JP2006244223A - P2p content transfer method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To positively and inexpensively acquire presence of terminals composing a P2P network and a terminal group to which the terminals belong to even in an environment not needing a particular server, and to acquire contents addressed to one's terminal after rejoining even when a content receiving terminal leaves the P2P network. <P>SOLUTION: A step is provided for storing information of the terminal group 32 in a distribution hash table 31 composed of terminals having high terminal function capacity. A step is provided for sharing presence information belonging to the content receiving terminal 152 in the terminal group 32. A step is provided for dividing contents and setting them adrift in the terminal group 32 when the transfer target content receiving terminal 152 is not in the P2P network. A step is provided for requesting contents addressed to one's terminal to the terminal group 32 and acquiring them when the content receiving terminal 152 rejoins the P2P network. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for transferring content in a peer-to-peer (P2P) network, and in particular, even when a terminal to which content is transferred does not participate in the network, The present invention relates to a P2P content transfer method that enables a terminal to acquire content when the terminal joins a network.

  When a central server is provided in the network and contents are transferred through the central server, a high-speed and large-capacity central server is required, and traffic is concentrated around the server. In P2P networks, many of the disadvantages of using a central server have been solved by transferring content directly between terminals (end-to-end). The P2P network is maintained by each terminal autonomously joining / leaving the P2P network.

  However, in the conventional content transfer in the P2P network, for example, when a user A tries to transfer content to a certain user B, the content cannot be directly transferred if the terminal of the user B is disconnected from the network. Become. For example, many IP (Internet Protocol) messenger software has an end-to-end content transfer function, but content cannot be transferred when the transfer target terminal is disconnected from the network. . In order to solve this problem, (1) a server for temporarily storing content is prepared in the network, or (2) the content is temporarily stored in a terminal currently participating in the network using a P2P network. Techniques such as storage and drifting are taken. Here, drifting is used as a concept in which content flows between terminals.

  The method of preparing the server is considered to ensure that the transferred content reaches the content receiver by using a reliable server, but the data size of rich content etc. is increasing year by year. The problem of the increase in storage (storage device) cost and the increase in network traffic cost to cope with the ever-increasing data size.

  On the other hand, in the method of temporarily storing and drifting content, the content transfer is enabled by drifting the transfer content in the P2P network and the content receiver acquires the drifting content. As a method for the content receiver to acquire the drifting content addressed to the own node from the P2P network, there is a method of broadcasting the P2P network as used in Gnutella (Gnutella). Due to the increase in the number of terminals to be configured, the search cost for the search packet to reach the terminal holding the target content becomes high.

  In order to solve this problem, various content search methods have been proposed for content receivers to search for content.

  In Japanese Patent Application Laid-Open No. 2003-178089 (Patent Document 1), a control server in a P2P network sets an interest vector based on a user's interest information and a parameter indicating the interest and interest of each genre. An interest vector close to the interest vector is selected and set as an inquiry destination for content presence / absence. With this configuration, it is possible to perform highly accurate content search processing without having to store content information in the control server. However, a content search method that uses an interest vector such as a certain genre or artist has a broad concept of a content acquirer such that a large number of users are assumed as acquisition users of a certain content. Not suitable for searching content addressed to. That is, the concept of the interest vector does not exhibit effectiveness under a situation where the content and the user are linked one-on-one, such as content addressed to a specific individual.

  On the other hand, as a method of drifting content to the P2P network, conventionally, by distributing and managing copies evenly so that content does not concentrate on a specific terminal, for example, content is lost when a specific terminal goes down. And ensure that no content is lost from the P2P network. In Japanese Patent Laid-Open No. 2004-220183 (Patent Document 2), the storage capacity of each terminal of a group is determined by grouping terminals constituting a distributed storage process and by controlling a group management apparatus installed for the group. It has been proposed to implement a data storage process that does not fail according to the conditions.

  However, although the concept of terminal grouping is useful for the increase in the number of terminals constituting a network, each terminal that constitutes a group in the P2P network environment participates in and leaves the network, so the terminals that have left In order to rejoin the same group, an inquiry to a specific server is required. In addition, if the disconnected terminal cannot rejoin the same group, the content cannot be distributed and managed equally within the group, and the content receiving terminal belonging to the specific group has left the network. Even if the content sending terminal saves a copy of the content on another terminal in the group to which the receiving terminal belongs so that the content can be received even if the content receiving terminal cannot rejoin the same group, the copy of the content makes sense In addition, there is a problem that the content sender cannot determine the copy destination terminal group unless the content receiver can know which terminal group the content receiver belongs to.

Also, if the group to which each terminal belongs and presence information (participation / extraction from the network, etc.) can be acquired, the content is transferred to the receiving terminal end-to-end if the content receiving terminal is participating in the P2P network. However, it is possible to use different methods, such as drifting content to other terminals if the user is leaving. The use of a distributed hash table (DHT) is conceivable as a method for managing group membership and presence information without using a server. Regardless of what you think is not likely to change the information after that once it is decided like belonging group, updating information in the distributed hash table that needs frequent updating like presence information, This causes a problem that the work cost increases. Also, the presence information is not updated from the terminal side to the distributed hash table, but the information is not updated. This is actually the case when the terminal makes an abnormal detachment from the P2P network. This results in a mismatch state that the terminal is participating in the distributed hash table even though the terminal does not already exist in the P2P network.
JP 2003-178089 A JP 2004-220183 A

  As described above, in the conventional method, without using a specific server, the presence (participation / leaving information, etc.) of the terminals constituting the P2P network and the terminal group to which the terminals belong are reliably and inexpensively acquired. Is difficult.

  An object of the present invention is to make it possible to acquire the presence (participation / leaving information, etc.) of a terminal constituting a P2P network and a terminal group to which the terminal belongs reliably and at low cost in an environment that does not require a specific server. An object of the present invention is to provide a content transfer method that can reliably acquire content addressed to itself when the content receiver rejoins the P2P network even when the content receiver is leaving the P2P network.

  The P2P content transfer method of the present invention is a method for transferring content between terminals on a P2P network in which a plurality of terminals transmit / receive arbitrary information and / or content data by autonomous distributed cooperation, A terminal group is configured by a group of terminals having relevance, the terminal group information is stored in a distributed hash table including terminals selected according to the terminal function capability from the P2P network; The stage of sharing the presence information that the content receiving terminal belongs to within the terminal group to which the content receiving terminal belongs, and the terminal that has grasped the content transmitting terminal by referring to the distributed hash table to which terminal group the content receiving terminal belongs Presence information of content receiving terminal for group When the content receiving terminal to be transferred and the content receiving terminal to be transferred are separated from the P2P network, the content is divided in consideration of the data size of the content to be transferred and the terminal capability of the terminal group, and the P2P in the terminal group A stage where distributed copies of content are distributed to terminals currently participating in the network, and when the content receiving terminal to be transferred joins the P2P network, the content receiving terminal to which the transfer is assigned belongs first. Rejoining the terminal group, requesting the terminal group for content addressed to the terminal group, and if content information addressed to the terminal itself exists, acquiring the content and notifying the terminal group that the content has been acquired; Have.

  That is, in the present invention, even when a terminal that is a target of content transfer in the P2P network does not participate in the network, the content is temporarily stored in the terminal that is connected to the network, and when the transfer target terminal rejoins the network, it is addressed to itself. To discover and retrieve the content. This makes it possible to deploy and acquire temporarily stored content in the network efficiently without requiring a specific server.

  In the present invention, each terminal participating in the P2P network periodically acquires the performance value of the own terminal, and a terminal having a capability equal to or higher than a predetermined threshold notifies the distributed hash table of the capability of the own terminal. In the case where the terminal has a better capability than the terminal that already configures the distributed hash table, a step of registering the terminal as a terminal configuring the new distributed hash table may be further provided.

  In the present invention, each terminal belonging to the terminal group exchanges the performance value acquired together with the stage of periodically acquiring the performance value of the own terminal with another terminal in the terminal group, and the most performance value in the terminal group. Registering the determined address of the GW-RP terminal as the address of the GW-RP terminal of the own terminal group stored in the distributed hash table; When a new GW-RP terminal is selected from within the terminal group and the new GW-RP terminal is registered in the distributed hash table, and the GW-RP terminal A request related to the content receiving terminal of the terminal group to which the GW-RP terminal belongs is received, and the terminal group to which the GW-RP terminal belongs Performing flooding and returning the acquisition information to the content transmission terminal, and each terminal of the terminal group stores the cache information of the GW-RP terminal and other terminals of the terminal group, and at the time of rejoining the P2P network And rejoining the same terminal group using the cache information. When setting the GW-RP terminal, when the content transmitting terminal searches the distributed hash table by the identifier of the content receiving terminal, the address of the GW-RP terminal of the terminal group to which the content receiving terminal belongs is sent to the content transmitting terminal. It may be returned.

  The terminals that make up the terminal group may periodically detect whether the terminals that construct the link mutually participate in the network, and update the presence information due to abnormal detachment of the terminals.

  In the present invention, information having a relatively low change frequency is stored in the distributed hash table, and information having a relatively high change frequency is managed by holding a copy of the information in the terminal group, and the distributed hash table It is preferable to reduce the information update cost.

  The present invention can (1) obtain the presence information (participation / departure) of a terminal connected to the P2P network with high reliability without using a full network search in an environment in which no server is provided. It is possible to find and acquire the content addressed to the terminal transmitted while leaving the network at a reduced search cost. (3) It is possible to delete unnecessary drifting content and configure a P2P network. Therefore, there is an effect that it is possible to drift content within the P2P network without depending on the data size.

  Next, a preferred embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a network to which a content transfer method according to an embodiment of the present invention is applied, and a terminal connected to the network.

  User A's terminal 1 (user terminal # 1) and user B's terminal 2 (user terminal # 2) are connected to a transmission network 3 such as the Internet. The P2P network is logically configured on a transmission network 3 as a physical network. The terminals 1 and 2 include a central processing unit (CPU), secondary storage devices 14 and 24, and a network interface as physical devices, and these performance values differ depending on the terminal type. Terminals 1 and 2 logically include applications 11 and 21, file transfer apparatuses 12 and 22 that transfer files via the P2P network, and a P2P communication apparatus 13 that configures an interface to the P2P network and communicates with the P2P network. 23.

  Since the applications 11 and 21 are the same in both the terminals 1 and 2, the application 11 of the terminal 1 will be described below. This application is generally software and is executed by a CPU provided in the terminal. However, this application realizes the function of each functional unit described below. Therefore, each functional unit is implemented by hardware. By configuring, functions equivalent to the applications 11 and 21 can be realized.

  The application 1 can be broadly classified as a functional unit, and measures basic information (terminal identification number (ID) of the terminal and connection state to the network) about the terminal, and a terminal performance information value. A terminal performance information processing unit 112 that manages terminal performance information, a terminal information acquisition processing unit 113 that performs processing for acquiring terminal information by performing processing related to a distributed hash table (DHT), and various processes for content The content processing unit 114 is executed.

  The terminal basic information management unit 111 includes a terminal state transition management unit 1111 that manages terminal state transitions (participation in and withdrawal from the network), and a terminal identification information management unit 1112 that manages information related to terminal IDs. . The terminal performance information processing unit 112 acquires terminal performance information management unit 1121 that acquires terminal performance information that is information related to performance values of physical devices that constitute the terminal, and acquires terminal performance values from the terminal performance information management unit 1121. A performance information determination processing unit 1122 that exchanges these performance values with other terminals to determine the performance of each terminal is provided. The terminal information acquisition processing unit 113 includes a DHT information search processing unit 1131 that performs a search process using a distributed hash table (DHT), and an in-terminal group information management unit 1132 that manages information related to the terminal group. The content processing unit 114 determines the number of content divisions, a content division processing unit 1141 that divides content, a content search processing unit 1142 that searches for content drifting in the network, and drifting content. A content acquisition processing unit 1143 to be acquired and a content deletion processing unit 1144 to perform content deletion processing are provided.

  Next, with regard to the content transfer method according to the present invention, (1) terminal initial setting and performance determination, (2) DHT (distributed hash table) terminal and GW-RP terminal determination, (3) terminal group configuration, The description will be divided into 4) terminal information registration, (5) content transfer, and (6) content acquisition and deletion.

  FIG. 3 shows an overview of the network configuration. As described above, the P2P network is logically configured on the transmission network 3. Further, terminals included in the network are grouped into a terminal group 32. For each terminal group, a GW-RP terminal 153 having a gateway function and a function for managing presence information of terminals in the terminal group is set. Furthermore, a plurality of DHT terminals 154 that configure a distributed hash table (DHT) and store a part of the distributed hash table are set in the network. A distributed hash table 31 is formed by the group of DHT terminals 154. Since it is a P2P network, each terminal in the network can function as the content transmission terminal 151, the content reception terminal 152, the GW-RP terminal 153, and the DHT terminal 154, but the terminal is a GW-RP terminal. In order to function as the H.153 or DHT terminal 154, the terminal needs to satisfy certain terminal performance conditions. Information regarding each terminal includes information managed by the DHT terminal 154 and information managed in the terminal group. Each terminal uses these two types of information properly according to the service request. As an example, static information with a relatively low change frequency (terminal identifier and group identifier to which the terminal belongs) is managed in a distributed hash table, and dynamic information with high change frequency such as terminal presence information is used. Information is managed in the terminal group.

(1) Terminal initial setting and performance determination method:
As described above, the terminal includes a central processing unit, a secondary storage device, and a network interface as physical devices, and performance values differ depending on the terminal type. Therefore, the terminal performance information management unit 1121 periodically acquires information regarding the performance values of these physical devices, and creates terminal performance information indicating the physical performance values of the terminals. The terminal joins / leaves the P2P network, but the terminal performance information management unit 1121 determines how much the terminal has joined the P2P network in a certain period of time. The ratio is used as the terminal's keep alive performance value. Thereafter, the terminal performance information management unit 1121 acquires the terminal performance value from the physical performance value and the lifetime performance value. As shown in FIG. 4, the performance value includes, for example, a CPU specification, a free capacity of a hard disk device (HDD) in a terminal, a bandwidth of a network (NW) to which the terminal is connected, and the like. Based on these performance values, performance values for evaluation with other terminals are determined. In the figure, the performance value for evaluation is represented by a function f for the CPU specifications, HDD free capacity, network bandwidth, and survival time.

  On the other hand, the terminal identification information management unit 1112 of each terminal creates an ID for uniquely identifying the terminal within the P2P network as an initial setting of the terminal. As this ID, for example, the mail address of the user who owns (or uses) the terminal can be used. The terminal identification information management unit 1112 applies a hash function to the mail address to generate a hash key. This hash key is used as an identifier for uniquely identifying the terminal for searching in the DHT information search processing unit 1131 described later.

(2) Determination of DHT terminal and GW-RP terminal:
When the initial setting of each terminal is performed as described above and the performance value of the terminal is acquired, those satisfying a certain terminal performance condition among the plurality of terminals are determined as the DHT terminal 154 and the GW-RP terminal 153. The In particular, a terminal having extremely high terminal function capability in the network is used as the DHT terminal 154 that stores a part of the distributed hash table in order to form the distributed hash table.

  As illustrated in FIG. 4, the performance information determination processing unit 1122 of each terminal acquires the terminal performance value from the terminal performance information management unit 1121. Further, the P2P communication device 13 is used to notify the performance value to the performance information determination processing unit of the terminals belonging to the same terminal group. When the performance information determination processing unit 1122 acquires the performance value of each terminal in this way, the performance information determination processing unit 1122 determines that the performance of its own terminal is higher than the performance value of the other terminal acquired in this way. In the case of higher rank, the terminal is provisionally determined to be the GW-RP terminal 153 in the terminal group to which it belongs. Then, the temporarily determined GW-RP terminal searches the DHT information search processing unit 1131 using its own terminal ID, that is, the hash key described above, and sets its own address to the table of terminal groups to which the own terminal belongs. Registration processing is performed as a new GW-RP terminal.

  Next, as illustrated in FIG. 5, when the performance value of the self terminal exceeds a certain performance threshold, the GW-RP terminal notifies the performance value of the self terminal to the DHT terminal group. When the notified terminal has better performance than that of the currently configured DHT terminal group, the DHT terminal group newly operates the GW-RP terminal as a constituent terminal of the DHT terminal group. . Specifically, the DHT terminal 154 selects a terminal having a particularly high performance value from the GW-RP terminals registered in the distributed hash table 31 in the DHT information search processing unit 1131, and creates a new distributed hash table. And take over the data from the old distributed hash table. Then, in the terminal group to which the GW-RP terminal that has newly behaved as a DHT terminal belongs, the GW-RP terminal 153 is newly treated as a DHT terminal, so that the GW-RP terminal 153 is newly added. elect.

(3) Configuration of terminal group:
In the present embodiment, a terminal group is configured by terminals that are mutually related. Here, the relevance may be, for example, geographically or network topologically close to each other. Alternatively, it may be such that when a search packet such as flooding is transmitted from a certain terminal, responses from all terminals can be expected within a sufficiently allowable time range. In the latter case, the terminal group is configured with terminals so that responses from all terminals can be expected within a time range that is sufficiently allowable when a search packet such as flooding is transmitted.

  When a certain terminal joins the P2P network for the first time, the terminal identification information management unit 1112 of the terminal generates a hash key as described above. Thereafter, the DHT information search processing unit 1131 performs a search using the hash key, determines the terminal group 32 to which the terminal should belong, and simultaneously acquires the address of the GW-RP terminal 153 of the terminal group. . After that, the newly joined terminal uses the terminal group information management unit 1132 to obtain the address of the terminal in the terminal group by flooding starting from the GW-RP terminal 153, and establishes a link with one of the obtained terminal addresses. To do. In this way, the terminal participates in the P2P network.

  The terminals participating in the P2P network periodically acquire the address information of each terminal in the terminal group by the terminal group internal information management unit 1132 and search the distributed hash table 31 at the time of rejoining to determine the terminal group. In order to avoid the need for searching, when rejoining, the address information is used to join the terminal group. In addition, when rejoining the network, the terminal uses an address with a high probability of being able to rejoin the terminal group, for example, a fixed address among the obtained addresses, and also establishes a connection based on the length of the connection time. The order of addresses to be used is provided. If it is not possible to rejoin the terminal group by these procedures, the terminal to rejoin confirms the GW-RP terminals 153 of the terminal group by the above-described distributed hash table search, and performs the above-described procedure in the same manner.

(4) Registration of terminal information:
In this embodiment, static information such as a hash key of a user who owns the terminal and information such as a public key for securely transferring content are stored in the distributed hash table. Then, the DHT information search processing unit 1131 performs a search using its own hash key, or registers information in the distributed hash table (search table). In addition, there are many types of information held by the terminal, but even if it is information other than the user's hash key or public key, if the information has a relatively low update frequency, the information is registered in the distributed hash table. It is also permitted to do.

  By adopting such a procedure, it becomes possible to reduce the update frequency of information in the DHT information search processing unit 1131 of the DHT terminals constituting the distributed hash table 31, minimizing the update load, It becomes possible to respond to backup and read requests.

  Among the information held by terminals, dynamic information such as IP addresses of terminals, presence information (participation / leaving), and performance values obtained by the terminal state transition management unit 1111 of terminals are stored in the terminal group 32. By storing a copy of the information among a plurality of terminals in the terminal state transition management unit 1111 of those terminals, the terminals hold each other. By performing Byzantine agreement 155 between terminals having information copies regularly or at the time of information update, it is possible to prevent inconsistency of information held by the terminals and improve fault tolerance. According to the Byzantine agreement (also known as the Byzantine general issue), even if there are missing or inconsistent information between terminals, or if some terminals fail, It is mathematically proven that you can get the right information. In addition, there are many types of information held by the terminal. However, even if information other than the terminal IP address, presence information (participation / leaving) and performance value is relatively frequently updated, the terminal It is also permitted to manage information between terminals in group 32.

  By adopting such a procedure, it is possible to update information with a relatively high update frequency by an update process between terminals in a specific terminal group 32. As a result, there is no need for information update processing in the entire P2P network, particularly information update processing in the distributed hash table, and localization of the information can improve the accuracy of acquiring necessary terminal information.

(5) Content transfer:
Next, content transfer will be described. When the content sender terminal (content transmission terminal 151) transfers the content to the content receiver terminal (content reception terminal 152), as shown in FIG. 6, for example, the content receiver (transfer destination user) By using a hash function from the mail address, a hash key of the content receiving terminal 152 is generated. Then, using this hash key, the DHT information search processing unit 1131 of the DHT terminal 154 in the DHT terminal group is searched (that is, the distributed hash table 31 is searched), and the content receiving terminal 152 belongs. And the address of the GW-RP terminal 153 of the terminal group 32 is acquired. Thereafter, the content transmission terminal 151 requests the GW-RP terminal 153 for information related to the content recipient's terminal, and the GW-RP terminal 153 performs a broadcast search within its own terminal group to receive the content. Information related to the terminal 152 is acquired, and information is returned to the content transmission terminal 151. Also, a terminal having related information is allowed to return information directly to the content transmission terminal 151.

  Next, the content transmission terminal 151 acquires the presence information of the content reception terminal 152 from the terminal state transition management unit 1111 of a plurality of terminals in the terminal group 32. If the content receiving terminal 152 is participating in the P2P network, the content transmitting terminal 151 transfers the content 4 to the content receiving terminal 152 end-to-end. On the other hand, when the content receiving terminal 152 has left the network, as shown in FIG. 7, the content transmitting terminal 151 sends the content 4 to the GW-RP terminal 153 of the terminal group 32 to which the content receiving terminal 152 belongs. Forward. Then, the content division processing unit 1141 of the GW-RP terminal 153 determines the number of divisions of the content 4 and the number of copies of the content fragment 41 created by dividing the content based on the performance value of each terminal in the terminal group 32. The content fragment 41 is transferred (drifted) 42 between the terminals in the terminal group 32.

(6) Content acquisition and deletion:
When the detached content receiving terminal 152 connects to the network again, the content receiving terminal 152 tries to acquire content destined for the terminal and drifting in the network. At that time, as shown in FIG. 8, when the content receiving terminal 152 rejoins the terminal group 32, the content receiving terminal 152 uses the content search processing unit 1142 of the own terminal to broadcast search the content 4 addressed to the own terminal within the terminal group 32. (Arrow 43). When the content 4 addressed to the own terminal exists, the content acquisition processing unit 1143 acquires the content fragment 41 in parallel from a plurality of terminals holding the drifting content fragment 41 (reference numeral 44), and restores the content 4 To do.

  When the content receiving terminal 152 acquires the content in this way, the content receiving terminal 152 notifies (drifts) the content deletion request 45 to the content deletion processing unit 1144 of each terminal in the terminal group 32. In accordance with the content deletion request 45, the content deletion processing unit 1144 of each terminal deletes the content fragments 41 held by those terminals. The content deletion request 45 drifts in the terminal group 32 over a certain period, so that the deletion request notification 45 can be reached even for a terminal in a detached state.

  By the way, even when the content receiving terminal 152 does not acquire the content, the content fragment 41 exists and drifts in the terminal group 32. In this case, when the content drifting is performed for a certain period of time. The content deletion processing unit 1144 of each terminal deletes the content fragments 41 according to the performance value of the terminal performance information management unit 1121 of its own terminal, and the content fragments 41 that are unlikely to be acquired increase in the terminal group 32. To prevent.

It is a figure which shows the network with which the content transfer method of one Embodiment of this invention is applied, and the terminal connected to the network. It is a block diagram which shows the detail of a structure of a terminal. It is an overhead view which shows a network structure. It is a figure explaining the determination procedure of a GW-RP terminal. It is a figure which shows the determination method of a DHT terminal (distributed hash table terminal), and the response process with respect to the information request | requirement with respect to a DHT terminal. It is a figure explaining the process which acquires the information of a transfer destination terminal from a terminal group via a GW-RP terminal. It is a figure explaining the process of content transfer. It is a figure explaining the process of acquisition and deletion of content.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Terminal 3 Transmission network 11, 21 Application 31 DHT terminal network 32 Terminal group 111 Terminal basic information management part 112 Terminal performance information processing part 113 Terminal information acquisition process part 114 Content processing part 1111 Terminal state transition management part 1112 Terminal identification Information management unit 1121 Terminal performance information management unit 1122 Performance information determination processing unit 1131 DHT information search processing unit 1132 Terminal group information management unit 1141 Content division processing unit 1142 Content search processing unit 1143 Content acquisition processing unit 1144 Content deletion processing unit

Claims (6)

A method of transferring content between terminals on a P2P network in which a plurality of terminals transmit and receive arbitrary information and / or content data by autonomous distributed cooperation,
Configuring a terminal group by a terminal group having relevance to a content receiving terminal, and storing information on the terminal group in a distributed hash table configured by terminals selected according to the terminal function capability from the P2P network; ,
Sharing presence information of the content receiving terminal within a terminal group to which the content receiving terminal belongs;
A content transmitting terminal refers to the distributed hash table to determine which terminal group the content receiving terminal belongs to, and requests presence information of the content receiving terminal from the acquired terminal group;
When the content receiving terminal to be transferred is separated from the P2P network, the content is divided in consideration of the data size of the content to be transferred and the terminal capability of the terminal group, and the P2P network in the terminal group Distributedly deploying a copy of the content to terminals currently participating in
When the transfer target content receiving terminal joins the P2P network, the transfer target content receiving terminal rejoins the terminal group to which the transfer target content receiving terminal belongs, and is addressed to the terminal group with respect to the terminal group. Requesting the content, and if there is content information addressed to the terminal, acquiring the content and notifying the terminal group that the content has been acquired,
A P2P content transfer method. Each terminal participating in the P2P network periodically acquires the performance value of its own terminal;
A terminal having a capability equal to or greater than a predetermined threshold notifies the distributed hash table of the capability of the terminal, and if the terminal has a better capability than a terminal that already configures the distributed hash table, Registering as a terminal constituting a new distributed hash table;
The P2P content transfer method according to claim 1, comprising: Each terminal belonging to the terminal group exchanges the acquired performance value with other terminals in the terminal group together with the step of periodically acquiring the performance value of the own terminal;
The terminal having the highest performance value in the terminal group is determined as the GW-RP terminal, and the address of the determined GW-RP terminal is used as the address of the GW-RP terminal of the local terminal group stored in the distributed hash table. Registering
Selecting the new GW-RP terminal from within the terminal group when the GW-RP terminal leaves the P2P network, and registering the new GW-RP terminal in the distributed hash table;
The GW-RP terminal receives a request regarding a content receiving terminal of a terminal group to which the GW-RP terminal belongs from the content transmitting terminal, and performs flooding on the terminal group to which the GW-RP terminal belongs. Returning the acquired information to
Each terminal of the terminal group stores cache information of addresses of the GW-RP terminal and other terminals of the terminal group, and rejoins the same terminal group using the cache information when rejoining the P2P network And the stage of
The P2P content transfer method according to claim 1, comprising:   The address of the GW-RP terminal of the terminal group to which the content receiving terminal belongs is returned to the content transmitting terminal when the content transmitting terminal searches the distributed hash table by the identifier of the content receiving terminal. The P2P content transfer method described.   The method according to claim 1, further comprising the step of periodically detecting whether or not the terminals constituting the terminal group are participating in the network between the terminals constituting the link, and updating the presence information due to abnormal detachment of the terminals. The P2P content transfer method described.   The information having a relatively low change frequency is stored in the distributed hash table, and the information having a relatively high change frequency is managed by holding a copy of the information in the terminal group. The P2P content transfer method according to claim 1.

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