JP5348167B2 - Information processing apparatus, information processing method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transmit information showing the location of a device in which the content of an acquisition object is not deleted in response to a query for resolving a domain name in a distribution system in which a DNS is applied to a CDN. <P>SOLUTION: An information processing device performs the steps of: receiving a domain name from a query device; determining whether location information corresponding to the domain name is stored in a list; acquiring location information of a node device which stores contents associated with the domain name and second time information showing a period, or shorter than the period, until the time when the node device deletes the contents, if it is determined that the information is not stored; associating the acquired location information with the acquired second time information and with the received domain name to store them in storage means; prolonging a period shown by first time information corresponding to the domain name, if it is determined that the information is stored; transmitting the location information corresponding to the domain name to the query device; and deleting the corresponding location information from the storage means when the period shown by the first time information elapses. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention relates to a technical field of a distribution system using an overlay network.

  2. Description of the Related Art In recent years, a distribution system is known in which content distributed to a terminal device is distributed and stored in a plurality of server devices, and a content distribution load is distributed to a plurality of server devices. As such a delivery system, there is a CDN (Contents Delivery Network).

  For example, Patent Document 1 describes a technique related to a distributed cache system. In this distributed cache system, the cache server A transmits a content request to the origin server when the content requested from the client terminal is not stored. When the cache control server receives a request for content from the cache server A to the origin server, the cache control server performs control to transfer the content from the cache server B storing the requested content to the cache server A.

JP 2007-66161 A

  Here, it is assumed that DNS (Domain Name System) is applied to the CDN. In this case, the DNS server stores the domain name indicating the content acquisition destination and the IP address (Internet Protocol) of the server device that stores the content in association with each other. Then, the DNS server returns an IP address corresponding to the domain name to be queried in response to the domain name resolution inquiry from the terminal device or the like. As a result, the terminal device requests content from the server device based on the received IP address.

  However, the server device that stores the content deletes the content with the oldest upload date and time from the cache, for example. For this reason, the DNS server may return the IP address of the server device from which the content has been deleted to the terminal device or the like. Then, the server device that has received the content request from the terminal device cannot transmit the content. Alternatively, the server device that has received the request needs to obtain the requested content from another server device. In this case, it takes a long time for the terminal device to acquire the content.

  The present invention has been made in view of the above points. The present invention relates to an information processing apparatus capable of transmitting information indicating the location of an apparatus that has not deleted content to be acquired in response to a domain name resolution inquiry in a distribution system in which DNS is applied to a CDN. It is an object to provide a processing method and a program.

  In order to solve the above-described problem, according to the first aspect of the present invention, content distributed and stored in a plurality of node devices connected to the network is distributed via an overlay network constituted by the plurality of node devices. An information processing apparatus that resolves a domain name from which content is acquired in a distribution system that deletes content stored in the node device that has an older date and time transmitted from the node device. A domain name associated with the content distributed and stored in the plurality of node devices, location information indicating a location of the node device storing the content, and a time until the location information is deleted Storage means for associating and storing the first time information indicating the domain name and the domain name resolution Receiving means for receiving a domain name associated with the content distributed and stored in the plurality of node devices from the inquiry device, and the location information corresponding to the domain name received by the receiving means A first determination unit that determines whether the content is stored in a list, and the content that is associated with the domain name received by the reception unit when the first determination unit determines that the content is not stored; The location information of the node device; and second time information indicating a time equal to or less than a time until the node device indicating the location of the location information deletes the content associated with the domain name received by the receiving unit; The acquisition means for acquiring the location information acquired by the acquisition means, and the first time information by the acquisition means When it is determined that the obtained second time information and the domain name received by the receiving unit are stored in the storage unit in association with each other and the first determination unit stores the second time information , Extending means for extending the time indicated by the first time information corresponding to the domain name received by the receiving means, and transmitting the location information corresponding to the domain name received by the receiving means to the inquiry device A first transmission unit; and a deletion unit that deletes the corresponding location information from the list when the time indicated by the first time information stored in the list has elapsed.

  According to this invention, when the information processing apparatus acquires the location information of the node device that stores the content associated with the received domain name, the information processing apparatus acquires the time until the location information is deleted from the storage unit. The time until the location information is deleted is equal to or shorter than the time until the node device storing the content deletes the content. Then, the information processing apparatus stores the domain name, the acquired location information, and the acquired time. Also, the inquiry device or the like that has received the location information from the information processing device requests the content from the node device that stores the content based on the received location information. On the other hand, the node device transmits the stored content. At this time, since the transmission date and time of the content becomes new, the time until the node device deletes the content is extended. That is, it is ensured that the content once transmitted by the node device is stored for a certain period of time. In contrast, the information processing apparatus extends the time until the location information transmitted to the inquiry apparatus is deleted from the storage means. Accordingly, the location information stored in the information processing apparatus is deleted before the node apparatus deletes the content. Therefore, it is possible to transmit the location information of the node device that has not deleted the content to be acquired.

  In the invention according to claim 2, when it is determined that the extension unit is stored by the first determination unit, the extension unit includes the first time information corresponding to the domain name received by the reception unit. A predetermined time which is equal to or less than a time from when the node device transmits the content to when the content is deleted is set.

  According to the present invention, when the location information of the node device storing the content is transmitted, a predetermined time is set as the time until the location information is deleted. For this reason, it is not necessary to adjust the extension time, and the time until the location information is deleted can be easily extended.

  According to a third aspect of the present invention, the inquiry device is a device that resolves a domain name, and the receiving means resolves a domain name associated with content stored in a distributed manner in the plurality of node devices. If the inquiry target domain name is received from the inquiry device that has received the inquiry, and the first determination unit determines that the domain name is stored, the first transmission unit receives the domain received by the reception unit The location information corresponding to the name, and the third time information indicating a time equal to or less than the time indicated by the first time information extended by the extension means as the time until the location information is deleted by the inquiry device Are transmitted.

  According to the present invention, when the location information associated with the domain name is returned to the inquiry device that resolves the domain name, the time until the inquiry device deletes the received location information is returned. This time is equal to or shorter than the time for the information processing apparatus to delete the location information from the storage means. That is, the time is less than or equal to the time until the node device storing the content deletes the content. Therefore, the location information stored in the inquiry device is deleted from the inquiry device before the node device deletes the content. Therefore, the inquiry device can transmit the location information of the node device that has not deleted the content to be acquired to the inquiry source device.

  The invention according to claim 4 is a second storage means for storing number information indicating the number of the location information transmitted by the first transmitting means in association with the domain name received by the receiving means; A second determination unit that determines whether the number indicated by the number information corresponding to the domain name received by the reception unit is greater than a first predetermined number, and the first determination unit determines that the number is not stored; Or if the second determination means determines that the number is greater than the first predetermined number, the command information indicating the storage instruction of the content associated with the domain name received by the reception means A second transmission means for transmitting to the node device, wherein the acquisition means is determined to be not stored by the first determination means, or is determined by the second determination means. If it is judged that the more than a predetermined number, and acquires the location information of the destination of the node device of the command information by the second transmission means.

  According to the present invention, the content associated with a domain name having a larger number of location information transmissions is a content that is requested more frequently from the overlay network. According to this invention, when the number of location information transmissions corresponding to the received domain name is greater than a predetermined number, any node device stores the content associated with the domain name. This increases the number of node devices that store the content associated with the domain name. Therefore, since the number of node devices that store content that is frequently requested to the overlay network increases, it is possible to distribute the processing load of the node device for content requests.

  According to a fifth aspect of the present invention, the inquiry device is a device that resolves a domain name, and the receiving unit resolves a domain name associated with content that is distributed and stored in the plurality of node devices. The domain name received by the receiving unit is received when the domain name of the query target is received from the querying device that received the query, and the first transmitting unit determines that the first determining unit stores the domain name. The location information corresponding to the name, and the third time information indicating a time equal to or less than the time indicated by the first time information extended by the extension means as the time until the location information is deleted by the inquiry device And the location corresponding to the domain name received by the receiving means is determined to be stored by the first determining means. The apparatus further comprises third determination means for determining whether the number of reports is equal to or less than a second predetermined number, and the first transmission means is determined by the third determination means to be equal to or less than the second predetermined number. The third time information indicating a shorter time than the case where it is determined that it is not less than the second predetermined number is transmitted.

  According to the present invention, when the location information associated with the domain name is returned to the inquiry device that resolves the domain name, the time until the inquiry device deletes the received location information is returned. At this time, when the number of node devices that store the content associated with the domain name is small, a short time is returned as the time until the inquiry device deletes the location information. Therefore, since the inquiry device deletes the location information in a short time, the frequency with which the information processing device is inquired about the resolution of the same domain name increases. As a result, the number of pieces of location information corresponding to the domain name is increased from the information processing apparatus. Therefore, when the number of node devices that store content is small, the number of node devices that store content can be increased quickly.

  The invention according to claim 6 is a distribution system in which content stored in a distributed manner in a plurality of node devices connected to a network is distributed via an overlay network constituted by the plurality of node devices, An information processing method in an information processing apparatus for resolving a domain name from which content is acquired, in a distribution system in which content transmitted from the node apparatus is deleted among contents stored in the node apparatus, A reception step of receiving a domain name associated with content distributed and stored in the plurality of node devices from an inquiry device that inquires about name resolution; and the location corresponding to the domain name received in the reception step A configuration in which information is distributed and stored in the plurality of node devices. The domain name associated with the content, the location information indicating the location of the node device storing the content, and the first time information indicating the time until the location information is deleted are stored in association with each other as a list A determination step for determining whether it is stored in the list stored in the storage means, and a content associated with the domain name received in the reception step when it is determined that it is not stored in the determination step The location information of the node device that stores the location information, and a time that is equal to or less than the time until the node device that indicates the location of the location information deletes the content associated with the domain name received in the reception step. Two-hour information, an acquisition step for acquiring, the location information acquired in the acquisition step, As the first time information, the second time information acquired in the acquisition step and the domain name received in the reception step are associated with each other and stored in the storage means, and stored in the determination step. If it is determined that the domain name received in the reception step, the extension step of extending the time indicated by the first time information corresponding to the domain name received in the reception step, and the location corresponding to the domain name received in the reception step A transmission step of transmitting information to the inquiry device; and a deletion step of deleting the corresponding location information from the list when the time indicated by the first time information stored in the list has elapsed. Features.

  The invention according to claim 7 is a distribution system in which content distributed and stored in a plurality of node devices connected to a network is distributed via an overlay network configured by the plurality of node devices, In a distribution system in which content that has been transmitted from the node device is deleted among the content stored in the node device, the domain name is stored in a computer included in the information processing device that resolves the domain name from which the content is acquired. A receiving step of receiving a domain name associated with content distributed and stored in the plurality of node devices from an inquiry device that inquires about a solution, and the location information corresponding to the domain name received in the receiving step includes , Content stored in a distributed manner in the plurality of node devices The domain name associated with the location information, the location information indicating the location of the node device storing the content, and the first time information indicating the time until the location information is deleted are stored in association with each other as a list A determination step for determining whether the list is stored in the storage means, and a content associated with the domain name received in the reception step when it is determined that the list is not stored in the determination step; The location information of the node device to be stored, and a second time that is less than or equal to the time until the node device whose location information indicates the location deletes the content associated with the domain name received in the receiving step An acquisition step for acquiring time information, the location information acquired in the acquisition step, and the first information As the time information, the second time information acquired in the acquisition step and the domain name received in the reception step are associated with each other and stored in the storage means, and stored in the determination step. If it is determined that there is an extension step for extending the time indicated by the first time information corresponding to the domain name received in the reception step, and the location information corresponding to the domain name received in the reception step. A transmission step of transmitting to the inquiry device; and a deletion step of deleting the corresponding location information from the list when the time indicated by the first time information stored in the list has elapsed. And

  According to the present invention, when acquiring the location information of the node device that stores the content associated with the received domain name, the information processing device acquires the time until the location information is deleted from the storage unit. The time until the location information is deleted is equal to or shorter than the time until the node device storing the content deletes the content. Then, the information processing apparatus stores the domain name, the acquired location information, and the acquired time. Also, the inquiry device or the like that has received the location information from the information processing device requests the content from the node device that stores the content based on the received location information. On the other hand, the node device transmits the stored content. At this time, since the transmission date and time of the content becomes new, the time until the node device deletes the content is extended. That is, it is ensured that the content once transmitted by the node device is stored for a certain period of time. In contrast, the information processing apparatus extends the time until the location information transmitted to the inquiry apparatus is deleted from the storage means. Accordingly, the location information stored in the information processing apparatus is deleted before the node apparatus deletes the content. Therefore, it is possible to transmit the location information of the node device that has not deleted the content to be acquired.

It is a figure showing an example of outline composition of a distribution system of one embodiment. It is a figure which shows the operation | movement outline | summary of the delivery system S of one Embodiment. (A) is a block diagram showing a schematic configuration example of a DNS server for CDN SC, and (B) is a block diagram showing a schematic configuration example of a node. It is a flowchart which shows the process example of the control part 1 of the DNS server SC for CDN in one Embodiment. It is a flowchart which shows the process example of the control part 11 of the node in one Embodiment.

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

[1. Overview of distribution system configuration and operation]
First, the configuration and operation outline of the distribution system of the present embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a schematic configuration example of a distribution system according to the present embodiment. The distribution system S is a CDN to which DNS is applied. As shown in FIG. 1, the distribution system S of this embodiment includes a center server SS, a Web server SW, a DNS server SDi (i = 1, 2, 3... P), a CDN DNS server SC, and a node device. Nn (n = 1, 2, 3... K) or the like. The node device Nn is hereinafter referred to as “node”. The center server SS, Web server SW, DNS server SDi, CDN DNS server SC and nodes are connected to the network NW. The network NW is composed of the Internet or the like.

  As shown in FIG. 1, in the distribution system S, a base network NLn is constructed for each of a plurality of bases Pn. Examples of the base include a karaoke store, a school, a company, a house, and other facilities. The base network NLn is a private network such as a LAN (Local Area Network) as a communication means.

  Each base network NLn is connected to a node and a plurality of base terminals Tn-l (l = 1, 2, 3,... J). The node has a function as an edge server that provides content to the base terminal Tn-l connected to the same base network NLn. On the other hand, the base terminal Tn-l has a function of reproducing content. For example, when the base Pn is a karaoke store, the base terminal Tn-l is a commander that plays content for karaoke. For example, when the base Pn is a school, it is a viewing terminal that reproduces content for teaching materials. For example, when the base Pn is a company, it is a viewing terminal that reproduces content for training. For example, when the base Pn is a house, it is a set-top box that reproduces content for a broadcast program.

  The Web server SW is a server device for delivering a Web page to the base terminal Tn-1. The DNS server SDi and the DNS server for CD SC are DNS servers that resolve domain names. The plurality of DNS servers SDi include an authority of a predetermined domain and a DNS server that accepts only domain name resolution queries from the base terminal Tn-l. An authority is a DNS server that manages information related to subdomains included in a predetermined domain in the DNS. The DNS server for CDN SC is a domain authority corresponding to the distribution system S. Specifically, the CDN DNS server SC manages information related to an acquisition destination of content distributed in the distribution system S. The actual acquisition destination of the content distributed in the distribution system S is a node. The CDN DNS server SC is an example of an information processing apparatus according to the present invention. The DNS server SDi and the base terminal Tn-l are examples of the inquiry device according to the present invention.

  Further, as shown in FIG. 1, in the distribution system S, an overlay network ON is configured by participation of a plurality of nodes that can communicate with each other via a network NW. The overlay network ON is a logical network that forms a virtual link. The overlay network ON is realized by a specific algorithm, for example, an algorithm using a distributed hash table. The distributed hash table is hereinafter referred to as “DHT (Distributed Hash Table)”. Here, participating in the overlay network ON means operating in a state in which various messages can be transmitted to and received from other nodes via the overlay network ON based on a routing table using DHT. Note that a routing table using DHT is known in Japanese Patent Application Laid-Open No. 2006-197400 and the like, and thus detailed description thereof is omitted. A node ID is assigned to each node participating in the overlay network ON. This node ID is unique identification information for identifying a node among nodes participating in the overlay network ON.

  In the distribution system S, various contents are distributed and stored in a plurality of nodes. Each content is given a content ID. The content ID is unique identification information for identifying the content from the content stored in the overlay network ON. The center server SS inputs content into the overlay network ON. The input of content means that the content is stored in any node and the stored content can be acquired from the overlay network ON by each node. Attribute information such as content ID and title of each content is described in the content catalog information. The content catalog information is created by the center server SS. Then, the center server SS distributes the content catalog information to all nodes.

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

  A certain node may acquire content from the holding node via the overlay network ON. Here, the node that acquires the content is hereinafter referred to as a “user node”. The user node searches the overlay network ON for the location of the holding node that stores the content. Specifically, the user node transmits a search message. The search message is a message for inquiring about the location of the content to be acquired to the root node of the content. The search message includes the content ID of the content to be acquired. The root node acquires index information corresponding to the content ID included in the received search message from the index information cache. The root node returns the acquired index information to the user node that is the source of the search message. Thereby, the user node receives the IP address and the like of the holding node from the root node. Then, the user node accesses the holding node and downloads the content. Note that the process of inquiring the location of the content to the root node is well known in, for example, Japanese Patent Application Laid-Open No. 2007-053662, and detailed description thereof is omitted.

  When the user node acquires content from the holding node, the user node publishes the content. The disclosure of content means that the content acquired by the user node can be acquired from the overlay network ON. Specifically, the user node stores the acquired content. Then, the user node transmits a publish message to the root node. The publish message is a message for notifying the root node that the content has been saved. The publish message includes the content ID of the saved content and the node information of the user node that saved the content. The root node stores index information including a set of content ID and node information included in the received publish message in the index information cache. In this way, the user node becomes a new holding node for storing content.

  Each holding node deletes the content when the last access date and time of the stored content becomes old. The last access date and time is the date and time when the stored content was last uploaded from the holding node to another node or the base terminal T1-1. If the stored content has never been uploaded, the last access date / time is the date / time when the content was stored. The reason for deleting the content having the oldest access date and time is to increase the capacity for storing other content by deleting the content that is not so often used. Specifically, when the holding node acquires content, the holding node stores the acquired content in association with the content deletion time. The content deletion time is the remaining time until the content is deleted. When the content deletion time has elapsed, the holding node deletes the corresponding content. Specifically, the content deletion time decreases with time. When the content deletion time reaches 0, the content is deleted. The initial value of the content deletion time is determined in advance. The holding node sets an initial value for the content deletion time when the content is acquired and stored and when the content is uploaded. Therefore, when a content is uploaded, the holding node extends the remaining time until the content is deleted. Note that the holding node may refer only to the last access date or the last access time of the content. In other words, the holding node may delete the content with the oldest last access date or last access time. Specifically, the holding node deletes the corresponding content when a predetermined number of days elapses from the last access date. This predetermined number of days corresponds to the content deletion time. Alternatively, the holding node deletes the corresponding content when the content deletion time has elapsed from the last access time.

[2. Domain name resolution and content distribution]
Next, with reference to FIG. 2, the domain name resolution by the CDN DNS server SC and the distribution of contents to the base terminal Tn-l in the distribution system S will be described. FIG. 2 is a diagram showing an outline of the operation of the distribution system S of the present embodiment.

  A node list is stored in the CDN DNS server SC. The node list is information for resolving subdomains included in the domain corresponding to the distribution system S. As shown in FIG. 2, a plurality of node records are registered in the node list. The node record is information corresponding to an A type resource record in DNS. Each node record stores a domain name, an IP address, a content ID, a record deletion time, and the like.

  The domain name stored in the node record is the domain name of the subdomain included in the domain corresponding to the distribution system S. This domain name is given a different name for each content, for example. That is, a domain name associated with content distributed in the distribution system S exists for each content. For example, it is assumed that the content ID is a 4-digit decimal number. In this case, the content ID itself may be converted into a character string. For example, when the content ID is “0123”, the domain name is “0123”. At this time, the fully qualified domain name (FQDN) is “0123.xxxxx.yy.zz”. Here, “xxxxx.yy.zz” is the domain name of the domain corresponding to the distribution system S. In the node record, FQDN may be stored as a domain name.

  The IP address stored in the node record is the IP address of the holding node that stores the content associated with the domain name. As described above, when the last access date and time of stored content becomes old, the holding node deletes the content. The node record registered in the node list does not include the node record of the node from which the content once saved is deleted. In other words, it is ensured that the IP address of the node that still stores the content is registered in the node list. The reason will be described later. The IP address is an example of location information in the present invention.

  The content ID stored in the node record is the content ID of the content associated with the domain name. Note that when the content ID is included in the domain name itself, it is not necessary to store the content ID separately from the domain name.

  The record deletion time is the remaining time until the node record is deleted. The record deletion time corresponds to TTL (Time To Live) of a resource record in DNS. When the record deletion time elapses, the node record is deleted. Specifically, the record deletion time decreases with time. When the record deletion time reaches 0, the node record is deleted. The record deletion time is set to be equal to or less than the corresponding content deletion time. The content deletion time corresponding to the record deletion time is the content associated with the domain name stored in the node record among the contents stored by the node corresponding to the IP address stored in the node record. Content deletion time. The record deletion time is an example of first time information in the present invention.

  A certain base terminal Tn-l, for example, the base terminal T1-1 acquires content. For example, the base terminal T1-1 accesses the Web server SW and acquires an HTML (HyperText Markup Language) document. Then, the base terminal T1-1 displays a web page based on the acquired HTML document. At this time, the base terminal T1-1 acquires the domain name of the content to be played back within the Web page from, for example, an HTML document. This domain name is described in predetermined tags such as an object tag and an embed tag. For example, it is assumed that “0123.xxxxx.yy.zz” is described as the domain name. That is, the content to be played back is content whose content ID is “0123”. This content is called content A. Therefore, the base terminal T1-1 transmits a name resolution request message (FIG. 2 (1)). The name resolution request message is a message for inquiring about domain name resolution. The name resolution request message includes “0123.xxxxx.yy.zz” as the domain name to be queried. The base terminal T1-1 transmits a name resolution request message to the DNS server for CD SC or any DNS server SDi. Which DNS server is transmitted depends on the setting of the base terminal T1-1. Here, it is assumed that the base terminal T1-1 transmits a name resolution request message to the DNS server SD1.

  It is assumed that the DNS server SD1 does not cache the resource record corresponding to “0123.xxxxx.yy.zz”. In this case, the DNS server SD1 inquires about resolution of the domain name to other DNS servers. Here, it is assumed that an iterative mode in DNS is used as an inquiry method. In this case, the DNS server SD1 finally makes an inquiry to the authority of the domain indicated by “xxxxx.yy.zz” included in the name resolution request message. Accordingly, the DNS server SD1 transfers the name resolution request message received from the base terminal T1-1 to the DNS server SC for CDN (FIG. 2 (2)).

  The DNS server SC for CDN acquires “0123”, which is the domain name of the subdomain, from the domain name included in the received name resolution request message. Then, the DNS server SC for CDN searches for a resource record with “0123”. That is, the CDN DNS server SC searches for the IP address of the node that stores the content A whose content ID is “0123” (FIG. 2 (3)).

  At this time, it is assumed that no node record storing “0123” as the domain name is registered in the node list. In this case, the DNS server SC for CDN acquires the IP address of the node that stores the content A. Specifically, the CDN DNS server SC randomly determines a node for newly storing the content A, for example. For example, it is assumed that the CDN DNS server SC determines the node N1 as a node for storing content. Then, the DNS server SC for CDN acquires the IP address of the determined node. The DNS server for CDN SC stores the IP address of each node in advance. Then, the DNS server for CDN SC transmits a content storage request message to the node N1 based on the acquired IP address (FIG. 2 (4A-1)). The content storage request message is a message requesting to store content. The content storage request message includes the content ID of the content to be stored. In this case, “0123” that is the content ID of the content A is included as the content ID. The content storage request message is an example of command information in the present invention.

  The node N1 acquires content A corresponding to the content ID included in the received content storage request message from the center server SS or another node. Then, the node N1 stores the content A. Then, the node N1 sets, for example, 24 hours as the content deletion time of the content A as an initial value (FIG. 2 (4A-2)). When the content storage request message is transmitted, the CDN DNS server SC newly registers the node record of the node N1 in the node list. At this time, the DNS server for CDN SC acquires the initial value of the record deletion time of the node record to be registered. The initial value of the record deletion time is stored in advance in the DNS server SC for CDN. The initial value of the record deletion time is set to a value equal to or less than the initial value of the content deletion time. For example, the DNS server for CDN SC acquires 24 hours. Then, the DNS server SC for CDN registers a node record including “0123” as the domain name, the IP address of the node N1, and 24 hours as the initial value of the record deletion time. (FIG. 2 (4A-3)).

  Next, the DNS server for CDN SC returns the IP address of the node N1 determined as the node for storing the content A to the DNS server SD1 (FIG. 2 (5)). Specifically, the DNS server SC for CDN transmits a name resolution response message including the resource record of the node N1. The resource record is generated using information stored in the node record. Specifically, the resource record includes “0123” as the domain name, the IP address of the node N1, the TTL of the resource record, and the like. The TTL of the resource record is a value equal to or shorter than the record deletion time of the node record registered in the node list. For example, 20 hours is set in TTL.

  On the other hand, it is assumed that the DNS server SC for CDN finds one or more node records, for example, as a result of searching for a node record storing the content A. In this case, the DNS server SC for CDN selects any one of the found node records. For example, the DNS server SC for CDN selects the node record of the node N1. Next, the CDN DNS server SC extends the record deletion time of the node record of the selected node N1 (FIG. 2 (4B)). For example, the DNS server for CDN SC sets the initial value of 24 hours as the record deletion time of the node record. Then, the DNS server for CDN SC returns a name resolution response message including the resource record of the selected node N1 to the DNS server SD1 (FIG. 2 (5)). At this time, a value equal to or shorter than the extended record deletion time is set in the TTL of the resource record. For example, 20 hours is set in TTL. Note that TTL is an example of third time information in the present invention.

  The DNS server SD1 caches the resource record included in the received name resolution response message (FIG. 2 (6)). Then, the DNS server SD1 transmits the received name resolution response message to the base terminal T1-1 (FIG. 2 (7)). The base terminal T1-1 acquires the IP address of the node N1 from the resource record included in the received name resolution response message. Further, the base terminal T1-1 acquires “0123” that is the content ID from the domain name of the content A. Then, the base terminal T1-1 transmits a content transmission request message to the node N1 based on the acquired IP address (FIG. 2 (8)). The content transmission request message is a message requesting content upload. The content transmission request message includes “0123” that is the content ID of the content to be uploaded. The node N1 uploads the content A corresponding to the content ID included in the received content transmission request message to the base terminal T1-1 ((9) in FIG. 2). Further, the node N1 extends the content deletion time of the content A ((10) in FIG. 2). For example, the node N1 sets an initial value of 24 hours as the content deletion time.

  For example, assume that the node N2 stores the content B. Further, it is assumed that a node record including the domain name of the content B and the IP address of the node N2 is registered in the node list of the DNS server for CDN SC. Here, it is assumed that the record deletion time of the node record of the node N2 becomes zero. Accordingly, the DNS server for CDN SC deletes the node record of the node N2 from the node list (FIG. 2 (11)). On the other hand, the content deletion time of the content B stored in the node N2 becomes 0 at almost the same timing. Therefore, the node N2 deletes the content B (FIG. 2 (12)).

  As described above, when the IP address of the node that stores the content corresponding to the domain name to be inquired is not registered, the CDN DNS server SC acquires the IP address of the node that stores the content. In the case of the example of FIG. 2, the DNS server SC for CDN transmits a content storage request message so that any node stores the content. Then, the DNS server SC for CDN returns the acquired IP address. Therefore, the DNS server SC for CDN can return the IP address of the node storing the content in response to the name resolution request message. Also, the CDN DNS server SC registers a node record including the acquired IP address. At this time, the CDN DNS server SC sets a time equal to or shorter than the content deletion time in the node corresponding to the acquired IP address as the record deletion time. Accordingly, the corresponding node record is deleted before the content stored by the node is deleted. In the example of FIG. 2, the initial value of the content deletion time and the initial value of the record deletion time are set to the same value. Therefore, the content stored in the node and the node record registered in the node list are deleted at almost the same timing. Therefore, the DNS server SC for CDN does not return the IP address of the node from which the content has been deleted in response to the name resolution request message. Further, when the IP address of the node that stores the content corresponding to the domain name to be inquired is registered, the CDN DNS server SC returns the IP address. At this time, the DNS server for CDN SC extends the record deletion time of the node record that stores the returned IP address. The node corresponding to the returned IP address uploads the content corresponding to the domain name. Therefore, the node extends the content deletion time of the uploaded content. The record deletion time after the extension is set to be shorter than the content deletion time after the extension. Therefore, it is possible to extend the time for storing the reply IP address while not replying the IP address of the node from which the content has been deleted. In this way, the DNS server SC for CDN can transmit the IP address of the node from which the content to be acquired by the base terminal Tn-l has not been deleted.

  Further, the DNS server for CDN SC returns a resource record including the IP address to the DNS server SDi. At this time, the CDN DNS server SC sets a time equal to or shorter than the extended record deletion time as the TTL of the resource record. Therefore, the resource record received by the DNS server SDi is deleted from the cache of the DNS server SDi until the content stored in the node is deleted. Therefore, the DNS server SDi can transmit the IP address of the node from which the content targeted for acquisition by the base terminal Tn-l has not been deleted.

  Note that the CDN DNS server SC may be controlled so that the number of nodes storing the content corresponding to the domain name increases in accordance with the number of IP address replies. The higher the frequency of inquiries about resolution for a certain domain name, the higher the frequency at which the base terminal Tn-l is requested from the node for the content corresponding to that domain name. Therefore, by increasing the number of nodes that store content that is requested frequently, the processing load of the nodes for the requests is distributed. Specifically, the number of IP address replies per unit time is set in each node record. Each time the CDN DNS server SC returns an IP address in response to the name resolution request message, it updates the number of replies per unit time of the returned IP address. When the number of replies per unit time exceeds a predetermined number set in advance, the CDN DNS server SC transmits a content storage request message to any one of the nodes. This content storage request message includes the content ID of the content corresponding to the domain name to be queried. Accordingly, the number of nodes storing contents corresponding to the domain name to be inquired increases. The number of IP address replies per unit time is an example of number information in the present invention. The specified number is an example of a first predetermined number in the present invention.

  Further, the DNS server SC for CDN may shorten the time indicated by the TTL included in the resource record to be returned, as the number of node records storing the domain name to be inquired is smaller. The DNS server SDi deletes the resource record received from the DNS server for CDN from the cache in a shorter time as the time indicated by the TTL is shorter. For this reason, the DNS server SDi transmits the name resolution request message to the DNS server SC for CDN more frequently as the time indicated by the TTL is shorter. This increases the possibility that the number of IP address replies per unit time exceeds the specified number. Therefore, when the number of nodes storing content is small, the number of nodes storing content can be increased quickly. Specifically, when the number of node records storing the domain name to be queried is equal to or less than a predetermined number, the CDN DNS server SC sets a time shorter than that when the number is larger than the predetermined number as the TTL. The predetermined number in this case is an example of a second predetermined number in the present invention.

[3. Configuration of DNS server for CDN]
Next, the configuration of the CDN DNS server SC will be described with reference to FIG. FIG. 3A is a block diagram illustrating a schematic configuration example of the DNS server SC for CDN. As shown in FIG. 3A, the CDN DNS server SC includes a control unit 1, a storage unit 2, a communication unit 3, and the like. The control unit 1, the storage unit 2, and the communication unit 3 are connected to each other via a bus 4.

  The storage unit 2 is composed of, for example, a hard disk drive. The storage unit 2 stores various programs such as an operating system and a DNS server program. The DNS server program may be downloaded from a predetermined server on the network NW, for example. In addition, the DNS server program may be recorded on a recording medium such as a DVD (Digital Versatile Disc) and read through a drive of the recording medium.

  The storage unit 2 stores node information of each node. The storage unit 2 stores a node list in which node records are registered. Further, the storage unit 2 stores various setting values such as an initial value of the record deletion time and an initial value set in the TTL of the resource record.

  The communication unit 3 performs communication control with a node or the like through the network NW. The control unit 1 includes a CPU having a calculation function, a working RAM, a ROM, and the like. The control unit 1 reads and executes a program stored in the storage unit 2 or the like by the CPU, so that the first determination unit, the acquisition unit, the control unit, the extension unit, the first transmission unit, the deletion unit, the first unit in the present invention. 2 determination means, second transmission means and third determination means.

[4. Node configuration]
Next, the configuration and function of the node will be described with reference to FIG. FIG. 3B is a block diagram illustrating a schematic configuration example of a node. As shown in FIG. 3B, the node includes a control unit 11, a storage unit 12, a communication unit 13a, a communication unit 13b, a buffer memory 14, and the like. The control unit 11, the storage unit 12, the communication unit 13 a, the communication unit 13 b, and the buffer memory 14 are connected to each other via a bus 15.

  In the present embodiment, the node is a relay device that relays an IP (Internet Protocol) packet between the network NW and the base network NLn. This relay device is, for example, a router or an L3 switching hub. The node may be a terminal device used by the user. In addition, the node may basically be a device such as a gateway that is regularly connected to the network NW.

  The storage unit 12 is composed of, for example, a hard disk drive. The storage unit 12 stores an operating system, a P2P program, and the like. The P2P program is a program for communicating with other nodes using a routing table. In addition, the storage unit 12 stores a routing table using DHT used for overlay network ON. The storage unit 12 stores content catalog information distributed from the center server SS. Further, the storage unit 12 stores content acquired from the overlay network ON, a content ID, and a content deletion time in association with each other. The storage unit 12 stores index information. The storage unit 12 stores the IP address and port number of the center server SS.

  The communication unit 13a performs communication control with other nodes, the CDN DNS server SC, the center server SS, and the like through the network NW. The communication unit 13b performs communication control with the base terminal Tn-l through the base network NLn. Further, the buffer memory 14 temporarily accumulates the content received via the communication unit 13a.

  The control unit 11 includes a CPU having a calculation function, a working RAM, a ROM, and the like. The control unit 11 has a clock function and a timer function. And the control part 11 controls each part of a node centrally, when CPU reads and runs the program memorize | stored in the memory | storage part 12 grade | etc.,.

[5. Operation of distribution system]
Next, the operation of the distribution system S in the present embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a flowchart illustrating a processing example of the control unit 1 of the CDN DNS server SC in the present embodiment.

  The process shown in FIG. 4 is started, for example, when the power of the CDN DNS server SC is turned on. First, the control unit 1 determines whether or not the power supply OFF is requested by the administrator of the distribution system S (step S1). At this time, if the control unit 1 determines that the power-off is not requested (step S1: NO), the control unit 1 subtracts the record deletion time of each node record registered in the node list (step S2). For example, the control unit 1 acquires the elapsed time from when the previous record deletion time was subtracted by the clock function. Then, the control unit 1 subtracts the elapsed time from the record deletion time stored in each node record. Next, the control unit 1 determines whether there is a node record whose record deletion time is 0 or less (step S3). At this time, when the control unit 1 determines that there is a node record whose record deletion time is 0 or less (step S3: YES), all the node records whose record deletion time is 0 or less are listed in the node list. (Step S4). The node record may be deleted from the node list. Therefore, the node record deleted from the node list may remain stored in the storage unit 2.

  When it is determined that there is no node record whose record deletion time has become 0 or less (step S3: NO), or when the process of step S4 is finished, the control unit 1 or the base terminal Tn-1 or DNS server It is determined whether or not a name resolution request message has been received from SDi (step S5). At this time, when it is determined that the name resolution request message has not been received (step S5: NO), the control unit 1 proceeds to step S1.

  On the other hand, if it is determined that the name resolution request message has been received (step S5: YES), the control unit 1 acquires the domain name from the name resolution request message. And the control part 1 searches the node record which stores the acquired domain name from a node list (step S6). Next, the control unit 1 determines whether there is a node record that stores the acquired domain name (step S7).

  At this time, if it is determined that there is no node record (step S7: NO), the control unit 1 determines a node for storing the content (step S8). For example, the control unit 1 may determine at random. Next, the control unit 1 transmits a content storage request message to the determined node (step S9). Specifically, the control unit 1 acquires the determined node IP address from the storage unit 2. In addition, the control unit 1 acquires the content ID from the domain name acquired from the name resolution request message. Then, the node transmits a content storage request message including the acquired content ID based on the acquired IP address. Next, the control unit 1 registers a node record in the node list (step S10). Specifically, the control unit 1 uses the domain name acquired from the name resolution request message, the IP address of the node determined as the node for storing the content, the initial value T1 as the record deletion time, and the number of replies per unit time. Register a node record that stores 0. The initial value T1 is a value indicating a time equal to or shorter than the initial value of the content deletion time.

  Next, the control unit 1 generates a resource record to be returned (step S15). Specifically, the control unit 1 generates a resource record including the domain name acquired from the name resolution request message, the IP address acquired from the registered node record, and the initial value T2 as TTL. The initial value T2 is a value indicating a time shorter than the initial value T1. Next, the control unit 1 transmits a name resolution response message including the generated resource record to the transmission source of the name resolution request message (step S16).

  In step S7, if it is determined that there is a node record including the acquired domain name (step S7: YES), the control unit 1 acquires the number of replies per unit time of the corresponding node record. Then, the control unit 1 determines whether or not the number of replies per unit time exceeds a specified number (step S11). At this time, when there are a plurality of corresponding node records, the control unit 1 determines whether or not the number of replies per unit time stored in each node record exceeds the specified number. Alternatively, the control unit 1 may determine whether or not the average value of the number of replies per unit time stored in each node record exceeds a specified number. At this time, if the control unit 1 determines that the number of replies per unit time exceeds the specified number (step S11: YES), the control unit 1 proceeds to step S8. That is, the control unit 1 transmits a content storage request message to any node, registers a node record, transmits a name resolution response message, and the like.

  In step S11, when the control unit 1 determines that the number of replies per unit time does not exceed the specified number (step S11: NO), is the number of searched corresponding node records equal to or greater than 2? It is determined whether or not (step S12). At this time, if it is determined that the retrieved number is not 2 or more (step S12: NO), the record deletion time of the corresponding node record is extended (step S13). Specifically, the control unit 1 sets an initial value T1 for the record deletion time. Next, the control unit 1 updates the number of replies per unit time of the corresponding node record (step S14). Next, the control unit 1 generates a resource record to be returned (step S15). At this time, the control unit 1 stores the IP address stored in the retrieved node record in the resource record. Next, the control unit 1 transmits a name resolution response message including a resource record (step S16).

  In step S12, when it is determined that the number of searched corresponding node records is 2 or more (step S12: YES), the control unit 1 selects one of the corresponding node records (step S17). ). For example, the control unit 1 may select at random. In addition, the control unit 1 may select a node record having the shortest record deletion time, or may select a node record having the longest record deletion time. Further, the control unit 1 may select a node record having the smallest number of replies per unit time. Next, the control unit 1 extends the record deletion time of the selected node record (step S18). Specifically, the control unit 1 sets an initial value T1 for the record deletion time. Next, the control unit 1 updates the number of replies per unit time of the corresponding node record (step S19).

  Next, the control unit 1 determines whether or not the number of searched corresponding node records is equal to or less than a predetermined number (step S20). At this time, when it is determined that the searched number is equal to or less than the predetermined number (step S20: YES), the control unit 1 generates a resource record to be returned (step S15). At this time, the control unit 1 stores the IP address stored in the selected node record in the resource record. Further, the control unit 1 sets an initial value T2 as TTL. On the other hand, if the control unit 1 determines that the searched number is not less than or equal to the predetermined number (step S20: NO), it generates a resource record to be returned (step S21). At this time, the control unit 1 stores the IP address stored in the selected node record in the resource record. Moreover, the control part 1 sets initial value T3 as TTL. The initial value T3 is a value that is longer than the initial value T2 and indicates a time that is less than or equal to the initial value T1. When finishing the process of step S15 or S21, the control unit 1 transmits a name resolution response message including a resource record (step S16).

  After finishing the process of step S16, the control part 1 transfers to step S1. In step S1, if the control unit 1 determines that the power-off is requested (step S1: YES), the control unit 1 ends the process shown in FIG.

  FIG. 5 is a flowchart illustrating a processing example of the control unit 11 of the node in the present embodiment. The process shown in FIG. 5 is started, for example, when the power of the node is turned on. First, the control unit 11 determines whether or not the administrator of the site Pn has requested power OFF (step S51). At this time, when it is determined that the power supply OFF is not requested (step S51: NO), the control unit 11 determines whether a content transmission request message has been received from the base terminal Tn-1 (step S52). ). At this time, when the control unit 11 determines that the content transmission request message has been received (step S52: YES), the control unit 11 proceeds to step S54. On the other hand, when it is determined that the content transmission request message has not been received (step S52: NO), the control unit 11 determines whether a content storage request message has been received from the DNS server SC for CDN (step S52). S53). At this time, when it is determined that the content storage request message has been received (step S53: YES), the control unit 11 proceeds to step S54. On the other hand, if the control unit 11 determines that the content storage request message has not been received (step S53: NO), the control unit 11 proceeds to step S51.

  In step S54, the control unit 11 acquires a content ID from the received message (step S54). Next, the control unit 11 determines whether or not the content corresponding to the acquired content ID is stored in the storage unit 12 (step S55). At this time, the control unit 11 determines that the content is stored. If so (step S55: YES), the process proceeds to step S58. On the other hand, when determining that the content is not stored (step S55: NO), the control unit 11 acquires the content corresponding to the acquired content ID from the overlay network ON (step S56). At this time, if any node stores the content, the control unit 11 acquires the content from the node. On the other hand, the control unit 11 acquires the content from the center server SS when no node stores the content. Next, the control unit 11 stores the content acquired from the overlay network ON, the content ID acquired from the message, and the initial value of the content deletion time in the storage unit 12 in association with each other (step S57). When the control section 11 finishes the process step of step S57, the control section 11 proceeds to step S58.

  In step S58, the control unit 11 determines whether or not the received message is a content storage request message. At this time, if the control unit 11 determines that the message is not a content storage request message (step S58: NO), the control unit 11 proceeds to step S51. On the other hand, if the control unit 11 determines that the content storage request message is received (step S58: YES), the control unit 11 selects the content corresponding to the content ID acquired from the content storage request message as the base of the transmission source of the content storage request message. Uploading to the terminal Tn-l (step S59). Next, the control unit 11 extends the content deletion time of the uploaded content (step S60). Specifically, the control unit 11 sets an initial value for the content deletion time corresponding to the uploaded content. Note that when the content is acquired from the overlay network ON and stored (steps S56 and S57), the control unit 11 may omit the process of step S60. This is because the initial value is set in step S57.

  After finishing the process of step S60, the control part 11 transfers to step S51. In step S51, when it is determined that the power supply is requested to be turned off (step S51: YES), the control unit 11 ends the process illustrated in FIG.

  In the above embodiment, the content ID is included in the domain name associated with the content distributed from the distribution system S. However, the content ID may not be included in the domain name. For example, the storage unit 12 of the CDN DNS server SC may store a correspondence table indicating the content ID of each content and the domain name in association with each other. When registering the node record, the DNS server for CDN SC acquires the content ID associated with the domain name included in the name resolution request message from the correspondence table. Then, the DNS server SC for CDN registers a node record that stores the domain name included in the name resolution request message and the content ID acquired from the correspondence table.

  A plurality of contents may be associated with one domain name. For example, the upper digit of the content ID may be included in the domain name. For example, it is assumed that “012” is included in the domain name. In this case, ten contents with content IDs “0120” to “0129” are associated with the domain name. Alternatively, in the correspondence table, a plurality of content IDs may be associated with one domain name. Here, a plurality of contents associated with one domain name is referred to as a “content group”. In this case, each node needs to store content in units of content groups. This is because it is not known which content is requested from the base terminal Tn-l among the content groups corresponding to the domain name included in the name resolution request message received by the DNS server for CDN. Specifically, the DNS server SC for CDN acquires the content ID of each content constituting the content group based on, for example, the domain name included in the name resolution request message. Next, the DNS server for CDN SC transmits a content storage request message including the acquired plurality of content IDs to any of the nodes. The node acquires each content constituting the content group based on a plurality of content IDs included in the content storage request message. In the HTML document distributed from the Web server SW, for example, a domain name and a content ID associated with the content to be reproduced are described. When acquiring the content, the base terminal Tn-l transmits a content transmission request message including the content ID described in the HTML document to the node.

  In the above embodiment, when the DNS server for CDN SC transmits a content storage request message to a node and registers a node record, an initial value for a predetermined record deletion time is set. However, the CDN DNS server SC may acquire the content deletion time from the node to which the content storage request message is transmitted. For example, when a node that has received a content storage request message acquires content and stores the content in association with the content deletion time, the node transmits the content deletion time to the DNS server for CDN SC. The DNS server for CDN SC may set the received content deletion time as it is in the node record as the record deletion time. Alternatively, the CDN DNS server SC may calculate the record deletion time by subtracting a predetermined value from the received content deletion time or by dividing by a predetermined value. That is, the CDN DNS server SC may acquire a time shorter than the received content deletion time as the record deletion time.

  Further, when the node record for storing the domain name to be inquired is not registered, the CDN DNS server SC may inquire the overlay network ON for a node that stores the content associated with the domain name. For example, the CDN DNS server SC transmits a search message including the content ID acquired from the domain name to the root node. Then, the CDN DNS server SC receives the index information from the root node. As a result, the CDN DNS server SC acquires the IP address of the node that stores the content associated with the domain name to be inquired. Next, the CDN DNS server SC inquires of each node that stores the content associated with the domain name to be inquired about the content deletion time. Specifically, the DNS server SC for CDN transmits a deletion time inquiry message including the content ID acquired from the domain name. The node transmits the content deletion time corresponding to the content ID included in the received deletion time inquiry message to the DNS server for CDN SC. Thereby, the DNS server SC for CDN can acquire content deletion time. Then, the DNS server for CDN SC registers a node record of each node that stores the content associated with the domain name to be inquired.

  Moreover, in the said embodiment, the node apparatus of this invention was applied to the router and the L3 switching hub. However, the node device of the present invention may be applied to a network device having a function of relaying information, such as a proxy server, a load balancer, and a web accelerator. The node device of the present invention may be applied to a server device such as a cache server or an edge server.

  Moreover, in the said embodiment, although the peer to peer network using DHT was applied to the overlay network, it is not restricted to this. For example, another peer-to-peer system or a system using an overlay network may be applied. As a peer-to-peer system that does not use DHT, for example, there is a hybrid peer-to-peer system.

DESCRIPTION OF SYMBOLS 1,11 Control part 2,12 Storage part 3,13a, 13b Communication part SC DNS server DNS server Nn node NW network ON Overlay network S Distribution system

Claims (7)

Content distributed and stored in a plurality of node devices connected to a network is distributed via an overlay network composed of the plurality of node devices, and the content stored in the node devices In the distribution system in which the date and time transmitted from the node device is deleted,
An information processing apparatus that resolves a domain name from which content is acquired,
A domain name associated with the content distributed and stored in the plurality of node devices, location information indicating the location of the node device storing the content, and a time until the location information is deleted Storage means for associating and storing one-hour information as a list;
Receiving means for receiving a domain name associated with content distributed and stored in the plurality of node devices from an inquiry device that inquires about resolution of a domain name;
First determination means for determining whether the location information corresponding to the domain name received by the reception means is stored in the list;
If it is determined by the first determination means that the information is not stored, the location information of the node device that stores the content associated with the domain name received by the reception means and the location information indicate the location Acquisition means for acquiring second time information indicating a time equal to or less than a time until the node device deletes the content associated with the domain name received by the reception means;
The location information acquired by the acquisition means, the second time information acquired by the acquisition means as the first time information, and the domain name received by the reception means are associated with each other and stored. Control means stored in the means;
An extension means for extending the time indicated by the first time information corresponding to the domain name received by the receiving means when it is determined that the information is stored by the first determining means;
First transmitting means for transmitting the location information corresponding to the domain name received by the receiving means to the inquiry device;
Deleting means for deleting the corresponding location information from the list when the time indicated by the first time information stored in the list has elapsed;
An information processing apparatus comprising:   If it is determined that the extension means is stored by the first determination means, the extension means transmits the content to the first time information corresponding to the domain name received by the reception means. The information processing apparatus according to claim 1, wherein a predetermined time that is equal to or less than a time until content is deleted is set. The inquiry device is a device for resolving a domain name;
The receiving means receives the domain name to be queried from the inquiry device that has received an inquiry about the resolution of the domain name associated with the content distributed and stored in the plurality of node devices,
When it is determined by the first determination means that the information is stored, the first transmission means deletes the location information corresponding to the domain name received by the reception means and the inquiry device deletes the location information. The third time information indicating a time equal to or less than the time indicated by the first time information extended by the extension means is transmitted as the time until Information processing device. Second storage means for storing number information indicating the number of the location information transmitted by the first transmission means in association with the domain name received by the reception means;
Second determining means for determining whether the number indicated by the number information corresponding to the domain name received by the receiving means is greater than a first predetermined number;
When it is determined by the first determination means that it is not stored, or when it is determined by the second determination means that the number is greater than the first predetermined number, it is associated with the domain name received by the reception means Second transmission means for transmitting command information indicating a command to store the received content to any of the node devices;
Further comprising
The acquisition means is determined by the second transmission means when it is determined by the first determination means that it is not stored, or when it is determined by the second determination means that the number is greater than the first predetermined number. The information processing apparatus according to claim 1, wherein the location information of the node device that is a transmission destination of command information is acquired. The inquiry device is a device for resolving a domain name;
The receiving means receives the domain name to be queried from the inquiry device that has received an inquiry about the resolution of the domain name associated with the content distributed and stored in the plurality of node devices,
The first transmission means deletes the location information corresponding to the domain name received by the reception means and the inquiry device, when it is determined that the first transmission means is stored by the first determination means And the third time information indicating a time equal to or less than the time indicated by the first time information extended by the extension means,
A third determination for determining whether the number of the location information corresponding to the domain name received by the receiving means is equal to or less than a second predetermined number when it is determined that the information is stored by the first determination means; Further comprising means,
The first transmission means indicates a shorter time when the third determination means determines that the second predetermined number or less is less than the second predetermined number or less than the second predetermined number. The information processing apparatus according to claim 4, wherein the information is transmitted for 3 hours. Content distributed and stored in a plurality of node devices connected to a network is distributed via an overlay network composed of the plurality of node devices, and the content stored in the node devices In the distribution system in which the date and time transmitted from the node device is deleted,
An information processing method in an information processing apparatus that resolves a domain name from which content is acquired,
A receiving step of receiving a domain name associated with content distributed and stored in the plurality of node devices from an inquiry device that inquires about resolution of a domain name;
The location information corresponding to the domain name received in the receiving step indicates a domain name associated with content stored in a distributed manner in the plurality of node devices, and a location of the node device storing the content. A determination step of determining whether the location information and the first time information indicating the time until the location information is deleted are stored in the list stored in the storage unit in association with each other and stored as a list;
The location information of the node device that stores the content associated with the domain name received in the reception step and the node in which the location information indicates the location when it is determined that the location information is not stored in the determination step An acquisition step of acquiring second time information indicating a time equal to or less than a time until the device deletes the content associated with the domain name received in the reception step;
The location information acquired in the acquisition step, the second time information acquired in the acquisition step as the first time information, and the domain name received in the reception step are associated with each other and stored. Control steps stored in the means;
An extension step of extending the time indicated by the first time information corresponding to the domain name received in the reception step when it is determined that the information is stored in the determination step;
Transmitting the location information corresponding to the domain name received in the receiving step to the inquiry device;
A deletion step of deleting the corresponding location information from the list when the time indicated by the first time information stored in the list has elapsed;
An information processing method comprising: Content distributed and stored in a plurality of node devices connected to a network is distributed via an overlay network composed of the plurality of node devices, and the content stored in the node devices In the distribution system in which the date and time transmitted from the node device is deleted,
The computer included in the information processing device that resolves the domain name of the content acquisition destination
A receiving step of receiving a domain name associated with content distributed and stored in the plurality of node devices from an inquiry device that inquires about resolution of a domain name;
The location information corresponding to the domain name received in the receiving step indicates a domain name associated with content stored in a distributed manner in the plurality of node devices, and a location of the node device storing the content. A determination step of determining whether the location information and the first time information indicating the time until the location information is deleted are stored in the list stored in the storage unit in association with each other and stored as a list;
The location information of the node device that stores the content associated with the domain name received in the reception step and the node in which the location information indicates the location when it is determined that the location information is not stored in the determination step An acquisition step of acquiring second time information indicating a time equal to or less than a time until the device deletes the content associated with the domain name received in the reception step;
The location information acquired in the acquisition step, the second time information acquired in the acquisition step as the first time information, and the domain name received in the reception step are associated with each other and stored. Control steps stored in the means;
An extension step of extending the time indicated by the first time information corresponding to the domain name received in the reception step when it is determined that the information is stored in the determination step;
Transmitting the location information corresponding to the domain name received in the receiving step to the inquiry device;
A deletion step of deleting the corresponding location information from the list when the time indicated by the first time information stored in the list has elapsed;
A program characterized by having executed.

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