JP4735371B2 - Distribution system, control device, control device program, management device, management device program, auxiliary device, auxiliary device program, and distribution system control method - Google Patents

Description

  The present application belongs to the technical fields of distribution system, control device and control device program, management device and management device program, auxiliary device and auxiliary device program, and distribution system control method. System for distributing content (distribution information) such as a movie via a distribution system, a distribution system control method, a control device and a control device program, a management device and a management device program, and an auxiliary device and an auxiliary device program included in the distribution system Belongs to the technical field.

  In recent years, so-called content distribution in which a terminal device accesses a server or the like storing the above content via a network such as the Internet, and distributes the content desired to be viewed on the terminal device to the terminal device. Research and development is thriving.

  Here, the basic configuration of a conventional distribution system that distributes the content is a server that stores the content from the terminal device that desires the distribution of the content via the network as exemplified in Patent Document 1 below, for example. The terminal device receives the distribution of the desired content, that is, the transmission of the content after establishing the connection.

  On the other hand, in recent years, there is a so-called P2P (Peer to Peer) grid type distribution system (hereinafter simply referred to as a distribution system) as another configuration of the distribution system that performs the content distribution. Here, the distribution system is a distribution system that distributes the content using the network, and content data corresponding to the content is directly exchanged between terminal devices belonging to the network ( In other words, it is a distribution system in which content is shared among a plurality of terminal devices, and all the terminal devices subscribing to the distribution system have functions as the server and receive distribution of the content This is a distribution system that also has a function as a device (in the following description, the terminal device is simply referred to as a node).

  In the distribution system, when a content distribution is to be received at a certain node, the node identifies other nodes storing content data corresponding to the content desired to be distributed on the network. Referring to information (hereinafter, this information is simply referred to as index information), which is a pair of node identification information for identifying the content and content identification information for identifying the content from other content, It is necessary to receive distribution of desired content from the node indicated by the node identification information.

  Therefore, in a general distribution system, as exemplified in Patent Document 2 below, for example, the index information related to one or a plurality of contents is collectively stored (distributed storage) in a plurality of nodes, and this is stored in the distribution system. It is configured to be referenced from a node that receives content distribution. More specifically, for example, when the network constituting the distribution system is the Internet, search information (for example, a title name of a movie) that can specify content desired to be distributed and the IP of the node storing the search information It is necessary to recognize a pair with an (Internet Protocol) address and exchange the desired content using the IP address as a clue.

  Accordingly, in a distribution system in which a large number of unspecified nodes such as the above distribution system share content, each node recognizes a set of search information of all content and the IP address of the node storing it. It is necessary to keep it.

  However, when the number of nodes connected to the network increases, the search information of all contents and the nodes storing the contents are stored because of the limitation of the physical recordable amount in each node. It is not realistic for each node to record the IP address of each node (for example, when 1 million nodes are connected to the network, the IP addresses for 1 million nodes are all connected to each other). It's not realistic to record it).

  Also, when each node records search information of all contents and the IP address of the node storing it, the power switch at each node in the network is frequently turned on / off (for example, the node is a personal computer). In the case of realizing the above, the power switch can be frequently operated). However, the IP address and the like recorded in each node are frequently updated, and practically it is difficult to operate the entire network.

  Therefore, in order to deal with the above-described problems, only the minimum necessary node IP address information is recorded, and to other nodes that do not recognize the IP address, messages to be delivered to that node. A distribution system is being researched in which each node records only the minimum necessary index information by transferring it via other nodes, and one of them is a physical network such as the Internet. There is a distribution system that constructs a logical overlay network using a so-called DHT (Distributed Hash Table) and distributes content on the overlay network.

  Next, an outline of the distribution system using the DHT will be described. In the following description, the distribution system will be described focusing on the overlay network, not the physical network.

In the distribution system using the DHT, a node ID (Identification) for identifying each node is assigned to each node on the overlay network. At this time, the node ID is assigned a unique number for each node in the distribution system in which they participate, that is, a number different from other nodes. This number has a number of bits (bit length) that can accommodate the maximum number of nodes in the network. More specifically, for example, when a 128-bit node ID is used, a maximum of 2 ¹²⁸ ≈340 × 10 ³⁶ nodes can be connected in one network. The node ID is generally a hash value for a unique value for each node, such as an IP address assigned to the node itself, a so-called MAC (Media Access Control) address, or a serial number of the node itself. Use the value obtained by applying the function.

  Next, in the distribution system using the DHT, a unique content ID different from other contents on the overlay network is assigned to the content itself distributed by the distribution system as the corresponding content identification information. To do. The bit length of the content ID is also the same as the bit length of the node ID. In general, the content ID includes title data indicating the title of the content, attribute data indicating the attributes of the data constituting the content, data for several bytes from the top of the data configuring the content, and the like. A value obtained by applying a hash function is used.

  Furthermore, in the distribution system using the DHT, even when a node frequently participates in and withdraws from the distribution system (leaves), it is necessary to appropriately distribute the load on each node. Non-Patent Document 1 below discloses a technique for performing load distribution appropriately even in the case where a node frequently participates in and leaves (leaves) a node in the distribution system. Yes.

On the other hand, in the distribution system described above, a plurality of pieces of duplicate data (hereinafter, the duplicate data is simply referred to as a replica) are prepared for one piece of content data corresponding to a certain content. It is known that these replicas are distributed (stored in a distributed manner) among multiple nodes participating in the network, thereby improving the fault tolerance and distribution of access to each content. It has been.
Japanese Unexamined Patent Publication No. 2000-122954 JP 2004-265273 A "Examination of lightweight load balancing method for distributed hash table" The Institute of Electronics, Information and Communication Engineers IEICE technical report

  However, if the above-mentioned replicas are dynamically increased in the distribution system according to, for example, the access frequency and stored in many content holding nodes, the capacity of the storage area of the node storing the index information is limited. Therefore, the storage area is over capacity (that is, the index information cannot be stored any more), and even if the number of replicas is increased, the access load to these replicas cannot be further distributed. Problems arise.

  In addition, when the number of the index information increases, in a node where the number of the index information that can be stored is not so large, the index information corresponding to the content having the large distribution request occupies most of the index information stored in the node. As a result, there has been a problem that the number of stored index information corresponding to contents that are not so popular (in other words, the number of distribution requests is not large) decreases.

  And this problem is that if you want to distribute content that is not very popular (in other words, content that is not popular but has a non-zero distribution request), the corresponding index information can be found in the distribution system As a result, there is a problem that the distribution of the content may be hindered.

  Therefore, the present invention has been made in view of the above-mentioned problems, and the problem is that the content corresponding to the index information becomes undeliverable by reducing the number of stored index information of unpopular content. , A distribution system and a distribution system control method capable of contributing to improvement of convenience and distribution efficiency as a distribution system, a control device and a control device program included in the distribution system, a management device and a management device A program, an auxiliary device, and a program for the auxiliary device are provided.

In order to solve the above-mentioned problem, the invention according to claim 1 is configured such that a plurality of node devices are connected via a network, and distribution information stored in any one of the node devices is stored. In order to identify a main distribution system that distributes to any other node device, distribution information identification information for identifying the distribution information, and a storage device that is the node device that stores the distribution information A distribution system comprising: an auxiliary device comprising auxiliary storage means for storing distribution information location information including the storage device identification information; and an auxiliary system comprising a management device comprising management means for managing the auxiliary device. a system, the main distribution system, a node device for managing the location of the distribution information, said comprising the location information storing means for storing the delivery information location information Includes over de device, the location of the distribution information is managed by the identification information having a value equal or closest value to the value of the distribution information identification information for identifying the distribution information is given the node device The auxiliary storage means is capable of storing a larger number of distribution information location information than the number of distribution information location information that can be stored in the location information storage means, and further the main distribution system. Is based on the number of pieces of distribution information location information corresponding to the specific distribution information that is one piece of the distribution information among the distribution information location information stored in the location information storage means. Including a control device that is the node device including auxiliary request information output means for outputting auxiliary request information for requesting auxiliary participation in the main distribution system to the management means. Said management means that the value of the control device identification information for identifying the controller, when equal to the value of the distribution information identification information for identifying the specific delivery information, with respect to the value of the distribution information identification information And generating means for generating identification information having the most recently large value or the most recently small value, and the node device to which identification information equal to the identification information generated by the generating means is already provided in the main distribution system. If the node device to which the identification information equal to the identification information and the identification information equal to the identification information are not already present in the main distribution system, the identification information is sent to the auxiliary device. Instructions for allocating to the auxiliary device, instructing the auxiliary device to participate in the main distribution system, and for causing the auxiliary device to manage the location of the specific distribution information in the main distribution system. Indicating means .

  In order to solve the above problem, the invention described in claim 2 is a control device included in the main distribution system described in claim 1, and includes the request information output unit.

In order to solve the above-described problem, the invention according to claim 3 is configured to output the auxiliary request information to the management unit when the number of pieces of distribution information location information is equal to or greater than a preset threshold value. Composed.

In order to solve the above-described problem, the invention according to claim 4 is the control device according to claim 2 or 3, wherein the specific delivery is performed when the auxiliary device participates in the main delivery system. When the number of pieces of distribution information location information corresponding to the information is less than a predetermined threshold, output the request information for requesting to release the participating auxiliary device from the main distribution system to the management means. It further includes a withdrawal request information output means.

  In order to solve the above-mentioned problems, a fifth aspect of the present invention is a management device included in the auxiliary system according to the first aspect, and includes the management unit.

In order to solve the above problem, the invention according to claim 6 is the management device according to claim 5, wherein the management means has a value of control device identification information for identifying the control device, wherein Generating means for generating identification information having a value closest to the value of the distribution information identification information or a value closest to the value of the distribution information identification information when equal to the value of the distribution information identification information for identifying the specific distribution information; Confirmation means for confirming whether or not the node device to which identification information equal to the identification information generated by the means is already present in the main distribution system is provided, and identification information equal to the identification information is assigned When the node device does not already exist in the main distribution system, the identification information is allocated to the auxiliary device, and the auxiliary device is instructed to participate in the main distribution system. , And a instruction means for managing the location of the specific distribution information in the auxiliary device the main distribution system to.

In order to solve the above-described problem, the invention according to claim 7 is the management device according to claim 6, wherein the management means includes the auxiliary device participating in the main distribution system. When obtaining withdrawal request information requesting that the participating auxiliary device be detached from the main distribution system, a separation instruction for transmitting separation instruction information to the effect that the auxiliary device is to be detached from the main distribution system. Information transmission means is further provided .

In order to solve the above problem, an invention described in claim 8 is an auxiliary device included in the auxiliary system described in claim 1, and includes the auxiliary storage unit .

In order to solve the above-mentioned problem, the invention according to claim 9 is the auxiliary device according to claim 8, wherein the distribution information location information in the auxiliary storage means is stored in the location information storage means. The distribution information location information is configured to be at least twice the storable number .

In order to solve the above-described problem, the auxiliary device according to claim 8 or 9, wherein when participating in the main distribution system, the distribution control information necessary for distributing the specific distribution information is the distribution information. An acquisition unit that acquires distribution control information including location information from any of the node devices in the main distribution system; and the acquired distribution control information is stored in the auxiliary storage unit to store the specific distribution information. Storage control means for distribution .

In order to solve the above problems, the invention according to claim 11, a computer included in any of the node devices in the main distribution system according to claim 1 or one of claims 2 4 single Function as the control device described in the section.

In order to solve the above-described problem, the invention according to claim 12 is the computer according to any one of claims 5 to 7 , wherein the computer included in the management device in the auxiliary system according to claim 1 is used. It functions as a management means.

In order to solve the above problem, the invention according to claim 13 is the computer according to any one of claims 8 to 10 , wherein the computer included in the auxiliary device in the auxiliary system according to claim 1 is used. To function as an auxiliary device.

In order to solve the above problem, the invention according to claim 14 is configured such that a plurality of node devices are connected via a network, and distribution information stored in any one of the node devices is stored. , to identify the main distribution system for distributing one of the other said node device, and the distribution information identification information for identifying the distribution information, which is a said node device that stores the distribution information storage device delivery comprising a storage device identification information, and an auxiliary device provided with an auxiliary storage means for storing distribution information location information including a said auxiliary device management apparatus including a managing means for managing, and an assistant system makes the The main distribution system is a node device that manages the location of the distribution information, and includes a location information storage unit that stores the distribution information location information. The location of the distribution information is managed by the node device to which identification information having a value equal to or closest to the value of the distribution information identification information for identifying the distribution information is provided. The auxiliary storage means is a distribution executed in the distribution system capable of storing a larger number of distribution information location information than the number of distribution information location information that can be stored in the location information storage means. The system control method, wherein the control device which is the node device corresponds to the specific distribution information which is one of the distribution information in the distribution information location information stored in the location information storage unit based on the number of information location information, the auxiliary request information output Engineering for outputting an auxiliary request information to the management means for requesting an auxiliary participation in the main distribution system of the auxiliary device If, when the management means acquires the supplementary request information, the value of the control device identification information for identifying the control device is equal to the value of the distribution information identification information for identifying the specific distribution information, the The node device to which identification information having a value that is most recently large or a value that is most recently small with respect to the value of the distribution information identification information is generated, and to which the identification information equal to the generated identification information is assigned If the node device does not already exist in the main distribution system, the identification information is allocated to the auxiliary device, and the main distribution system is assigned to the auxiliary device. And instructing the auxiliary device to manage the location of the specific distribution information in the main distribution system .

As described above, according to the invention described in claim 1 or 14 , in the distribution information location information stored in the location information storage means, it corresponds to the specific distribution information which is one of the distribution information. Auxiliary request information is output to the management means based on the number of the distribution information location information, and an auxiliary device having a larger number of storable distribution information location information than the node device in the main distribution system in response to the auxiliary request information. Since it participates in the main distribution system, in the node device belonging to the main distribution system, other distribution information caused by the increase in the number of distribution information location information corresponding to the distribution information due to the concentration of distribution requests for the distribution information. A reduction in the number of stored corresponding distribution information location information can be prevented. Further, according to the first aspect of the present invention, the management means that has acquired the assistance request information uses a value for the control device identification information for identifying the control device as a distribution for identifying the specific distribution information. When the value of the information identification information is equal, the node device is provided with identification information having a value that is most recently large or a value that is most recently small with respect to the value of the distribution information identification information. Is not already present in the main distribution system, the identification information is allocated to the auxiliary device, the auxiliary device is instructed to participate in the main distribution system, and the auxiliary device is instructed to the main distribution system. Since the location of the specific distribution information is managed, the auxiliary device can participate in the main distribution system more quickly and smoothly.

According to the invention described in claim 2 or 11 , the distribution information corresponding to the specific distribution information which is the one distribution information among the distribution information location information stored in the location information storage means. The auxiliary request information is output to the management means based on the number of location information, and the auxiliary device in which the number of storable distribution information location information can be stored by the management device in response to the auxiliary request information is larger than the node device in the main distribution system. Since it is allowed to participate in the distribution system, in the node device belonging to the main distribution system, due to the concentration of distribution requests for the distribution information, the distribution information location information corresponding to the distribution information increases. A reduction in the number of stored corresponding distribution information location information can be prevented.

Furthermore, according to the invention described in claim 5 or 12 , the management means that has acquired the assistance request information uses a value of control device identification information for identifying the control device to identify the specific distribution information. When the value of the distribution information identification information is equal to the value of the distribution information identification information, the identification information having the latest large value or the latest small value is generated, and the identification information equal to the identification information is given. When the node device does not already exist in the main distribution system, the identification information is allocated to the auxiliary device, the auxiliary device is instructed to participate in the main distribution system, and the auxiliary device is instructed to the main distribution system. Since the location of the specific distribution information in the distribution system is managed, the auxiliary device can participate in the main distribution system more quickly and smoothly .

Furthermore, according to the invention described in claim 8 or 13 , the distribution corresponding to the specific distribution information which is one of the distribution information in the distribution information location information stored in the location information storage means. Based on the number of information location information, under the management of the management device, an auxiliary device having more storable distribution information location information than the node device in the main distribution system participates in the main distribution system, and therefore belongs to the main distribution system. In the node device, a reduction in the number of stored distribution information location information corresponding to other distribution information due to an increase in the number of distribution information location information corresponding to the distribution information due to concentration of distribution requests for the distribution information is prevented. it can.

Therefore, according to the invention described in each of claims 1, 2, 5, 8 , 11 to 14 , the other distribution information corresponding to the distribution information location information is distributed by reducing the storage number of the distribution information location information. It is possible to prevent the situation from being disabled, and to contribute to improvement of convenience and distribution efficiency in the main distribution system.

According to the third aspect of the invention, in addition to the effect of the second aspect of the invention, the auxiliary request information is output when the number of pieces of distribution information location information is equal to or greater than a threshold value. Alternatively, it is possible to efficiently perform cooperation between the main distribution system and the auxiliary system by determining based on the number of pieces of duplicate information.

According to the invention described in claim 4, in addition to the effect of the invention described in claim 2 or 3, when the number of the distribution information location information corresponding to the specific distribution information is less than a predetermined threshold, Since the withdrawal request information for requesting the auxiliary device participating in the main distribution system to be detached from the main distribution system is output to the management means, the distribution of the auxiliary device is performed when the distribution status of the specific distribution information is improved. By leaving the system, it is possible to return to the state of the original main distribution system and to make the auxiliary system stand by in preparation for the subsequent deterioration of the distribution status.

According to the invention described in claim 6, in addition to the effect of the invention described in claim 5, the management means that has acquired the assistance request information has a value of control device identification information for identifying the control device. When the value of the distribution information identification information for identifying the specific distribution information is equal to the value of the distribution information identification information, the identification information having the most recently large value or the most recently small value is generated. When the node device to which the identification information equal to is not already present in the main distribution system, the identification information is allocated to the auxiliary device, and the auxiliary device is allowed to participate in the main distribution system. Instructing the auxiliary device to manage the location of the specific distribution information in the main distribution system allows the auxiliary device to participate in the main distribution system more quickly and smoothly .

According to the invention described in claim 7 , in addition to the effect of the invention described in claim 6 , withdrawal request information for requesting that the auxiliary device participating in the main delivery system is detached from the main delivery system. Since the withdrawal instruction information indicating the withdrawal from the main distribution system is transmitted to the auxiliary device, the auxiliary device participating in the main distribution system can be quickly returned to the management device management. .

According to the ninth aspect of the invention, in addition to the effect of the eighth aspect of the invention, the storable number of distribution information location information in the auxiliary storage means can be stored in the distribution information location information in the location information storage means. Since the number is at least twice the number, an auxiliary device having a sufficient function for improving the distribution state of the specific distribution information in the main distribution system can participate in the main distribution system.

According to the invention described in claim 10 , in addition to the effect of the invention described in claim 8 or 9 , when participating in the main distribution system, the distribution control information is acquired from any node device in the main distribution system. Since the acquired distribution control information is stored in the auxiliary storage means for distribution of the specific distribution information, the auxiliary device can participate in the main distribution system in a simple and quick process, and the characteristic distribution information can be immediately distributed. Can be provided.

  Next, the best mode for carrying out 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 the delivery system that delivers the content using a network such as the Internet.

Initially the principle of (I) the present invention, before the specifically described embodiments of the present invention, per the principles of the present invention, by referring to outline of a distribution system according to the embodiment.

(A) Overview of Distribution System First, an overview of a distribution system according to an embodiment will be described with reference to FIGS. 1 and 2. 1 and 2 are schematic diagrams showing an outline of the distribution system.

  In general, in the distribution system using the DHT described above, the node and content in the distribution system are identical to each other in relation to the fact that the corresponding node ID and content ID are expressed with the same bit length. It can be considered as being scattered on a ring-like virtual ID space. That is, as shown in FIG. 1A in which one node is displayed with ● and one content is displayed with ○, the ring Rc to which the content belongs and the ring Rn to which the node belongs are virtually concentrically assumed. Further, if it is defined that the value of each ID increases counterclockwise in each ring Rc and Rn, it can be assumed that each node or each content exists without overlapping on each ring Rc and Rn. If each ID is expressed in 128-bit length as in the above example, the number of digits becomes too large. In FIG. 1A, for simplicity of explanation, the bit length of each ID is set to 32 bits. Expressed (the same applies hereinafter). Then, as described above, due to the use of the hash function in determining the value of each ID, each node and each content exist in a substantially distributed manner on each of the above rings Rc and Rn. Become.

  On the other hand, in the distribution system using the DHT, “a node that manages content to which a certain content ID is assigned is a node to which a node ID having a value closest to the value of the content ID is assigned”. ing.

  Here, “near” may be any definition as long as it is consistent in various provisions related to the distribution system. Specifically, for example, “a value that does not exceed the value of the content ID”. And having the smallest difference between values as IDs ”.

  More specifically, for example, as illustrated in FIG. 1A, a node having a node ID value “A0334055” and a node having a node ID value “A03340FF” are adjacent to each other on the ring Rn. If it exists, the content ID value “A0334080” is managed by the node whose node ID value is “A0334055”. In FIG. 1A, the terminal information for managing the content of “◯” is indicated by an arrow extending from each “◯”. In this way, various contents can be managed by being distributed among a large number of nodes.

  At this time, “management” does not mean that the content assigned with the content ID is recorded therein, but recognizes the location of the node where the content is recorded (for example, an IP address). It means that The node where the content is actually recorded may be different from the managed node, or the content to be managed may be recorded in the managed node.

  The above-described content management node is referred to as a “root node”. The root node records the index information including at least a pair of a content ID indicating the content that is to be managed and an IP address of a node in which the content indicated by the content ID is recorded, This is recorded so that it can be referred to from other nodes in the distribution system. In some cases, the index information includes the title of the content, the attribute (genre), and the like.

  In addition, when the content IDs indicating different contents are close to coincidence, and there is no other node having a node ID close to that value, a plurality of indexes corresponding to a plurality of contents by one root node Information will be recorded. Furthermore, when the same content is recorded in a plurality of different nodes and the node recording the same content is close to one root node by chance, The index information of a plurality of nodes each recording content is recorded. An example of the index information EX in the root node described above is shown in FIG.

  Further, a node that actually records each content itself is referred to as a “content holder”. At this time, since the content holder itself is essentially a node, the node ID exists on the ring Rn in FIG.

  Next, in the distribution system using the DHT, the DHT (routing table) itself, which is one of the devices for eliminating the necessity for each node to record the IP addresses of all the nodes as described above, will be described. To do.

  In the DHT according to the embodiment, the ID space illustrated in FIG. 1 is subdivided while increasing the number of levels for each stepped level (for example, in the case of level 1, the ID space is divided into four). Routing information that describes a pair of a node ID of an arbitrary node and its IP address is described for each area (for each area subdivided in stages). For example, when the distribution source inquiry information for requesting the content distribution source information is transferred to the root node in which the index information is recorded, the inquiry information is transferred to the target root node while referring to the routing information. To do. That is, every time the level in DHT increases, the node ID of the routing destination matches the node ID of the root node to be reached one digit at a time, and the request information finally reaches the root node to be reached. Will do.

  In the distribution system using DHT, the inquiry information (query) as described above, distribution request information for requesting distribution of the content itself, a public message described later, and the like are simply referred to as “message”. When the DHT having the above-described mechanism is used, the message can be efficiently transferred to the target node in the ID space as illustrated in FIG. In the following description, when a new content is recorded in the content holder, the message generated in the content holder is referred to as a public message so that it can be discovered (published) from other nodes. A message transmitted from a requester described later to a root node or a cache node described later is referred to as a distribution source inquiry message.

  Here, as described above, since the value of the node ID of the root node is closest to the value of the node ID of the content holder that manages the content by the root node, the distribution source inquiry message is the distribution request. Immediately before the content holder requested by the message is reached, the root node that manages the content to be distributed is reached. Then, the root node that has received the distribution source inquiry message returns the IP address of the content holder storing the content requested by the distribution source inquiry message to the transmission source of the distribution source inquiry message. That is, from the index information (see FIG. 1B) recorded in the root node, the title indicating the content requested by the distribution source inquiry message, the attribute information, and the IP of the node as its content holder The address or the like is returned to the node that is the source of the distribution source inquiry message. By utilizing such DHT, the location of the desired content can be efficiently recognized at the distribution request source, for example. The node that is the content distribution request source described above is hereinafter referred to as a “requester”.

  Next, a description will be given of content registration processing when new content is accumulated in a certain node.

  When new content is stored in a node, that is, the content holder of the content, the content holder will publish that the content has been stored to other nodes in the distribution system.

  That is, when new content is stored in a certain node, the node serving as a content holder for the stored content calculates a content ID corresponding to the content based on the title of the stored content.

  Next, the content holder transmits a public message with a node having a node ID having the same value as the calculated content ID as a destination (regardless of whether or not a node having the node ID actually exists). This public message includes a title indicating the content, attribute information, an IP address of the node as the content holder, and the like, and is transmitted to the node as the destination of each level via each routing destination according to the description of the DHT. Sequentially transferred.

  Then, when the node having the closest node ID is reached, the node recognizes that there is no node in the ID space to which the public message is to be forwarded afterwards ( Recognizing that the node to be transferred is itself), at this point, the node to which the public message has reached becomes the root node for managing new content. Then, the node that becomes the root node records the content ID included in the public message, the IP address indicating the content holder, the attribute information, and the like as index information EX illustrated in FIG. 1B.

  Next, the concept of “cache node” in the distribution system according to the embodiment will be described with reference to FIG. In FIG. 2 and FIG. 3 to be described later, the root node is indicated by a double circle, the content holder is indicated by a circle marked with “X”, and the requester is indicated by a circle marked with “|” inside, which will be described later. A cache node is indicated by a circle with + in the inside, and other general nodes are indicated by a circle.

  When the distribution source inquiry message QRmsg from the requesters RQ1 to RQ3 is transferred to the root node RN (or content holder CH) by the routing using the DHT described above, the transfer route (in FIGS. 2A and 2B) 2 (a) is a route similar to the route followed by the public message PUBmsg described above (shown by a solid line in FIGS. 2 (a) and 2 (b)) as shown in FIG. 2 (a). If the index information EX exemplified in FIG. 1B is also recorded in each node on the path (indicated by reference numeral CN in FIG. 2A), it corresponds to the distribution source inquiry message QRmsg passing through the path. Before the delivery source inquiry message QRmsg arrives at the destination route node RN or content holder CH. It is possible to return the answer corresponding to the distribution source query message QRmsg to the requester RQ1 or RQ3.

  That is, requesters RQ1 to RQ3 that request distribution of content published in the distribution system transmit a distribution source inquiry message QRmsg requesting the IP address of the node (that is, content holder CH) in which the content is recorded. Then, the distribution source inquiry message QRmsg is transferred to the routing destination described in the DHT in each node and approaches the root node RN. Finally, the route merges with the route of the public message PUBmsg from the content holder CH, and reaches the root node RN.

  Here, when the path on the ring Rc shown in FIG. 2A is replaced with a tree structure, it becomes as shown in FIG. 2B, and this is generally called a “spanning tree”.

  The term “spanning tree” is a term originally used in the router technology for preventing the connection of the IP router from forming a loop, but even in the case shown in FIG. One transfer path tree that cannot be defined can be defined for each content ID (not shown in FIG. 2B), but a spanning tree including all nodes participating in the distribution system at that time is described. be able to).

  On the other hand, as shown in FIG. 2A, the route of the distribution source inquiry message QRmsg transmitted from each requester RQ and the route of the public message PUBmsg transmitted from the content holder CH are either Eventually at the node. Therefore, the index information EX included in the public message PUBmsg is recorded in a temporary recording area that can be temporarily recorded at each node on the path for reaching the public message PUBmsg for public release to the root node RN ( That is, the public message PUBmsg is transferred (temporarily cached). Then, the reply to the distribution source inquiry message QRmsg from the requester RQ is sent before the distribution source inquiry message QRmsg reaches the root node RN from the node where the distribution source inquiry message QRmsg arrives on the route to the root node RN. It can be done. A node that is a node other than the root node RN and temporarily stores the index information EX in this manner is hereinafter referred to as a “cache node” CN.

  On the other hand, in the distribution system using the DHT according to the present invention, when the number of contents that can be distributed increases as the number of content holders CH participating in the distribution system increases, The corresponding index information EX is stored for each of the root node RN or the cache node CN as seen in the spanning tree illustrated in FIG.

  In addition to this, as illustrated in FIG. 3, index information EX corresponding to a plurality of contents is recorded in each of the root node RN or the cache node CN, and the same content is recorded for each content. Index information EX indicating a plurality of content holders CH that record content is recorded, and the number of index information EX stored in the root node RN or the cache node CN also increases.

  At this time, in the distribution system, when distribution requests for a certain content increase (that is, the content becomes a popular content), an increase in distribution when the number of content holders CH storing the content is small. The demand cannot be met and a delivery delay or a delivery impossible state will occur.

  In order to cope with this, in the distribution system described above, for content for which a large number of distribution requests (including the distribution source inquiry message QRmsg, hereinafter the same) are generated, a copy of the content (a so-called replica) is generated in another node. ) Is distributed in the distribution system so that the distribution request functions are often increased. Also in this case, as illustrated in FIG. 3, the index information EX including different IP addresses for the same content ID further increases.

(B) Principle of the Present Invention Next, the principle of the present invention based on the above-described distribution system will be described with reference to FIG.

  As shown in FIG. 4, the distribution system S according to the present invention has the P2P type as shown in FIG. 4 in order to prepare for the increase in the index information EX including different IP addresses for the same content ID. In addition to the main distribution system SM having the same configuration as the distribution system, as a physical network, messages can be exchanged with the node N or the root node RN participating in the main distribution system SM. Although it is provided, an auxiliary system SP that does not normally participate in the main distribution system SM is provided.

  Then, the auxiliary system SP stores more index information EX (more preferably twice or more) than the storable amount of the index information EX in each node N or root node RN participating in the main distribution system SM. A plurality of helper nodes SN that can be stored, and an auxiliary server SPM that manages participation or withdrawal of the plurality of helper nodes SN in the distribution system SM.

  In this configuration, in the main distribution system SM, distribution requests for specific content (the content ID of the specific content is assumed to be “1234”) increase (that is, the popularity of the specific content increases). When replicas of the specific content are accumulated in a large number of nodes in the main distribution system SM, for example, the index memory CM1 in the root node RN shown in FIG. 4 corresponds to the specific content (content ID = 1234). The index information EX will occupy most of the storage area. As a result, it corresponds to content other than the specific content (in other words, content that is unpopular content and content ID is “88d3” in the index memory CM1 illustrated in FIG. 4). There is less room for the index information EX to be stored. This means that, when viewed from the requester RQ that desires distribution of the unpopular content, a distribution failure such as an opportunity to find the content holder CH that is the distribution source of the unpopular content is impaired. To do.

  Therefore, in the present invention, for the reason described above, for example, when the number of index information EX stored in the index memory CM1 in the root node RN causes an excessive imbalance between contents, the auxiliary server SPM The helper node SN having the index memory CM2 having a larger storable number of index information EX than the node N or the root node RN in the main distribution system SM is temporarily joined in the main distribution system SM. In the distribution system SM, the index information EX corresponding to a wide range of contents is temporarily stored. In addition, by making the node ID of the helper node SN coincide with the content ID of the content where the popularity is concentrated, the helper node SN is newly added to the specific content (content ID = “1234”). Operate as the root node RN.

  The temporary participation of the helper node SN in the main distribution system SM is because the auxiliary server SPM receives the assistance request message RMG from the root node RN in which an excessive imbalance to the content occurs in the index memory CM1. When the auxiliary server SPM that has started and receives the assistance request message RMG transmits a participation instruction message CMG to one of the helper nodes SN, the temporary participation of the helper node SN in the main distribution system SM is actually executed. The

  In this way, by temporarily participating the helper node SN in the main distribution system SM, the helper node SN becomes a new root node RN for the specific content (content ID = “1234”), and an index in the helper node SN. As illustrated in FIG. 4, a large number of index information EX corresponding to the specific content (content ID = “1234”) is stored in the memory CM <b> 2, and it is possible to prevent the occurrence of a distribution failure as described above. It becomes.

(II) Embodiment Next, an embodiment according to the present invention based on the above-described principle will be specifically described with reference to FIGS. Note that, in the distribution system according to the first embodiment described below, for the sake of simplification of description, it is assumed that the cache node CN does not exist in the distribution system.

  First, a schematic configuration of a node according to the embodiment will be described with reference to FIG. FIG. 5 is a block diagram showing a schematic configuration of the node according to the embodiment. In the embodiment, the content holder CH, requester RQ, root node RN, other nodes N, auxiliary server SPM, and helper node SN are basically all the same hardware except for the storage capacity of the index memory CM. Since it has a configuration, an outline of the configuration of a general node N will be described using FIG. 5 as a representative.

  As illustrated in FIG. 5, the node N included in the distribution system according to the embodiment includes a CPU having a calculation function, a working RAM (Random Access Memory), and a ROM (Read Only Memory) that records various data and programs. And the like, and also serves as the index memory CM for recording and storing (storing) content data as the content itself, the DHT and other necessary programs, and storing the index information EX. A storage unit 12 composed of an HDD or the like (the content data is recorded only in the storage unit 12 in the node N as the content holder CH before distribution) and the received content data are temporarily stored. The buffer memory 13 and the encoded video data included in the content data. A decoder unit 14 that decodes data (video information), audio data (audio information), and the like, and performs a predetermined drawing process on the decoded video data and outputs it as a video signal A video processing unit 15, a display unit 16 such as a CRT (Cathode Ray Tube) or a liquid crystal display that displays video based on the video signal output from the video processing unit 15, and the decoded audio data as an analog audio signal. After the D / A (Digital / Analog) conversion, it is amplified by an amplifier or the like and output, a speaker 18 that outputs the audio signal output from the sound processing unit 17 as a sound wave, and the network 8 Communication unit 20 for controlling communication of information with other nodes N, and instructions from respective users And an input unit (for example, a keyboard, a mouse, or an operation panel) 21 that outputs an instruction signal corresponding to the received instruction to the control unit 11. The control unit 11, the storage unit 12, the buffer memory 13, The decoder unit 14 and the communication unit 20 are connected via a bus 22 so as to be able to exchange data with each other.

  Then, when the CPU in the control unit 11 executes various programs recorded in the storage unit 12 or the like, the control unit 11 performs the requester RQ, the root node RN, the content holder CH, the auxiliary server SPM, the helper server SN, or others The overall operation as any one of the general nodes N is controlled in an integrated manner.

  When the node N is a root node RN as a control device according to the present invention, the storage unit 12 functions as a location information storage unit, and the control unit 11 functions as a request information output unit and a withdrawal request information output unit. To do. When the node N is an auxiliary server SPM as a management apparatus according to the present invention, the control unit 11 functions as an identification information setting unit and a leaving instruction information transmission unit. Furthermore, when the node N is a helper node SN as an auxiliary device according to the present invention, the storage unit 12 functions as an auxiliary storage unit, and the control unit 11 functions as an acquisition unit and a storage control unit.

  Next, operations according to the embodiment will be described by dividing into basic common operations as a general node (including a root node RN, a content holder CH, and a requester RQ), a root node RN, an auxiliary server SPM, and a helper node SN. .

(A) General operation as a node First, a general operation as the node N according to the embodiment, that is, a basic common operation as the node N in the main distribution system SM will be described with reference to FIG. FIG. 6 is a flowchart showing a general operation as the node N according to the embodiment, and is executed by the control unit 11.

  As shown in FIG. 6, in the common operation as the node N according to the embodiment, first, the control unit 11 performs an initialization process for starting the node N (step S1), and the main distribution system SM A participation request message for the node N to participate is transmitted to a contact node, which is another node N that acts as an intermediary when the node N participates in the main distribution system SM (step S2). Is awaited (step S3). Then, for some reason that the node N cannot participate in the main distribution system SM (for example, when it is supposed that a fee will be generated when newly joining the main distribution system SM, payment of the fee is not confirmed) Etc.) (step S3; NO), the fact is displayed on the display unit 16 of the node N to notify the user (step S15), and according to the embodiment as the node N End the process.

  On the other hand, if it is determined in step S3 that the node N is permitted to participate in the main distribution system SM (step S3; YES), the routing information valid at that time in the main distribution system SM from the contact node. Is acquired and stored (step S4), and if the newly participating node N stores content that can be distributed to other nodes N in the main distribution system SM, the content is stored as the content holder CH. The public message PUBmsg corresponding to is generated and transmitted into the main distribution system SM (step S5).

  Then, a playback instruction flag (to be described later) and a terminal end instruction flag (to be described later) in the storage unit 12 are initialized to “0”, and distribution is performed in the main distribution system SM to users of the newly participating node N A process for starting a thread for searching and selecting contents that can be received (details of the thread will be described later with reference to FIG. 7) is performed (step S6).

  Here, the reproduction instruction flag is a flag in the control unit 11 that becomes “1” when the user of the node N selects and determines the content desired to be viewed by the input operation performed using the input unit 21. On the other hand, the terminal termination instruction flag is a flag in the control unit 11 that becomes “1” when the user performs an operation to terminate the use of the node N using the input unit 21.

  Then, it waits for each instruction flag to be updated and changed to “1” by processing in the thread, and waits for reception of various messages from other nodes N of the participating main distribution system SM (step S7). , S8; NO).

  When any instruction flag changes or any message is received by the user (step S8; YES), whether or not the reproduction instruction flag is “1”, that is, the content of the user It is confirmed whether or not a distribution request operation has been performed (step S9).

  If it is determined in step S9 that the user has made a distribution request (step S9; YES), the node N will subsequently operate as the requester RQ. The process or the reproduction process after the acquisition is executed (step S13). When the reproduction instruction flag becomes “1”, the content ID of the content selected by the user during the thread processing is stored at the same time, and the discovery / reproduction processing is performed using the content ID.

  After the reproduction of the content is started, the reproduction instruction flag is returned to “0” (step S16), and the process proceeds to step S7 in preparation for the next distribution request.

  On the other hand, if it is determined in step S9 that the process in step S8 is not a distribution request operation by the user (step S9; NO), the process in step S8 is an input operation other than the distribution request operation or reception of another message. Since this is a process, it is confirmed whether or not a message has been received (step S10). If it is a message reception process (step S10; YES), a process corresponding to the received message (specifically, a routing information update process, a message transfer process to another node N, etc.) is performed. (Step S14), the process proceeds to step S7.

  On the other hand, if it is determined in step S10 that no message has been received yet (step S10; NO), then whether or not the previous input operation is an operation to end the operation as the node N. (Step S11). And when the said operation is not performed (step S11; NO), it considers that the invalid operation was made and transfers to the process of said step S8.

  On the other hand, when an operation to end the operation as the node N is performed (step S11; YES), a withdrawal process such as a process of transmitting a withdrawal message to the main distribution system SM is executed (step S12). ), The operation as the node N according to the embodiment is terminated.

  Next, the contents of the thread executed as a part of the process of step S6 will be specifically described with reference to FIG. FIG. 7 is a flowchart showing the contents of the thread.

  Specifically, as shown in FIG. 7, when a thread for content search and selection operation is started, first, a preset search screen for content search is displayed on the display unit 16 as shown in FIG. 7.

  Here, as the search screen, for example, a title column in which the title as the search screen is displayed, a title input column in which the title is input when performing a search using the title of the content, and the content A name input field where the name is entered when searching using the name of the actor or the like who is performing as a clue, and a name input field where the name is input when searching using the name of the director of the content as a clue And a keyword input field in which the keyword is input when searching using a keyword indicating the content as a clue, a search operation button operated when searching for content using the input search condition, and others An information display field for displaying various information, an operation button operated to display a continuation of the information, and a knob An end button for instructing termination of the operation of the de-N, and the information display column other various information are displayed, the search screen including a displayed on the display unit 16 (step S60).

  When the search screen is displayed, first, characters can be input in the title input field (step S61), and then any key operation or button operation in the input unit 21 is waited (step S62). When an up / down key (not shown) in the input unit 21 is operated (step S63; YES), the column in the search screen that enables character input is moved to another input column such as the name input column, for example. (Step S66), the process returns to step S62 and waits for the next input operation.

  If the input operation does not use the up / down keys (step S63; NO), it is next checked whether left / right keys, character keys, delete keys, etc. (not shown) in the input unit 21 have been operated. (Step S64). When any character or the like is input (step S64; YES), the search keyword editing process using the input character or the like in the input field where the character can be input at that time is executed. (To be more specific, a search keyword decision process or the like) is executed (step S67), and the process returns to step S62 again to wait for the next input operation.

  On the other hand, if it is determined in step S64 that the character key or the like has not been operated (step S64; NO), it is confirmed whether or not the search execution button has been operated (step S65). When the search execution button is not operated (step S65; NO), finally, it is confirmed whether or not the end button is operated (step S68), and when the end button is not operated. (Step S68; NO), the process returns to Step S62 and waits for further input operation.

  On the other hand, when the end button is operated in the determination in step S68 (step S68; YES), the value of the terminal end instruction flag is set to “1” in the control unit 11 (step S69), and the above step S62. Return to and wait for further input operations.

  On the other hand, when the search execution button is operated in the determination of step S65 (step S65; YES), it is determined that the catalog search is performed with the search keyword input in each input field at this time. Become. Using this, a content having a title or the like that matches the determined search keyword is extracted from the catalog for content search currently stored in the storage unit 12 (step S70). The contents are displayed as a list (step S71). At this time, the list is displayed on the display unit 16 as a search result list on a screen different from the content reproduction display screen.

  After the search result list is displayed on the display unit 16 by the process of step S71, it waits for the operation of any button or key (step S72) and confirms whether the return button has been operated (step S72). Step S74). When the return button is operated (step S74; YES), the process returns to step S60 and the process is repeated from a new display of the search screen (steps S60 to S71).

  On the other hand, if it is determined in step S74 that the return button is not operated (step S74; NO), it is finally checked whether or not the viewing button is operated (step S75). If the viewing button is not operated (step S75; NO), the process returns to step S72 to wait for the next input operation. When the viewing button is operated (step S75; YES), the viewing button is selected. The content ID of the existing content is stored in the control unit 11 and the reproduction instruction flag in the control unit 11 is set to “1” (step S76), and the process returns to step S62 again to wait for the next input operation.

(B) Operation as Root Node Next, the operation as the root node RN (see FIG. 4) according to the embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing the operation as the root node RN in the main distribution system SM according to the embodiment, and is executed by the control unit 11 in the node N functioning as the root node RN. Further, the processing as the root node RN shown in FIG. 8 is completely independent of the normal message processing as the node N (see step S14 in FIG. 6) described with reference to FIGS. This process is periodically started every time (that is, interrupt process by timer activation, for example), and returns to the original normal process when the process shown in FIG. 8 ends.

  As shown in FIG. 8, in the operation as the root node RN according to the embodiment, first, the concentration level of the distribution request in the content holder CH in which the root node RN stores the content storing the index information EX. (In other words, the index memory CM in the root node RN may be in an unbalanced state like the index memory CM1 illustrated in FIG. 4) (steps S20 and S21).

  Specifically, as the operation of this step S20, for example, the number of index information EX corresponding to a specific content (that is, the number of index information EX in the storage unit 12 in the root node RN) (ie, the number of index information EX corresponding to the specific content) Whether the number of replicas of the specific content occupies most of the storage area, the degree of increase in the number of distribution requests for the content holder CH storing content data corresponding to the specific content, or The number of distribution requests per unit time for the content holder CH is determined by comparison with a preset threshold value.

  When it is determined that the concentration level of the distribution request is high (step S21; YES), it is confirmed whether the assistance request message RMG has been transmitted to the auxiliary server SPM (step S22). If not (step S22; NO), an assistance request message RMG for requesting the helper node SN to participate in the main distribution system SM is immediately sent to the auxiliary server SPM (step S23), and the above-described normal processing as the node N is performed. Return to FIG. 6 and FIG.

  Note that the information for connecting to the auxiliary server SPM (more specifically, for example, the IP address or port number indicating the auxiliary server) is stored in the storage unit 12 at the time of factory shipment of the node N according to the embodiment, for example. Or a ROM (Read Only Memory) (not shown) in the control unit 11.

  The specific contents of the assistance request message RMG are at least the IP address of the root node RN that transmits the assistance request message RMG, the node ID corresponding to the root node RN, and the target of the assistance request message RMG. A content ID corresponding to the content (popular content) is included. In addition, the assistance request message RMG may include an index or the like indicating the degree of urgency for obtaining the helper node SN.

  On the other hand, if it is determined in step S22 that the assistance request message RMG has already been transmitted (step S22; YES), the process returns to the normal processing (see FIGS. 6 and 7) as the node N.

  On the other hand, if it is not determined in step S21 that the concentration of the distribution request with respect to the target content is high (step S21; NO), has the aid request message RMG been transmitted to the auxiliary server SPM? If it has not been transmitted (step S25; NO), since the concentration of distribution requests is low, there is no need to transmit the assistance request message RMG in the first place. Returning to the normal processing described above as N (see FIGS. 6 and 7).

  Further, in the determination in step S25, when the assistance request message RMG has already been transmitted (step S25; YES), it is not determined that the degree of distribution request concentration on the target content is high (step S21; NO). Therefore, the helper node SN does not need to participate in the main distribution system SM. Therefore, the helper node SN is removed from the main distribution system SM in the case where an opportunity to participate again occurs. In order to return it to the original auxiliary system SP, an assistance cancellation message is transmitted from the root node RN to the auxiliary server SPM (step S28), and the above-described normal processing as the node N (see FIGS. 6 and 7). Return to.

  Although not illustrated in FIG. 8, the node N as the root node RN is configured such that the helper node SN participates in or leaves the main distribution system SM in response to the generation of the assistance request message RMG and the assistance cancellation message. There is no need to fulfill the function as the root node RN of the currently popular (popular) content, or the function is started again. More specifically, for example, the routing information stored in the node N as the root node SN is updated in response to the exchange of the message MG such as the assistance request message RMG and the assistance release message, so that the root node It fulfills its function as an RN or does not fulfill its function.

(C) Operation as Auxiliary Server Next, the operation as the auxiliary server SPM (see FIG. 4) according to the embodiment will be described with reference to FIG. FIG. 9 is a flowchart showing the operation as the auxiliary server SPM in the auxiliary system SP according to the embodiment, and is executed by the control unit 11 in the node N functioning as the auxiliary server SPM. Further, the process as the auxiliary server SPM shown in FIG. 9 is an infinite loop pattern process that is repeatedly executed after the power is turned on until the power is turned off.

  As shown in FIG. 9, in the operation as the auxiliary server SPM according to the embodiment, first, the reception of a message from any node N in the main distribution system SM is waited (step S30).

  When any message is received, it is confirmed whether the received message is a valid message for the auxiliary server SPM, that is, whether it is either the assistance request message RMG or the assistance cancellation message (step). S32).

  When the received message is neither the assistance request message RMG nor the assistance cancellation message (step S32; NO), the received message is ignored, and the process returns to step S30 to continue the standby state.

  On the other hand, when the received message is either the assistance request message RMG or the assistance release message in the determination in step S32 (step S32; YES), the received message is the assistance request message RMG. Whether or not (step S33).

  If it is determined in step S33 that the received message is not the assistance request message RMG (step S33; NO), the received message is an assistance cancellation message, so that the helper nodes currently participating in the main distribution system SM The helper node SN that has joined the main distribution system SM in response to the assistance request message RMG from the root node RN that has transmitted the assistance cancellation message among the SNs, withdraws from the main distribution system SM and assists. A withdrawal instruction message for returning to the system SP is transmitted (step S34), and the management list stored in the auxiliary server SPM is updated in order to manage the helper node SN after confirming the withdrawal (step S35), Thereafter, the above-described operation is repeated.

  Here, the management list includes a helper that has joined the main distribution system SM in response to the assistance request message RMG in order to identify a helper node SN to be withdrawn from the main distribution system SM in response to the assistance cancellation message. A list in which the IP address of the node SN is associated with the IP address of the root node RN that has transmitted the assistance request message RMG (that is, the node N that has transmitted the assistance cancellation message) (in other words, which A correspondence table indicating which helper nodes SN have joined the main distribution system SM in response to the assistance request message RMG from the root node RN) is stored in the storage unit 12 in the auxiliary server SPM as the management list. .

  On the other hand, if it is determined in step S33 that the received message is the assistance request message RMG (step S33; YES), then is there actually a helper node SN that can participate in the main distribution system SM? It is confirmed whether there is a free helper node SN that is not used for other purposes (step S36).

  If there is no helper node SN in the free state (step S36; NO), it waits for a predetermined time to wait until any one of the helper nodes SN under management becomes free (step S37). ), Returning to step S36 again, it is repeated to determine whether or not there is an empty helper node SN.

  On the other hand, when it is determined in step S36 that there is an empty helper node SN (step S36; YES), the value of the node ID of the root node RN that has transmitted the assistance request message RMG is the assistance request. It is confirmed whether or not it is equal to the value of the content ID indicating the content managed by the root node RN that has transmitted the message RMG (step S38).

  Here, since the bit length of the node ID is generally as long as 128 bits to 160 bits, the probability that the node ID of the root node RN and the content ID exactly match is very low. For this reason, it is almost certainly possible to make the node ID of the helper node SN completely match the content ID and participate as the root node RN. However, on the other hand, since the probability of matching is not “0” at all, it is necessary to make a determination related to the processing in step S38.

  If the value of the node ID of the root node RN is not equal to the value of the content ID (step S38; NO), the help request message RMG is sent to any helper node SN in the empty state at that time. A node ID having the same value as the value of the content ID indicating the target content (concentration of distribution requests) is allocated, and the root node RN that has transmitted the assistance request message RMG is further contacted. A participation instruction message CMG instructing participation in the main distribution system SM as a node is transmitted (step S44), and the process proceeds to step S35.

  Here, if the value of the node ID of the root node RN is equal to the value of the content ID in the determination in step S38, the help request message RMG is given to one of the helper nodes SN in the empty state at that time. When a node ID having the same value as the value of the content ID indicating the content that is the target of the distribution (concentration of distribution requests) is allocated and then joined to the main distribution system SM, Two nodes having the same node ID coexist.

  Therefore, in order to avoid this situation, when the value of the node ID of the root node RN is equal to the value of the content ID (step S38; YES), a value obtained by adding “1” to the current value of the content ID is set. A new node ID is generated (step S39), and it is confirmed whether another node already having a node ID equal to the newly generated node ID already exists in the main distribution system SM. (Steps S40 and S41). More specifically, for example, a root node confirmation message (a message of a type transferred based on the DHT) is transmitted to the main distribution system SM with the newly generated node ID as a destination, and the current route is Receive a reply of the node ID of the node N functioning as the node RN (in other words, send a message inquiring which node N is the node N that manages the content corresponding to the content ID, and Get a reply).

  When another node that already has a node ID equal to the newly generated node ID already exists in the main distribution system SM (step S41; YES), the newly generated node ID Further, “1” is added to the value to generate a new node ID again (step S43), and the process returns to step S40 to make the same determination again.

  On the other hand, if it is determined in step S41 that there is no other node in the main distribution system SM that already has a node ID equal to the newly generated node ID (step S41; NO), the available space The node ID of the value at that time is assigned to one of the helper nodes SN in the state, and further, the root node RN that has transmitted the assistance request message RMG is used as the contact node to participate in the main distribution system SM. A participation instruction message CMG is sent to the empty helper node SN (step S42), and the process proceeds to step S35.

  As described above, when there is already a node N having a node ID that completely matches the value of the content ID, the node ID of the helper node SN is set to a value slightly shifted from the content ID, and the main distribution system is used. By joining the SM, it is not possible to become a new root node RN, but it is possible to work as a node having a node ID that is as close as possible to the root node RN (quasi-root node). In this case, although the effect of burdening the storage of the index information of the popular content is slightly reduced, in general, since it can function as the cache node CN, a certain effect can be obtained.

(D) Operation as Helper Node Finally, the operation as the helper node SN (see FIG. 4) according to the embodiment will be described with reference to FIG. FIG. 10 is a flowchart showing the operation as the helper node SN in the auxiliary system SP according to the embodiment, and is executed by the control unit 11 in the node N functioning as the auxiliary server SPM.

  As shown in the left of FIG. 10, in the operation as the helper node SN according to the embodiment, first, the activation process as the helper node SN is performed, and the standby state of the participation instruction message CMG from the auxiliary server SPM is entered (step S50, S50A; NO).

  When the participation instruction message CMG is received (step S50A; YES), the helper node SN participates in the main distribution system SM, and a thread for performing message processing as DHT is started (step S51). After participating in the main distribution system SM, as described above, as a node (quasi-root node) having a node ID as close as possible to the root node RN of the content that is the target of the participation instruction message CMG or the root node RN. Function.

  Next, during the operation as the helper node SN, the processes of steps S52 to S56 described below are periodically repeated. That is, while waiting for a preset fixed period of time to wait for the natural state of the concentration state in response to the distribution request for the content (step S52), the concentration state is confirmed (steps S53 and S54).

  Here, specifically, as the operation of steps S53 and S54, as in the case of step S20 in FIG. 8, for example, compared with the information amount of the storage area of the index information EX in the storage unit 12 in the helper node SN. Thus, the number of index information EX corresponding to the specific content (that is, the number of replicas of the specific content) occupies most of the storage area, and the content data corresponding to the specific content is stored. The degree of increase in the number of distribution requests for the content holder CH, or the number of distribution requests per unit time for the content holder CH may be determined by comparing with a preset threshold. The determination process in steps S53 and S54 is different from that in step S20 above in the distribution request. Since determining whether the medium state is eliminated is the object, determination may be performed in the case of step S54 with the threshold value and different threshold used in the determination of step S20.

  Next, in the confirmation processing in steps S53 and S54, when it is not determined that the concentration level of the distribution request is in a concentrated state (step S54; NO), the processing using the general DHT started as step S51 is ended. (Step S56), the process returns to the process of Step S50 and enters the standby state for the participation instruction message CMG.

  On the other hand, in the confirmation processing in steps S53 and S54, when distribution requests for the content are still concentrated (step S54; YES), it is confirmed whether or not the withdrawal instruction message from the auxiliary server SPM has been received ( Step S55). If the withdrawal instruction message has not been received (step S55; NO), the process proceeds to step S52, and continues to function as the root node RN or quasi-root node corresponding to the content, while step S52 is performed. The process of thru | or S55 is repeated.

  On the other hand, if it is determined in step S55 that a withdrawal instruction message has been received (step S55; YES), the DHT message processing thread started as step S51 is terminated (step S56), and the process returns to step S50 and participates. The standby state of the instruction message CMG is entered.

  Next, the DHT message processing thread started as step S51 will be specifically described with reference to the flowchart shown on the right side of FIG. Note that this flowchart corresponds to the flowchart shown in FIG. 6 excluding processing such as content request / reproduction.

  As shown on the right of FIG. 10, in the DHT message processing thread, the participation request message is sent to the helper node to participate in the main distribution system SM in response to the participation instruction message CMG received in the process of step S50. The SN transmits to the contact node that acts as an intermediary when participating in the main distribution system SM (step S57), and then enters a standby state for a message including a reply message to the participation request message (step S58; NO). As the step S57 is executed, the contact node may attach all the index information EX stored at that time to the reply message. When the helper node SN builds its own index information EX based on this information, the helper node SN can immediately function as the root node RN.

  When any message is received while waiting for reception (step S58; YES), various message processing corresponding to the type of the received message is performed (step S59 (see step S14 in FIG. 6)). Thereafter, the process returns to step S58 to enter a message reception standby state.

  As described above, according to the operation of the distribution system S according to the embodiment, the assistance request message RMG is output to the auxiliary server SPM when the distribution request for the specific popular content exceeds the threshold, and the assistance request message RMG is output. Since the helper node SN is made to participate in the main distribution system SM corresponding to the above, the number of index information EX corresponding to the popular content increases in the nodes belonging to the main distribution system SM due to the concentration of distribution requests for the popular content. Thus, it is possible to prevent a reduction in the number of stored other index information EX corresponding to other contents caused by.

  Therefore, it is possible to prevent other contents corresponding to the other index information EX from becoming undeliverable by reducing the number of stored other index information EX, and to improve convenience and distribution efficiency in the main distribution system SM. It can contribute to improvement.

  Further, since it is determined whether or not the distribution request for the popular content exceeds the threshold based on at least one of the number of distribution requests per unit time and the number of replicas, the actual number of distribution requests or the number of replicas By determining based on the above, it is possible to efficiently perform cooperation between the main distribution system SM and the auxiliary system SP.

  Furthermore, when the distribution request for the popular content falls below a predetermined threshold, the helper node SN participating in the main distribution system SM is removed from the main distribution system SM, so the distribution situation of the popular content is improved. In some cases, the helper node SN can be removed from the main distribution system SM to return to the state of the original main distribution system SM, and the auxiliary system SP can be put on standby in preparation for the subsequent deterioration of the distribution situation. .

  In addition, the value of the node ID of the helper node SN is set to a value corresponding to the value of the content ID corresponding to the popular content, and participates in the main distribution system SM, and distribution of the popular content in the main distribution system SM is performed. Since it is used for control, the helper node SN that participates can be surely used for distribution control of popular content.

  Further, when the value of the node ID of the root node RN is a value corresponding to the value of the content ID corresponding to the popular content, the value of the node ID for identifying the helper node SN is set to the content ID corresponding to the popular content. Since it is set to a value related to the value and participates in the main distribution system SM, the helper node SN can participate in the main distribution system SM without affecting the distribution of contents in the main distribution system SM.

  In addition, since the value related to the value of the content ID corresponding to the popular content is a value that is most recently larger than the value of the content ID corresponding to the popular content, the helper node SN can be more quickly and smoothly connected to the main distribution system SM. Can participate.

  Furthermore, when the helper node SN participating in the main distribution system SM is removed from the main distribution system SM, a withdrawal instruction message for leaving the main distribution system SM is transmitted to the helper node SN. The helper node SN participating in the main distribution system SM can be quickly returned to the management of the auxiliary server SPM.

  Furthermore, since the storable number of index information EX in the helper node SN is at least twice the storable number of index information EX in the nodes in the main distribution system SM, the distribution status of popular content in the main distribution system SM A helper node SN having sufficient functions for improvement can participate in the main distribution system SM.

  Further, when participating in the main distribution system SM, the routing information is acquired from the route node RN in the main distribution system SM, and the acquired routing information is stored in the helper node SN to be used for distribution of popular contents. The helper node SN can participate in the main distribution system SM by simple and quick processing, and can be immediately used for distribution of popular contents.

  In the embodiment described above, the node ID when the helper node SN is allowed to participate in the main distribution system SM is set while being increased by “1” in relation to the existing content ID or node ID (see FIG. In addition to this, 9 steps S39 and S43) may be set to decrease by “1”. Also with this configuration, the same effects as those of the above embodiment can be obtained.

  In the above-described embodiment, the case where the cache node CN does not exist in the main distribution system SM has been described. However, the part according to the present invention of the functions of the root node RN in the embodiment applies to the cache node CN as it is. It is also possible.

  Further, the programs corresponding to the flowcharts shown in FIGS. 8 to 10 described above are recorded in an information recording medium such as a flexible disk or a hard disk, or acquired and recorded via the Internet, etc. The computer can be made to function as the control unit 11 in the root node RN, the auxiliary server SPM, and the helper node SN according to the embodiment.

  As described above, the present invention can be used in the field of content distribution via a network, and particularly when applied to the field of content distribution in a download format, a particularly remarkable effect can be obtained.

It is a schematic diagram (I) which shows the outline | summary of the delivery system which concerns on embodiment, (a) is a schematic diagram which shows ID space in the said delivery system, (b) is a figure which illustrates index information. It is a schematic diagram (II) which shows the outline | summary of the delivery system which concerns on embodiment, (a) is a schematic diagram which shows the transmission state of the message in the said delivery system, (b) is transmission of the said message represented as a spanning tree. It is a figure which shows a state. It is a schematic diagram (III) which shows the outline | summary of the delivery system which concerns on embodiment. It is a figure explaining the principle of this invention. It is a block diagram which shows the outline structure of the node which concerns on embodiment common about a content holder etc. It is a flowchart which shows the whole common operation | movement in the node which concerns on embodiment. It is a flowchart which shows the detail of the common operation | movement in the node which concerns on embodiment. It is a flowchart which shows the operation | movement in the root node which concerns on embodiment. It is a flowchart which shows the operation | movement in the auxiliary server which concerns on embodiment. It is a flowchart which shows the operation | movement in the helper node which concerns on embodiment.

Explanation of symbols

11 Control unit 12 Storage unit 13 Buffer memory 14 Decoder unit 15 Video processing unit 16 Display unit 17 Audio processing unit 18 Speaker 20 Communication unit 21 Input unit 22 Bus Rc, RN Ring EX Index information CH Content holder RQ, RQ1, RQ2, RQ3 Requester RN Root node CN Cache node PUBmsg Public message QRmsg Distributor inquiry message N Node RT Reply information SM Main distribution system CM1, CM2 Index memory SP Auxiliary system S Distribution system SPM Auxiliary server SN Helper node RMG Assistance request message CMG Join instruction message

Claims (14)

A main distribution system configured to connect a plurality of node devices via a network and distribute distribution information stored in any of the node devices to any of the other node devices;
Auxiliary for storing distribution information location information including distribution information identification information for identifying the distribution information, and storage device identification information for identifying a storage device that is the node device storing the distribution information An auxiliary system that includes an auxiliary device that includes a storage unit, and a management device that includes a management unit that manages the auxiliary device;
A distribution system including:
The main distribution system includes a node device that manages the location of the distribution information, the node device including a location information storage unit that stores the distribution information location information,
The location of the distribution information is managed by the node device to which identification information having a value equal to or closest to the value of the distribution information identification information for identifying the distribution information is provided,
The auxiliary storage means is capable of storing a larger number of distribution information location information than the number of distribution information location information that can be stored in the location information storage means,
Furthermore, the main distribution system is based on the number of the distribution information location information corresponding to the specific distribution information that is one of the distribution information among the distribution information location information stored in the location information storage unit . A control device that is the node device comprising auxiliary request information output means for outputting auxiliary request information for requesting auxiliary participation of the auxiliary device into the main distribution system to the management means;
The management means that acquired the assistance request information
When the value of the control device identification information for identifying the control device is equal to the value of the distribution information identification information for identifying the specific distribution information, Generating means for generating identification information having a small value most recently;
Confirmation means for confirming whether or not the node device to which identification information equal to the identification information generated by the generation means is already present in the main distribution system;
When the node device to which the identification information equal to the identification information is not already present in the main distribution system, the identification information is allocated to the auxiliary device, and the auxiliary device is transferred to the auxiliary distribution system. Instructing the auxiliary device to manage the location of the specific distribution information in the main distribution system;
Distribution system, characterized in that it comprises a. A control device included in the main distribution system according to claim 1,
A control apparatus comprising the request information output means. The control device according to claim 2,
The control device, wherein the auxiliary request information output means outputs the auxiliary request information to the management means when the number of pieces of distribution information location information is greater than or equal to a preset threshold value. The control device according to claim 2 or 3,
In the case where the auxiliary device participates in the main distribution system, when the number of the distribution information location information corresponding to the specific distribution information becomes less than a predetermined threshold, the participating auxiliary device is A control apparatus, further comprising: a withdrawal request information output unit that outputs, to the management unit, withdrawal request information for requesting separation from the main distribution system. A management device included in the auxiliary system according to claim 1,
A management apparatus comprising the management means. The management device according to claim 5,
The management means includes
When the value of the control device identification information for identifying the control device is equal to the value of the distribution information identification information for identifying the specific distribution information, Generating means for generating identification information having a small value most recently;
Confirmation means for confirming whether or not the node device to which identification information equal to the identification information generated by the generation means is already present in the main distribution system;
When the node device to which the identification information equal to the identification information is not already present in the main distribution system, the identification information is allocated to the auxiliary device, and the auxiliary device is transferred to the auxiliary distribution system. Instructing the auxiliary device to manage the location of the specific distribution information in the main distribution system;
A management apparatus comprising: The management device according to claim 6,
The management means, when the auxiliary device is participating in the main distribution system, when acquiring the withdrawal request information for requesting that the participating auxiliary device is detached from the main distribution system, A management apparatus , further comprising: a leaving instruction information transmitting unit that transmits leaving instruction information indicating that the auxiliary apparatus is leaving the main distribution system . An auxiliary device included in the auxiliary system according to claim 1,
An auxiliary device comprising the auxiliary storage means . The auxiliary device according to claim 8,
The auxiliary device characterized in that the number of storable distribution information location information in the auxiliary storage means is at least twice the storable number of the distribution information location information in the location information storage means . The auxiliary device according to claim 8 or 9,
When participating in the main distribution system, distribution control information that is necessary for distributing the specific distribution information and includes the distribution information location information is sent to any one of the node devices in the main distribution system. Acquisition means for acquiring from,
Storage control means for storing the acquired distribution control information in the auxiliary storage means for use in distributing the specific distribution information;
Assist device, characterized in that it comprises a. A program for a control device that causes a computer included in any one of the node devices in the main distribution system according to claim 1 to function as the control device according to any one of claims 2 to 4. . A program for a management apparatus that causes a computer included in the management apparatus in the auxiliary system according to claim 1 to function as the management unit according to any one of claims 5 to 7 . A program for an auxiliary device, which causes a computer included in the auxiliary device in the auxiliary system according to claim 1 to function as the auxiliary device according to any one of claims 8 to 10 . A main distribution system configured to connect a plurality of node devices via a network and distribute distribution information stored in any of the node devices to any of the other node devices;
Auxiliary for storing distribution information location information including distribution information identification information for identifying the distribution information, and storage device identification information for identifying a storage device that is the node device storing the distribution information An auxiliary system that includes an auxiliary device that includes a storage unit, and a management device that includes a management unit that manages the auxiliary device;
A distribution system including:
The main distribution system includes a node device that manages the location of the distribution information, the node device including a location information storage unit that stores the distribution information location information,
The location of the distribution information is managed by the node device to which identification information having a value equal to or closest to the value of the distribution information identification information for identifying the distribution information is provided,
The auxiliary storage means is a distribution system control method executed in the distribution system in which a larger number of distribution information location information can be stored than the number of distribution information location information that can be stored in the location information storage means. And
Based on the number of pieces of distribution information location information corresponding to specific distribution information that is one piece of the distribution information among the distribution information location information stored in the location information storage means, the control device that is the node device. An auxiliary request information output step for outputting auxiliary request information for requesting auxiliary participation in the main distribution system of the auxiliary device to the management means;
When the value of the control device identification information for identifying the control device is equal to the value of the distribution information identification information for identifying the specific distribution information, the distribution information is acquired by the management means that has acquired the auxiliary request information. An identification information having a value that is most recently large or a value that is most recently small with respect to the value of the identification information is generated, and the node device to which identification information equal to the generated identification information is assigned is already in the main distribution system. If the node device does not already exist in the main distribution system, the identification information is allocated to the auxiliary device, and the auxiliary device is transferred to the main distribution system. Instructing participation and causing the auxiliary device to manage the location of the specific distribution information in the main distribution system;
A distribution system control method comprising:

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