted by the terminal information transmitting unit 211 of the content distribution server 2, and redistributes the received IP address Output to the request unit 309.
The redistribution request unit 309 creates a redistribution request including the content ID input from the content ID input unit 304 and the stored data size stored in the stored data size storage unit 303, and the generated redistribution request is transmitted to the terminal information. It transmits to the content receiving terminal of each IP address input from the receiving unit 308.

  The response receiving unit 310 receives a response from the content receiving terminal that has transmitted the redistribution request, determines whether the response is a distribution rejection response indicating that the distribution is not performed, and if the response is not a distribution rejection response, The IP address of the content receiving terminal that has made the (delivery response) is output to the redistribution information transmission unit 311. The response receiving unit 310 does not receive a response from another content receiving terminal without receiving a response from another content receiving terminal after receiving a response that is not a distribution rejection response.

  The redistribution information transmission unit 311 creates redistribution information including the IP address (redistribution source IP address) of the content receiving terminal (content receiving terminal that is the content redistribution source) that has made the distribution response. The redistribution information is transmitted to the content distribution server 2.

The redistributed content receiving unit 312 receives the content ID and the content transmitted from the redistribution source content receiving terminal, and outputs the content ID to the second content registering unit 313.
The second content registration unit 313 stores the content input from the redistributed content reception unit 312 in the content storage unit 301 in association with the content ID of the content, and accumulates the data size of the content stored in the content storage unit 301 It is stored in the data size storage unit 303.

  The redistribution monitoring unit 314 sends the content to the second distribution request unit 315 when the response receiving unit 310 cannot receive a response to the redistribution request from the content receiving terminal within a predetermined period, or when only the distribution rejection response is received. The first re-request instruction data is output so as to make another distribution request to the distribution server 2. In addition, when the redistribution content receiving unit 312 cannot continuously receive the content, the redistribution monitoring unit 314 makes a second distribution request to the content distribution server 2 to the second distribution request unit 315. In this way, the second re-request instruction data is output. If the content receiving terminal that is the redistribution source of the content is disconnected from the network for the purpose of the user, data communication cannot be performed between the content receiving terminals or cannot be performed continuously. In addition, data communication cannot be performed between content receiving terminals due to a network failure such as communication disconnection or cannot be performed continuously. If the content is deleted within the content holding period by the user's intention at the content receiving terminal as the content distribution source, the content receiving terminal as the content distribution destination cannot receive the content.

  When the first re-request instruction data is input from the re-distribution monitoring unit 314, the second distribution request unit 315 receives the IP address (distribution request source IP address) of the content receiving terminal and the content ID input unit 304. A content distribution request including the content ID and the stored data size stored in the stored data size storage unit 303, and a content distribution request having an impossible IP address of “blank” is created. Then, the second distribution request unit 315 transmits the created content distribution request to the content distribution server 2. However, the accumulated data size included in the distribution request is “0” when the content has not been received so far, and the partial data size when a part of the content has been received so far. become. In the latter case, for example, a part of the data can be obtained in the first distribution request, but if there is no response to the redistribution request in the second distribution request, the first distribution request in the third distribution request. Is the data size of the content received at.

  When the second re-request instruction data is input from the re-distribution monitoring unit 314, the second distribution request unit 315 is input from the IP address (distribution request source IP address) of the content receiving terminal and the content ID input unit 304. A content distribution request including the content ID, the IP address (impossible IP address) of the content receiving terminal that was the content redistribution source, and the accumulated data size stored in the accumulated data size storage unit 303 is created. Then, the second distribution request unit 315 transmits the created content distribution request to the content distribution server 2.

  When the redistribution completion information transmission unit 316 receives data of the entire content from the redistribution source content receiving terminal by the redistribution content receiving unit 312, the content ID (accumulated content ID) of the received content, the IP of the own content receiving terminal Redistribution completion information including the address (redistribution destination IP address) and the IP address (redistribution source IP address) of the content receiving terminal that is the content redistribution source is created. Then, the redistribution completion information transmission unit 316 transmits the created redistribution completion information to the content distribution server 2.

The redistribution request receiving unit 317 receives a content redistribution request from another content receiving terminal and outputs it to the redistribution request responding unit 318.
The redistribution request response unit 318 is configured such that the content receiving terminal transmits / receives content to / from other content receiving terminals, or the content with the content ID included in the redistribution request is stored in the content storage unit 301. Judgment is made. The redistribution request response unit 318 performs a distribution rejection response indicating a distribution rejection when content is transmitted / received or when the requested content is not stored. When the content is not transmitted / received or when the requested content is stored, a distribution response is made, and the content ID and the accumulated data size included in the redistribution request are output to the content extraction unit 319.

The content extraction unit 319 searches the content storage unit 301 for content whose field “content ID” matches the content ID input from the redistribution request response unit 318 using the content ID as a key, and extracts the content. Then, the content extraction unit 319 outputs content data that has not been stored to the content transmission unit 320 using the storage data size included in the distribution request in the extracted content.
The content transmission unit 320 transmits the content data input from the content extraction unit 319 to the content receiving terminal that is the redistribution request source.

  Next, content distribution processing performed by the content distribution server 2 in FIG. 1 will be described with reference to FIG. FIG. 7 is a flowchart showing the flow of content distribution processing performed by the content distribution server 2. However, FIG. 7 shows the flow of processing from receiving a content distribution request until notifying the content receiving terminal of the distribution request source of the content receiving terminal of the redistribution source.

  The distribution request receiving unit 205 waits to receive a content distribution request from the content receiving terminals 3a to 3d (step S101). Upon receiving the content distribution request, the storage terminal information deleting unit 206 responds to the content distribution request. It is determined whether or not the included IP address is “blank”. If the IP address is not “blank”, the field “ A record having the same IP address of “terminal position information” is searched, and information stored in the record found as a result of the search is deleted (step S102).

  The storage terminal information extraction unit 207 searches the storage terminal information storage unit 204 for a content reception terminal that stores the content with the content ID included in the distribution request (step S103). If there is an accumulated content receiving terminal (S103: YES), the process proceeds to step S104, and if there is no accumulated content receiving terminal (S103: NO), the process proceeds to step S107.

  The storage terminal information extraction unit 207 stores the IP address, content holding period, and distribution status information of the content receiving terminal that stores the content of the requested content ID found as a result of the search in step S103, in the storage terminal information storage It is extracted from the fields “terminal position information”, “content holding period”, and “distribution status” of the record whose value of the field “content ID” matches the content ID included in the distribution request in the section 204 (step S104).

  The distribution status determination unit 208 confirms the information stored in the “distribution status” extracted in step S104 of the content receiving terminal that has accumulated the content of the content ID requested for distribution, and the content ID requested for distribution. It is determined whether or not there is a content receiving terminal whose “distribution status” is “standby” among the content receiving terminals that store the content (step S105). If there is a "standby" content receiving terminal (S105: YES), the process proceeds to step S106, and if there is no "standby" content receiving terminal (S105: NO), the process proceeds to step S107.

  The availability determination unit 209 confirms the information stored in the “content holding period” extracted in step S104 of the “standby” content receiving terminal that stores the content with the content ID included in the distribution request. Then, it is determined whether there is a content receiving terminal whose current time is within the content holding period among the “waiting” content receiving terminals that store the content of the content ID included in the distribution request (step S106). . If there is a content receiving terminal within the content holding period (S106: YES), the process proceeds to step S109. If there is no content receiving terminal within the content holding period (S106: NO), the process proceeds to step S107.

  The content extraction unit 212 extracts the content with the content ID included in the distribution request from the content storage unit 301, and specifies the data portion of the content to be transmitted using the accumulated data size included in the distribution request (step S107). The content transmission unit 213 transmits the data portion of the specified content to the content receiving terminal that is the distribution request source (step S108).

  The availability determination unit 209 determines whether there is one content reception terminal or two or more content reception terminals that are in a standby state in which the content of the content ID requested for distribution is stored (step S109). If the number is one (S109: one), the process proceeds to step S110. If the number is two or more (S109: two or more), the process proceeds to step S111.

  The terminal information transmitting unit 211 transmits the IP address of the content receiving terminal within the content holding period while waiting to store the content of the content ID requested for distribution to the content receiving terminal that is the content distribution request source ( Step S110).

  The terminal information extraction unit 210a of the optimum distribution terminal detection unit 210 receives the content based on the IP address of each content reception terminal in the content holding period that is waiting and storing the content of the content ID requested for distribution. The router name of the router to which the terminal is connected and the line speed of the connected line are extracted from the terminal information storage unit 203, and the content receiving terminal that has made a content distribution request is used for the content receiving terminal using its IP address. The router name of the router to which the content receiving terminal is connected is extracted from the terminal information storage unit 203. The minimum number-of-routers terminal specifying unit 210b is the name of the router to which each content receiving terminal within the content holding period is connected while waiting to store the content of the content ID requested for distribution extracted by the terminal information extracting unit 210a. Within the standby content retention period in which the content with the content ID included in the distribution request is stored using the router of the router and the router with the name of the router connected to the content receiving terminal that made the content distribution request The number of routers through which data passes is detected in data communication between each content receiving terminal and the content receiving terminal that has requested distribution. Then, the minimum number-of-routers terminal specifying unit 210b stores the content receiving terminal and router that made the distribution request from among the content receiving terminals in the holding period in which the content of the content ID included in the distribution request is stored. The content receiving terminal with the smallest number of vias is detected (step S111).

  The minimum number-of-routers terminal specifying unit 210b determines whether or not there is one content receiving terminal with the minimum number of routers detected in step S111 (step S112). If there is one content receiving terminal with the smallest number of routed routers (S112: YES), the process proceeds to step S113, and if there is not one content receiving terminal with the smallest number of routed routers, that is, a plurality of content receiving terminals. (S112: NO) The process proceeds to step S114.

  The terminal information transmission unit 211 is a content receiving terminal that is waiting for storing the content of the content ID requested to be distributed and is within the content holding period, and has the smallest number of routers passed through in step S111. The address is transmitted to the content receiving terminal that is the content distribution request source (step S113).

The maximum line speed terminal specifying unit 210c connects from the content receiving terminals with the smallest number of passing through the router among the content receiving terminals in the holding period in which the content of the content ID included in the distribution request is stored. The content receiving terminal having the maximum line speed is detected (step S114).
The terminal information transmission unit 211 is a content receiving terminal that has the minimum number of routers in the content holding period during standby for storing the content of the content ID requested for distribution, and has the maximum line speed in step S114. The IP addresses of all the content receiving terminals detected as are transmitted to the content receiving terminal (s) that requested the content distribution (step S115).

  Next, content distribution processing performed by the content receiving terminals 3a to 3d in FIG. 1 will be described with reference to FIG. FIG. 8 is a flowchart showing the flow of content distribution processing performed by the content receiving terminals 3a to 3d. FIG. 8 shows the flow of processing in the content receiving terminal of the content distribution request source and redistribution request source.

  The first distribution request unit 305 includes the IP address of its own content receiving terminal and the content ID input from the content ID input unit 304, and the content with the impossible IP address “blank” and the accumulated data size “0”. A distribution request is created, and a distribution request for the created content is transmitted (step S201). Thereafter, the content receiving terminal waits to receive from the content distribution server 2 either the content or the IP address of the content receiving terminal storing the content, and determines whether the received information is the content (step). S202). When the content receiving terminal receives content by the distribution content receiving unit 306 (S202: YES), the process proceeds to step S203, and the first content registration unit 307 receives the content received by the distribution content receiving unit 306. Is stored in the content storage unit 301 in association with the content ID (step S203). On the other hand, when the content receiving terminal receives the IP address of the content receiving terminal storing the content by the terminal information receiving unit 308 (S202: NO), the process proceeds to step S204.

  The redistribution request unit 309 creates a redistribution request including the content ID input from the content ID input unit 304 and the stored data size stored in the stored data size storage unit 303, and the generated redistribution request is transmitted to the terminal information. The information is transmitted to the content receiving terminal (or terminals) of the IP address received by the receiving unit 308 (step S204). When a distribution response is received from the content receiving terminal that is the redistribution request destination after making the redistribution request, the redistribution information transmitting unit 311 of the content receiving terminal receives the IP address (redistribution) of the content receiving terminal that has made the distribution response. Redistribution information including the original IP address is created, and the created redistribution information is transmitted to the content delivery server 2.

  The redistribution monitoring unit 314 cannot receive the content from the redistribution request destination content receiving terminal (there is no response from the redistribution source content receiving terminal, the response from the redistribution source content receiving terminal is distribution refusal) It is determined whether or not communication, communication failure due to network problem, etc.) (step S205). If the content cannot be received from the redistribution request destination content receiving terminal (S205: YES), the process proceeds to step S206, and if the content can be received from the redistribution request destination content receiving terminal. (S205: NO) The process proceeds to step S208.

  The second distribution request unit 315 extracts the stored data size stored in the stored data size storage unit 303 (step S206), transmits the extracted stored data size, and the IP of the content receiving terminal that has transmitted or transmitted the content. The above-described content distribution request including an address or the like is created, and the created content distribution request is transmitted to the content distribution server 2 (step S207).

  The second content registration unit 313 stores the content received by the redistributed content reception unit 312 in the content storage unit 301 in association with the content ID (step S208).

  Next, content distribution processing performed by the content receiving terminals 3a to 3d in FIG. 1 will be described with reference to FIG. FIG. 9 is a flowchart showing the flow of content distribution processing performed by the content receiving terminals 3a to 3d. FIG. 9 shows the flow of processing in the content receiving terminal that is the content redistribution request destination.

  Waiting for the redistribution request receiving unit 317 to receive a redistribution request for content from the content receiving terminal (step S301). When the redistribution request receiving unit 317 receives the redistribution request, the redistribution request responding unit 318 It is determined whether the distribution is possible (whether the content receiving terminal is not transmitting / receiving content to / from other content receiving terminals or storing the requested content) (step S302). If redistribution is not possible (S302: NO), the redistribution request response unit 318 makes a response indicating distribution rejection (step S303). If redistribution is possible (S302: YES), the redistribution request response unit 318 makes a distribution response. The content retrieval unit 319 retrieves content from the content storage unit 301 using the content ID included in the redistribution request, specifies the data portion of the content to be redistributed using the accumulated data size included in the redistribution request, The content transmitting unit 320 transmits the content of the specified data portion to the content receiving terminal that is the redistribution request source (step S304).

Next, content distribution processing performed in the content distribution system 1 of FIG. 1 will be described with reference to FIG. FIG. 10 is a sequence diagram illustrating an example of the flow of content distribution processing performed in the content distribution system 1.
The first distribution request unit 305 of the content receiving terminal 3a transmits a content distribution request to the content distribution server 2, and the transmitted distribution request is received by the distribution request reception unit 205 of the content distribution server 2 (step S401). ). The content distribution server 2 detects the optimum content receiving terminal 3b by performing the above-described processing of FIG. 7 (step S402). The terminal information transmission unit 211 of the content distribution server 2 transmits the IP address of the optimum content reception terminal 3b to the content reception terminal 3a that is the distribution request source, and the transmitted IP address of the content reception terminal 3b is the content reception terminal 3a. Is received by the terminal information receiving unit 308 (step S403).

  The redistribution request unit 309 of the content receiving terminal 3a transmits the redistribution request to the content receiving terminal 3b of the IP address received in step S403, and the redistribution request transmitted is the redistribution request receiving unit of the content receiving terminal 3b. It is received by 317 (step S404). The redistribution request response unit 318 of the content receiving terminal 3b performs a response (distribution response) for distributing the redistribution request, and the response receiving unit 310 of the content receiving terminal 3a receives the distribution response (step S405). The redistribution information transmitting unit 311 of the content receiving terminal 3a transmits redistribution information including the IP address of the content receiving terminal 3b that is a redistribution source to the content distribution server 2, and the transmitted redistribution information is the content distribution server. 2 is received by the second redistribution information receiving unit 214 (step S406). The first distribution state changing unit 215 of the content distribution server 2 matches the IP address of the field “terminal location information” with the IP address of the content receiving terminal 3 b included in the redistribution information stored in the storage terminal information storage unit 204. The field “delivery status” of each record is changed from “standby” to “delivering”.

  The content extracting unit 319 of the content receiving terminal 3b extracts the content with the content ID included in the redistribution request from the content storage unit 301. Then, the content transmitting unit 320 transmits the extracted content to the content receiving terminal 3a, and the transmitted content is received by the redistributed content receiving unit 312 of the content receiving terminal 3a (step S407). Then, the content received at the content receiving terminal 3 a is stored in the content storage unit 301 by the second content registration unit 313.

  After the content receiving terminal 3a receives all of the content, the redistribution completion information transmitting unit 316 of the content receiving terminal 3a receives the content ID of the received content, the IP address of the content receiving terminal 3a, and the content redistribution source Re-distribution completion information including the IP address of the content receiving terminal 3b is transmitted to the content distribution server 2. Then, the transmitted redistribution completion information is received by the redistribution completion information receiving unit 216 of the content distribution server 2 (step S408). The second distribution state changing unit 217 of the content distribution server 2 matches the IP address of the field “terminal location information” with the IP address of the content receiving terminal 3 b included in the redistribution completion information stored in the storage terminal information storage unit 204. The field “delivery status” of each record to be changed is changed from “delivering” to “standby”. Then, the storage terminal information adding unit 218 newly adds the content ID included in the redistribution completion information and the IP address of the content receiving terminal 3a to the field “content ID” and the field “terminal location information” of the storage terminal information storage unit 204. And stores the date (content holding period) obtained by adding a predetermined period to the current time in the corresponding field “content holding period”, and “standby” in the corresponding field “delivery state” Is stored.

Next, content distribution processing performed in the content distribution system 1 of FIG. 1 will be described with reference to FIG. FIG. 11 is a sequence diagram illustrating an example of the flow of content distribution processing performed in the content distribution system 1.
The first distribution request unit 305 of the content receiving terminal 3a transmits a content distribution request to the content distribution server 2, and the transmitted distribution request is received by the distribution request receiving unit 205 of the content distribution server 2 (step S501). ). The content distribution server 2 detects the optimum content receiving terminal 3b by performing the above-described processing of FIG. 7 (step S502). The terminal information transmission unit 211 of the content distribution server 2 transmits the IP address of the optimum content reception terminal 3b to the content reception terminal 3a that is the distribution request source, and the transmitted IP address of the content reception terminal 3b is the content reception terminal 3a. Is received by the terminal information receiving unit 308 (step S503).

  The redistribution request unit 309 of the content receiving terminal 3a transmits the redistribution request to the content receiving terminal 3b having the IP address received in step S503 (step S504). Since the response receiving unit 310 of the content receiving unit 3a could not receive a response from the content receiving terminal 3b (step S505), the second distribution requesting unit 315 obtains the IP address and content ID of its own content receiving terminal 3a. Including a distribution request whose content IP address is the IP address of the content receiving terminal 3b and whose stored data size is “0” is transmitted to the content distribution server 2, and the transmitted distribution request is distributed by the content distribution server 2. The request is received by the request receiving unit 205 (step S506). The content distribution server 2 performs the above-described processing of FIG. 7 to delete the content receiving terminal 3b having the impossible IP address from the storage terminal information storage unit 204 and detect the optimum content receiving terminal 3c (step S507). The terminal information transmitting unit 211 of the content distribution server 2 transmits the IP address of the optimum content receiving terminal 3c to the content receiving terminal 3a that is the distribution request source, and the transmitted IP address of the content receiving terminal 3c is the content receiving terminal 3a. Is received by the terminal information receiving unit 308 (step S508).

  The redistribution request unit 309 of the content receiving terminal 3a transmits the redistribution request to the content receiving terminal 3c of the IP address received in step S508, and the redistribution request transmitted is the redistribution request receiving unit of the content receiving terminal 3c. It is received by 317 (step S509). The redistribution request response unit 318 of the content receiving terminal 3c makes a response (distribution response) for distributing the redistribution request, and the response receiving unit 310 of the content receiving terminal 3a receives the distribution response (step S510). The redistribution information transmission unit 311 of the content receiving terminal 3a transmits redistribution information including the IP address of the content receiving terminal 3c that is the redistribution source to the content distribution server 2, and the transmitted redistribution information is the content distribution server. 2 is received by the redistribution information receiving unit 214 (step S511). The first distribution state changing unit 215 of the content distribution server 2 matches the IP address of the field “terminal location information” with the IP address of the content receiving terminal 3 c included in the redistribution information stored in the storage terminal information storage unit 204. The field “delivery status” of each record is changed from “standby” to “delivering”.

  The content extraction unit 319 of the content receiving terminal 3c extracts the content with the content ID included in the redistribution request. Then, the content transmitting unit 320 transmits the extracted content to the content receiving terminal 3a, and the transmitted content is received by the redistributed content receiving unit 312 of the content receiving terminal 3a (step S512). Then, the content received at the content receiving terminal 3 a is stored in the content storage unit 301 by the second content registration unit 313.

  After the content receiving terminal 3a receives all of the content, the redistribution completion information transmitting unit 316 of the content receiving terminal 3a receives the content ID of the received content, the IP address of the content receiving terminal 3a, and the content redistribution source The redistribution completion information including the IP address of the content receiving terminal 3c is transmitted to the content distribution server 2, and the transmitted redistribution completion information is received by the redistribution completion information receiving unit 216 of the content distribution server 2 (step). S513). The second distribution state changing unit 217 of the content distribution server 2 matches the IP address of the field “terminal location information” with the IP address of the content receiving terminal 3 c included in the redistribution completion information stored in the storage terminal information storage unit 204. The field “delivery status” of each record to be changed is changed from “delivering” to “standby”. Then, the storage terminal information adding unit 218 newly adds the content ID included in the redistribution completion information and the IP address of the content receiving terminal 3a to the field “content ID” and the field “terminal location information” of the storage terminal information storage unit 204. And stores the date (content holding period) obtained by adding a predetermined period to the current time in the corresponding field “content holding period”, and “standby” in the corresponding field “delivery state” Is stored.

Next, content distribution processing performed in the content distribution system 1 of FIG. 1 will be described with reference to FIG. FIG. 12 is a sequence diagram illustrating an example of the flow of content distribution processing performed in the content distribution system 1.
The first distribution request unit 305 of the content receiving terminal 3a transmits a content distribution request to the content distribution server 2, and the transmitted distribution request is received by the distribution request receiving unit 205 of the content distribution server 2 (step S601). ). The content distribution server 2 detects the optimum content receiving terminal 3b by performing the above-described processing of FIG. 7 (step S602). The terminal information transmission unit 211 of the content distribution server 2 transmits the IP address of the optimum content reception terminal 3b to the content reception terminal 3a that is the distribution request source, and the transmitted IP address of the content reception terminal 3b is the content reception terminal 3a. Is received by the terminal information receiving unit 308 (step S603).

  The redistribution request unit 309 of the content receiving terminal 3a transmits the redistribution request to the content receiving terminal 3b of the IP address received in step S503, and the transmitted redistribution request is the redistribution request receiving unit of the content receiving terminal 3b. It is received by 317 (step S604). The redistribution request response unit 318 of the content receiving terminal 3b performs a response (distribution response) for distributing the redistribution request, and the response receiving unit 310 of the content receiving terminal 3a receives the distribution response (step S605). The redistribution information transmitting unit 311 of the content receiving terminal 3a transmits redistribution information including the IP address of the content receiving terminal 3b that is a redistribution source to the content distribution server 2, and the transmitted redistribution information is the content distribution server. 2 is received by the redistribution information receiving unit 214 (step S606). The first distribution state changing unit 215 of the content distribution server 2 matches the IP address of the field “terminal location information” with the IP address of the content receiving terminal 3 b included in the redistribution information stored in the storage terminal information storage unit 204. The field “delivery status” of each record is changed from “standby” to “delivering”.

  The content extracting unit 319 of the content receiving terminal 3b extracts the content with the content ID included in the redistribution request. Then, the content transmitting unit 320 transmits the extracted content to the content receiving terminal 3a, and the transmitted content is received by the redistributed content receiving unit 312 of the content receiving terminal 3a (step S607). Then, the content received at the content receiving terminal 3 a is stored in the content storage unit 301 by the second content registration unit 313. If the content receiving terminal 3a cannot receive the content from the content receiving terminal 3b due to the communication interruption in the middle (step S608), the second content receiving terminal 3a stores the content stored so far in the content storage unit 301. The data size is calculated and stored in the accumulated data size storage unit 303. Then, the second distribution request unit 315 includes the IP address and content ID of the content receiving terminal 3a, the impossible IP address is the IP address of the content receiving terminal 3b, and the stored data size can be received from the content receiving terminal 3b. The distribution request having the data size is transmitted to the content distribution server 2, and the transmitted distribution request is received by the distribution request receiving unit 205 of the content distribution server 2 (step S609). The content distribution server 2 performs the above-described processing of FIG. 7 to delete the content receiving terminal 3b having the impossible IP address from the storage terminal information storage unit 204 and detect the optimum content receiving terminal 3c (step S610). The terminal information transmitting unit 211 of the content distribution server 2 transmits the IP address of the optimum content receiving terminal 3c to the content receiving terminal 3a that is the distribution request source, and the transmitted IP address of the content receiving terminal 3c is the content receiving terminal 3a. Is received by the terminal information receiving unit 308 (step S611).

  The redistribution request unit 309 of the content receiving terminal 3a sends a redistribution request including the content ID and the data size (accumulated data size) of the content received from the content receiving terminal 3b to the content receiving terminal 3c having the IP address received in step S611. The redistribution request transmitted is received by the redistribution request receiving unit 317 of the content receiving terminal 3b (step S612). The redistribution request response unit 318 of the content receiving terminal 3c performs a response (distribution response) for distributing the redistribution request, and the response receiving unit 310 of the content receiving terminal 3a receives the distribution response (step S613). The redistribution information transmitting unit 311 of the content receiving terminal 3a transmits redistribution information including the IP address of the content receiving terminal 3c that is a redistribution source to the content distribution server 2, and the transmitted redistribution information is the content distribution server. 2 is received by the redistribution information receiving unit 214 (step S614). The first distribution state changing unit 215 of the content distribution server 2 matches the IP address of the field “terminal location information” with the IP address of the content receiving terminal 3 c included in the redistribution information stored in the storage terminal information storage unit 204. The field “delivery status” of each record is changed from “standby” to “delivering”.

  The content extraction unit 319 of the content receiving terminal 3c extracts the content with the content ID included in the redistribution request, and uses the stored data size included in the redistribution request to extract the data portion of the content that is not stored in the content receiving terminal 3a. Identify. Then, the content transmitting unit 320 transmits the content of the specified data portion to the content receiving terminal 3a, and the transmitted content is received by the redistributed content receiving unit 312 of the content receiving terminal 3a (step S615). Then, the content received at the content receiving terminal 3 a is stored in the content storage unit 301 by the second content registration unit 313.

  After the content receiving terminal 3a receives all of the content, the redistribution completion information transmitting unit 316 of the content receiving terminal 3a receives the content ID of the received content, the IP address of the content receiving terminal 3a, and the content redistribution source The redistribution completion information including the IP address of the content receiving terminal 3c is transmitted to the content distribution server 2, and the transmitted redistribution completion information is received by the redistribution completion information receiving unit 216 of the content distribution server 2 (step). S616). The second distribution state changing unit 217 of the content distribution server 2 matches the IP address of the field “terminal location information” with the IP address of the content receiving terminal 3 c included in the redistribution completion information stored in the storage terminal information storage unit 204. Change the field “delivery status” of the record to be changed from “delivering” to “waiting”. Then, the storage terminal information adding unit 218 newly adds the content ID included in the redistribution completion information and the IP address of the content receiving terminal 3a to the field “content ID” and the field “terminal location information” of the storage terminal information storage unit 204. And stores the date (content holding period) obtained by adding a predetermined period to the current time in the corresponding field “content holding period”, and “standby” in the corresponding field “delivery state” Is stored.

  According to the embodiment of the present invention described above, among the content receiving terminals that store the content of the requested content ID, the content receiving terminal with the minimum number of transits between the requested content receiving terminal and the router is Be notified. For this reason, the number of routers through which content is redistributed between content receiving terminals is reduced, and efficient content redistribution is possible while reducing the load on the entire network. In addition, since the content receiving terminal having the maximum line speed is notified from the content receiving terminals that store the content of the requested content ID, the time required for redistributing the content between the content receiving terminals is shortened. be able to.

  Further, the content receiving terminal to be notified is detected from the content receiving terminals that store the content of the requested content ID, except for the content receiving terminal that is being distributed and the content receiving terminal that has passed the content holding period. Yes. For this reason, it is possible to avoid a situation in which the content receiving terminal that is the redistribution request source is distributing or not already holding the content.

  In addition, if communication is interrupted after receiving a part of the content, the content is already received because the content distribution server and other content receiving terminals are requested including the data size of the accumulated content. The part that has been done is not sent and received again, and the amount of data communication can be reduced.

  Hereinafter, modifications of the above embodiment will be described. In the modification, encrypted content (encrypted content) is transmitted from the content distribution server to the content receiving terminal, and from the content receiving terminal to another content receiving terminal. The portions other than the portions related to the encryption and decryption of the content are substantially the same as those in the above embodiment.

  The content distribution server 2 includes an encryption unit that encrypts content using an encryption key. In the content storage unit 201, content encrypted by the encryption unit (encrypted content) is associated with a content ID. Is remembered. The content distribution server 2 includes a decryption key storage unit that stores a decryption key for decrypting the encrypted content in association with the content ID.

  Similar to the above embodiment, the encrypted content is stored in the content receiving terminal that is the content distribution request source. Thereafter, the content receiving terminal storing the encrypted content transmits a decryption key request including the content ID to the content distribution server 2 (decryption key request means), and the content distribution server 2 receives the decryption key request (decryption key request). Receiving means). When the content distribution server receives the decryption key request, the content distribution server 2 uses the content ID included in the decryption key request to extract the decryption key stored in the decryption key storage unit in association with the content ID (decryption). Key retrieval means). Then, the content distribution server 2 transmits the extracted decryption key to the content receiving terminal requesting the decryption key (decryption key transmitting means), and the content receiving terminal requesting the decryption key receives the transmitted decryption key ( Decryption key receiving means). The content receiving terminal that requested the decryption key uses the received decryption key to decrypt the encrypted content (content decryption means), reproduces the decrypted content, and displays it on the display, for example.

  According to the above modification, since the decryption key is obtained from the content distribution server when browsing the encrypted content, the content distribution server can be charged for the content. Can be copyrighted.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various design changes can be made as long as they are described in the claims. Yes.
For example, in the above-described embodiment, when there are a plurality of content receiving terminals within the “standby” content holding period in which content is stored, the content receiving terminal that notifies the content receiving terminal with the smallest number of passing through the router In addition, when there are a plurality of content receiving terminals with the smallest number of routers, the content receiving terminal notifies the content receiving terminal with the maximum line speed. For example, a value obtained by adding a value obtained by multiplying the number of passing routers by a first weighting value and a value obtained by multiplying the line speed by a second weighting value is used, and the added value is the maximum content reception. It may be a content receiving terminal that notifies the terminal.

  In addition, the “delivery status” of the content receiving terminal that stores the content stores whether it is being distributed or in standby, but the “distribution status” is not a candidate for the content receiving terminal of the distribution source When the content receiving terminal is selected using the “distribution state”, it is determined whether or not the current time is within the period, and the contents outside the period are selected. For example, as the mechanism, when the redistribution information is received from the content receiving terminal, the “distribution status” of each record in which the IP address of the field “terminal location information” matches the IP address (redistribution source IP address) included therein. A value obtained by adding a predetermined time to the current time is stored.

  Note that a program for realizing the function of each processing unit of the above-described system is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into the computer system and executed, thereby executing the above-described program. Processing may be performed. The “computer system” here includes an OS and hardware such as peripheral devices. The “computer system” includes a WWW system provided with a homepage providing environment (or display environment). The “computer-readable recording medium” refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, and a CD-ROM, and a storage device such as a hard disk built in the computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

The system block diagram of the content delivery system in embodiment of this invention. The figure which shows the structural example of the network of FIG. The functional block diagram which shows the function structure of the content delivery server of FIG. The figure which shows an example of the memory content of the terminal information storage part of FIG. The figure which shows an example of the memory content of the storage terminal information storage part of FIG. The functional block diagram which shows the function structure of the content receiving terminal of FIG. The flowchart which shows the flow of the content delivery process which the content delivery server of FIG. 1 performs. The flowchart which shows the flow of the content delivery process which the content receiving terminal of FIG. 1 performs. The flowchart which shows the flow of the content delivery process which the content receiving terminal of FIG. 1 performs. The sequence diagram which shows an example of the flow of the content delivery process which the content delivery system of FIG. 1 performs. The sequence diagram which shows an example of the flow of the content delivery process which the content delivery system of FIG. 1 performs. The sequence diagram which shows an example of the flow of the content delivery process which the content delivery system of FIG. 1 performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Content distribution system 2 Content distribution server 3a-3d Content receiving terminal

Claims (9)

In a content distribution server connected via a network to a plurality of content receiving terminals that store content,
Terminal information storage means for storing terminal information indicating a content receiving terminal for each content receiving terminal and installation position information indicating an installation position connected to the network of the content receiving terminal in association with each other;
Storage terminal information storage means for storing content identification information for identifying content and terminal information indicating a content receiving terminal storing the content in association with each other;
Storage terminal extraction means for extracting each terminal information stored in the storage terminal information storage means in association with content identification information included in a content distribution request received from the content reception terminal;
Installation position information extraction means for extracting the installation position information stored in the terminal information storage means in association with the terminal information for each of the terminal information extracted by the storage terminal extraction means;
Using the installation position information of the content receiving terminal that has made the distribution request and each of the installation position information extracted by the installation position information extraction means, the content reception terminal from which the terminal information has been extracted by the storage terminal extraction means Optimal distribution terminal detection means for detecting the content reception terminal at the shortest installation position relative to the installation position of the content reception terminal that has made the distribution request from among the optimal distribution terminal;
Terminal information transmitting means for transmitting the terminal information of the content receiving terminal detected as the optimal distribution terminal by the optimal distribution terminal detecting means to the content receiving terminal that has made the content distribution request;
A content distribution server comprising: The terminal information storage means further stores the terminal information indicating the content receiving terminal in association with the line speed of the network to which the content receiving terminal is connected,
The optimum distribution terminal detecting unit is configured to store a line stored in the terminal information storage unit in association with the terminal information of the content receiving terminal for each of the plurality of detected content receiving terminals when the number of detected content receiving terminals is plural. 2. The content distribution server according to claim 1, wherein a content receiving terminal having a maximum line speed is selected as an optimum distribution terminal. Whether the storage terminal information storage means is associated with content identification information for identifying content and terminal information indicating the content reception terminal storing the content, and whether the content reception terminal is transmitting / receiving content. Stores distribution status information indicating whether or not
Distribution status determination means for determining whether or not the distribution status information stored in the storage terminal information storage means indicates that content is not being transmitted / received for each of the terminal information extracted by the storage terminal extraction means; Prepared,
The optimal distribution terminal detection unit is set to detect a content reception terminal of terminal information determined by the distribution state determination unit to indicate that the distribution state information indicates that content is not being transmitted / received. The content distribution server according to claim 1 or 2. The storage terminal information storage means further associates content identification information for identifying content with terminal information indicating the content reception terminal storing the content, and stores the content stored in the content reception terminal. It stores usability information that indicates whether it can be used,
Use availability judgment means for judging whether or not the availability information stored in the storage terminal information storage means indicates that the content can be used for each of the terminal information extracted by the storage terminal extraction means. Further comprising
The optimum distribution terminal detecting means targets the content receiving terminal of the terminal information determined by the availability determining means that the availability information indicates that the content can be used. The content distribution server according to any one of claims 1 to 3.   The terminal information transmitting means transmits terminal information of all content receiving terminals determined as optimal distribution terminals when a plurality of content receiving terminals are determined as optimal distribution terminals by the optimal distribution terminal detecting means. The content distribution server according to any one of claims 1 to 4. Content storage means for associating and storing content identification information for identifying content and the content;
When the terminal information stored in association with the content identification information included in the content distribution request is not stored in the storage terminal information storage unit, the content is associated with the content identification information included in the content distribution request. Content retrieval means for retrieving the content stored in the storage means;
Content transmitting means for transmitting the content extracted by the content extracting means to a content receiving terminal that has requested distribution of the content;
The content distribution server according to any one of claims 1 to 5, further comprising: The content stored in the content receiving terminal is encrypted,
Decryption key storage means for storing content identification information for identifying content and a decryption key for decrypting encrypted content obtained by encrypting the content in association with each other;
Decryption key extraction means for extracting a decryption key stored in the decryption key storage means in association with content identification information included in the decryption key request received from the content receiving terminal;
Decryption key transmitting means for transmitting the decryption key extracted by the decryption key extracting means to the content receiving terminal that has made the decryption key request;
The content distribution server according to any one of claims 1 to 6, further comprising: In a content distribution method performed by a content distribution server connected via a network to a plurality of content receiving terminals that store content,
The storage terminal information storage means for storing the content identification information for identifying the content and the terminal information indicating the content receiving terminal storing the content in association with each other is inquired, and the content received from the content receiving terminal A storage terminal extraction procedure for extracting each terminal information stored in the storage terminal information storage means in association with the content identification information included in the distribution request;
For each of the content receiving terminals, the terminal information storage unit that stores the terminal information indicating the content receiving terminal and the installation position information indicating the installation position connected to the network of the content receiving terminal in association with each other is referred to, and the storage terminal An installation position information extraction procedure for extracting installation position information stored in the terminal information storage means in association with the terminal information for each of the terminal information extracted in the extraction procedure;
The content receiving terminal from which the terminal information is extracted in the storage terminal extraction procedure by using the installation position information of the content receiving terminal that has made the distribution request and each of the installation position information extracted in the installation position information extraction procedure An optimal delivery terminal detection procedure for detecting the content receiving terminal at the shortest installation position relative to the installation position of the content receiving terminal that has made the delivery request from
A terminal information transmission procedure for transmitting the terminal information of the content receiving terminal detected as the optimal distribution terminal in the optimal distribution terminal detection procedure to the content receiving terminal that has requested the distribution of the content;
A content distribution method characterized by comprising: A computer serving as a content distribution server connected via a network to a plurality of content receiving terminals that store content,
The storage terminal information storage means for storing the content identification information for identifying the content and the terminal information indicating the content receiving terminal storing the content in association with each other is inquired, and the content received from the content receiving terminal A storage terminal extraction procedure for extracting each terminal information stored in the storage terminal information storage means in association with the content identification information included in the distribution request;
For each of the content receiving terminals, the terminal information storage unit that stores the terminal information indicating the content receiving terminal and the installation position information indicating the installation position connected to the network of the content receiving terminal in association with each other is referred to, and the storage terminal An installation position information extraction procedure for extracting installation position information stored in the terminal information storage means in association with the terminal information for each of the terminal information extracted in the extraction procedure;
The content receiving terminal from which the terminal information is extracted in the storage terminal extraction procedure by using the installation position information of the content receiving terminal that has made the distribution request and each of the installation position information extracted in the installation position information extraction procedure An optimal delivery terminal detection procedure for detecting the content receiving terminal at the shortest installation position relative to the installation position of the content receiving terminal that has made the delivery request from
A terminal information transmission procedure for transmitting the terminal information of the content receiving terminal detected as the optimal distribution terminal in the optimal distribution terminal detection procedure to the content receiving terminal that has requested the distribution of the content;
A content distribution program characterized by causing

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