JP5376155B2 - Communication system, node, communication method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of reducing the throughput required for connecting new user equipment to an update information distribution system. <P>SOLUTION: The present invention is characterized in that a response message to a request message for retrieving a node to transmit desired information thereto is redirected after being delayed in accordance with distribution efficiency of the information at an own node. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a distribution system for providing content update information to a user apparatus when a distribution request is received from the user apparatus for content transmitted from a server.

  In recent years, mobile terminals such as mobile phones, PDAs, and in-vehicle terminals have become widespread, and there is an increasing demand among users for exchanging large-capacity content such as voice and video while moving. There is also a desire to distribute and use information generated by street corner monitoring cameras and various sensors on a network.

  In responding to such a demand, it is important to deliver content information to the user in real time without deteriorating the freshness of the content, especially when a large amount of content is distributed in various types.

  In response to such a demand, a system for distributing information that content has been updated has been studied. A method for efficiently distributing content update information to a large number of users in real time has been proposed.

  For example, in Patent Document 4, in a system that transmits and receives data between a plurality of nodes and distributes information, data is efficiently transmitted with reduced data loss due to traffic by delaying transmission according to a value unique to the node. Has been disclosed.

  On the other hand, several methods for constructing a distribution tree have been proposed in order to distribute information in order to efficiently distribute content update information to a large number of users in real time.

  For example, in Patent Document 2, a plurality of existing user devices that have received a distribution request from a user device that wishes to newly distribute their own CPU usage rate, memory usage rate, CPU specifications, physical proximity, survival A technique is disclosed in which evaluation information such as time is returned to a new user device, and the new user device compares and evaluates a plurality of received evaluation information and determines which existing user device to connect to. .

  Patent Document 3 discloses a technique for evaluating from the reception time and the connection order, and determining which existing user device is connected.

  Patent Document 4 discloses a technology that evaluates the number of hops and the speed of packet arrival and determines which existing user device is connected to.

JP 2001-045020 A JP 2005-252596 A JP 2005-85146 A JP 2004-246790 A

  However, since the technology of Patent Document 1 distributes data without considering a network configuration for efficiently transmitting data, it cannot efficiently transmit data. Also, in a situation where content is frequently created, modified, or disappeared in a ubiquitous network society, if the relationship between the server and the client changes frequently, the recombination of the topology becomes frequent and cannot be handled.

  Further, in each of the techniques of Patent Documents 2 to 4, a new user device issues a connection request to an existing user device, and the new user device receives responses from a number of existing user devices, and to which existing user device. Must be connected or evaluated. That is, a network configuration for efficiently transmitting data is considered, but the process of comparing and evaluating which existing user device is connected from a large number of responses is very difficult for a newly connected user device. It will give a load.

  Therefore, the problem to be solved by the present invention is to provide a technology that makes it possible to reduce the amount of processing required when a new user device connects to an update information distribution system.

The present invention for solving the above-described problems is a communication system configured with a tree structure having a distribution server that distributes the information for each information as a vertex, for searching for a node that transmits desired information. A response message to the request message is sent back with a delay in accordance with the distribution efficiency of the information in its own node.

The present invention for solving the above-mentioned problems is a node of a communication system configured by a tree structure having a distribution server that distributes the information as a vertex for each information, and searches for a node that transmits desired information. A response message to the request message for sending is sent back with a delay in accordance with the distribution efficiency of the information in its own node.

The present invention for solving the above problems is a communication method in a communication system configured with a tree structure having a distribution server that distributes the information for each information as a vertex, and includes a node that transmits desired information. A response message to the request message for searching is returned with a delay in accordance with the distribution efficiency of the information in its own node.

The present invention for solving the above-described problem is a communication system program having a tree structure with a distribution server that distributes the information for each information as a vertex. A response message to a request message for searching for a node to be transmitted is returned in a delayed manner according to the distribution efficiency of the information in its own node.

  According to the present invention, it is possible to reduce the amount of processing required when a user device newly participating in the update information distribution system connects to the update information distribution system.

It is a conceptual diagram which shows the network structure of the update information delivery system 1 which concerns on this invention. It is a block diagram which shows the structure of the user apparatus 100 disclosed in FIG. It is a conceptual diagram which shows the structure of the update information delivery server 200 disclosed in FIG. It is a conceptual diagram which shows the structure of the metadata database 122 disclosed in FIG. It is a conceptual diagram which shows the structure of the user apparatus information database 123 disclosed in FIG. 3 is a flowchart illustrating an operation of the user device 100 disclosed in FIG. 2 when the user device 100 transmits a search message. 3 is a flowchart illustrating an operation of the user device 100 disclosed in FIG. 2 when the user device 100 receives a search response message. 3 is a flowchart illustrating an operation of the user device 100 disclosed in FIG. 2 when the user device 100 receives a search message. It is a flowchart which shows operation | movement of the user apparatus 100 disclosed in FIG. 2 when the delay time calculation timer is notified in the user apparatus 100. It is a flowchart which shows operation | movement of the user apparatus 100 disclosed in FIG. 2 when the user apparatus 100 transmits the update graph participation request message. It is a flowchart which shows operation | movement of the user apparatus 100 disclosed in FIG. 2 when the user apparatus 100 receives an update graph participation request message. 3 is a flowchart illustrating an operation of the user device 100 disclosed in FIG. 2 when the user device 100 receives an update information message. 3 is a flowchart illustrating an operation of the user device 100 disclosed in FIG. 2 when the user device 100 transmits a content request message. 4 is a flowchart showing an operation of the update information distribution server 200 disclosed in FIG. 3 when the update information distribution server 200 updates content. 4 is a flowchart showing an operation of the update information distribution server 200 disclosed in FIG. 3 when the update information distribution server 200 receives a content request message.

  In the present invention, when receiving information distribution from a node that distributes desired information or a node that receives information distribution from this node, the node that receives the information distribution is searched, and the information distribution is performed from the searched node. It is a communication system set to receive.

  In order to explain the features of the present invention, it will be specifically described below with reference to the drawings.

  FIG. 1 is a conceptual diagram showing a configuration example of an update information distribution system 1 according to the present invention.

  The update information distribution system 1 includes a plurality of user devices 100 and an update information distribution server 200, and configures a logical network. One update information distribution system 1 is configured for one piece of content (information), and when there are a plurality of contents, a different update information distribution system 1 is configured on the logical network for each content. That is, by combining a plurality of update information distribution systems 1 on a logical network, a large-scale system that distributes update information of various contents to the user apparatus 100 can be constructed. The update information distribution system 1 has the update information distribution server 200 (n10) as the apex, the user information 100 is n8 and n11 under the update information distribution server 200, and the subordinates of n3, n44, and n11 are under n8. N22 are connected in a tree structure state.

  The user device 100 is connected to the update information distribution server 200 or one or a plurality of user devices 100. When update information is received from the connected update information distribution server 200 or one or a plurality of user devices 100, the update information is transferred to the user device 100 downstream in the update information distribution system 1. The user device 100 on the logical network can participate in the update information distribution system 1 by searching for desired content on the logical network and connecting to the update information distribution server 200 having the content.

  FIG. 2 is a block diagram illustrating a configuration of the user device 100 disclosed in FIG.

  The user device 100 includes a main control unit 110, a network interface 121, a metadata database 122, a user device information database 123, and a search result list 124.

  The main control unit 110 is a main part of a computer configured by a CPU, a RAM, an OS, and the like. The main control unit 110 includes a transmission / reception unit 111 configured as an operating program, a search function unit 112, and the like. A delay calculation unit 113, a delay buffer 114, a delay timer 115, an update information distribution system management unit 116, and a content client unit 117.

  FIG. 4 is a conceptual diagram showing a data configuration of the metadata database 122 disclosed in FIG. The metadata database 122 stores metadata related to the content of the update information distribution system 1 in which the device itself participates. Metadata is information attached to content, such as content ID, URI, title, creator, creation location, creation time, and keyword.

  FIG. 5 is a conceptual diagram showing the data structure of the user device information database 123 disclosed in FIG. The user device information database 123 stores user device information in the update information distribution system 1 for each content stored in the metadata database 122. The user device information is information necessary for transmitting / receiving a message to / from another user device such as a client ID, IP address, and port number that uniquely identifies the user device. In the tree structure of the update information distribution system, This is information on user devices above and below the device itself.

  The search result list 124 temporarily stores the search results of the update information distribution system 1 having the content desired by the device itself. The search result list 124 is used to determine which contents the update information distribution system 1 participates in, and is directly managed by the user.

  The transmission / reception unit 111 receives and processes a message from the update information distribution server 200 or another user device 100 via the network interface 121. If the received message is a search response message, the transmission / reception unit 111 sends the search response message to the search function unit 112. On the other hand, if the received message is a search message, the search message is sent to the search function unit 112. Further, when the received message is an update information distribution system participation request message, an update information distribution system participation request message is sent to the update information distribution system management unit 116. Furthermore, when the received message is an update information message, the transmission / reception unit 111 sends the update information message to the update information distribution system management unit 116. The transmission / reception unit 111 receives a message from the search function unit 112, the delay buffer 114, the update information distribution system management unit 116, or the content client unit 117, and the update information distribution server 200 that is a destination described in the message, or A message is transmitted to the other user apparatus 100 via the network interface 121.

  The search function unit 112 transmits a search message including the keyword of the desired content by broadcast to other user devices 100 existing on the logical network. The search message includes a search ID for uniquely identifying the generated search message, user device information, TTL (Time To Live) and the like in addition to the keyword. Furthermore, when the search function unit 112 receives a search response message from another user device 100, the search function unit 112 compares the metadata of the content included in the search response message with the search result list 124 and receives it in the search result list 124. If metadata is not included, the metadata is stored in the search result list 124. On the other hand, if the received metadata is included, the search response message is discarded. Furthermore, the search function unit 112 refers to the metadata database 122 when receiving a search message. When metadata matching the keyword included in the search message is found, the metadata is included in the search response message, and the search response message is passed to the delay buffer 114. Further, when the search message is received, the TTL included in the search message is referred to. When the TTL is not 0, the user device information database 123 is referred to, and the TTL is subtracted to other user devices 100. Forward search messages. At this time, the search message is not transmitted twice with reference to the search ID.

  The delay calculation unit 113 calculates a time for holding the search response message in the delay buffer 114 in response to the notification from the delay timer 115. This delay time is used so that a newly participating user apparatus 100 can connect to a position where the distribution efficiency is optimal on the logical network of the update information distribution system 1. The optimal distribution efficiency on the logical network of the update information distribution system 1 means that the tree structure for distribution can exist stably, the depth of the tree is shallow, and the connection that can be connected to the user device 100 is possible. The number is used up as much as possible (remaining number of connections), and indicates a configuration in which processing corresponding to each terminal capability of all user apparatuses 100 participating in the update information distribution system 1 is performed.

The calculation of the delay time includes, for example, the depth on the logical tree, the number of user devices that can be connected, the elapsed time since participation, and the like. Using this information,
Delay time = α x depth on logical tree ÷ (number of connectable user devices x elapsed time since participation)
Can also be calculated. Here, α indicates a parameter to be reflected in the delay time, but may be a weight for a parameter to be emphasized such as a depth on the logical tree, the number of connectable user devices, an elapsed time since participation, and the like. . In the above formula, the delay time is calculated to be shorter as the user device 100 has a smaller depth on the logical tree, a larger number of user devices that can be connected, and a longer elapsed time since participation. The number of user devices that can be connected is set to a number that matches the terminal capability of the user device 100. Further, the user device 100 that has received the search response message discards the search response message other than the earliest search response message. Therefore, the distribution efficiency is optimized on the logical tree of the update information distribution system 1 by performing such an operation. . The delay time may be calculated using at least one of the depth on the logical tree, the number of user devices that can be connected, and the elapsed time since participation.

As another calculation method of the delay time, the delay time can be calculated using a CPU processing load, a communication line load, or both. In order to return a search response message later as a node with less surplus power, a delay time arithmetic expression is defined so that the delay time increases as the CPU processing load or communication line load increases. For example,
Delay time = α × CPU processing load × communication line load. Here, α is a constant and gives a weight.

As another method of calculating the delay time, it took a process from receiving the search message until the search response message can be sent in order to return the search response message later to the node with less capacity. The delay time can also be calculated based on the time. The delay time arithmetic expression is defined so that the delay time becomes larger as the remaining power is smaller, that is, as the processing time is longer. For example,
Delay time = α x (Search response message transmission preparation completion time-Search message reception time)
Can be defined as Here, α is a constant and gives a weight.

As still another calculation method of the delay time, the delay time is calculated so that the search response message is returned later as the congestion degree of the route from the update information distribution server 200 through the logical tree to the update information reaching the own node is higher. You can also. The time taken for the update information to arrive at the own node by tracing the logical tree from the update information distribution server 200 is measured by some method, and a delay time arithmetic expression is defined based on this measurement value. For example,
Delay time = α x (Measured value of the time it takes for the update information to reach the local node from the update information distribution server through the logical tree)
Can be defined as Here, α is a constant and gives a weight.

  In order to measure the time taken for the update information to reach the node from the update information distribution server through the logical tree, after the search message is received, a message that follows the logical tree is transmitted to the update information distribution server 200. By receiving the response, the round trip time can be measured, and the delay time can be calculated based on the round trip time.

  The delay buffer 114 receives the search response message to be transmitted from the search function unit 112 and operates the delay timer 115 to wait for transmission for the delay time calculated by the delay time calculation unit. When the delay timer 115 expires, the delay buffer 114 transmits a search response message.

  The delay timer 115 raises an alarm to the delay calculation unit 113 every time a preset time elapses. Further, an alarm is given to the delay buffer 114 when the time specified from the delay buffer 114 has elapsed.

  The update information distribution system management unit 116 includes the information of the user device 100 itself to the user device 100 that has received the result selected by the user from the search result list 124 and has transmitted the selected content search response message. An update information distribution system participation request message is transmitted. On the other hand, when the update information distribution system participation request response message is received, the user device information included in the update information distribution system participation request response message is stored in a predetermined column of the user device information database 123. Further, when the update information distribution system management unit 116 receives the update information distribution system participation request message, the update information distribution system management unit 116 refers to the user device information database 123 and sends an update information distribution system participation request response message including connection information of the corresponding content. Create and send. The connection information included here includes, for example, information on the user apparatus 100 that transmits the update information distribution system participation request response message, and information on the next generation. Further, the update information distribution system management unit 116 additionally updates the information of the user device 100 that has transmitted the update information distribution system participation request message in the column below the first generation of the user device information database 123. Further, when the update information distribution system management unit 116 receives the update information message, the update information distribution system management unit 116 stores the metadata of the content included in the update information message in the metadata database. Further, the user apparatus information database 123 is checked, and if the user apparatus 100 is registered one generation lower with respect to the corresponding content, an update information message is transferred to the user apparatus 100.

  In response to an operation from the user, the content client unit 117 transmits a content request message to the update information distribution server 200 that owns the content. Further, upon receiving the content request response message, the content client unit 117 provides the user with the content included in the content request response message.

  FIG. 3 is a block diagram showing a configuration of the update information distribution server 200 disclosed in FIG.

  The update information distribution server 200 is connected to one or a plurality of user devices 100, and transmits update information to the connected user devices 100 when the owned content is updated. . The update information distribution server 200 includes a main control unit 210, a network interface 121, a metadata server database 222, a user device information database 123, a search result list 124, and a content database 225.

  The metadata server database 222 stores metadata of content that is an object for which the update information distribution server 200 notifies the user device 100 of update information. Metadata is information attached to content, such as content ID, URI, title, creator, creation location, creation time, and keyword.

  The content database 225 stores content that is a target for which the update information distribution server 200 notifies the user device 100 of update information. The content is, for example, text, sound, photo, video, or the like. When the content is updated, the metadata generation unit 218 is notified.

  Since the user device information database 123 and the search result list 124 are the same as the user device information database 123 and the search result list 124 of the user device 100, detailed description thereof is omitted.

  The main control unit 210 is a main part of a computer configured with a CPU, a RAM, an OS, and the like. The main control unit 210 includes a transmission / reception unit 211 configured as an operating program, a search function unit 112, The delay calculation unit 113, the delay buffer 114, the delay timer 115, the update information distribution system server management unit 216, the content server unit 217, and the metadata generation unit 218 are included.

  Since the search function unit 112, the delay calculation unit 113, the delay buffer 114, and the delay timer 115 are the same as the search function unit 112, the delay calculation unit 113, the delay buffer 114, and the delay timer 115 of the user device 100, Detailed description is omitted.

  When the metadata generation unit 218 receives a content update notification from the content database 225, the metadata generation unit 218 confirms the update content of the corresponding content in the content database 225 and updates the corresponding metadata in the metadata server database 222. Further, when the metadata generation unit 218 receives a content update notification from the content database 225, the metadata generation unit 218 notifies the update information distribution system server management unit 216 of the content update regarding the corresponding content.

  The update information distribution system server management unit 216 performs an operation equivalent to the function of the update information distribution system management unit 116 in the user device 100. Further, when the update information distribution system server management unit 216 receives a notification of content update from the metadata generation unit 218, the update information distribution system server management unit 216 refers to the corresponding metadata in the metadata server database 222 and sends an update information message including the metadata. create. Furthermore, the user apparatus information database 123 is referred to, and an update information message is transmitted to the user apparatus 100 one generation below.

  When the content server unit 217 receives the content request message from the user device 100, the content server unit 217 refers to the content database 225, creates a content request response message including the corresponding content, and transmits the content request message to the user device 100 that has transmitted the content request message. The content request response message is transmitted.

  Subsequently, the operation will be described.

  FIG. 6 is a flowchart showing an operation when the user apparatus 100 is operated to transmit a search message in order to search for the location of the desired content.

  When the operation is started, first, the transmission / reception unit 111 enters a state of waiting for communication from another user device 100 or the main control unit 110 in the user device 100 (hereinafter referred to as an idle state) (S300).

  When the search operation is started by an operation from the user (S301), the user device 100 transmits a search message including the keyword of the desired content to another user device 100 existing in the logical network (S302). After transmission, the state returns to the idle state (S300).

  FIG. 7 is a flowchart illustrating an operation when the user device 100 receives a search response message from another user device 100.

  When the user apparatus 100 receives a search response message that is a response to the search message transmitted by the user apparatus 100 during the idle state (S300) (S310), the user apparatus 100 refers to the search result list 124 (S311) and receives the received search response. It is checked whether or not the content metadata included in the message is already owned (S312).

  As a result of referring to the search result list 124 in step S312, if the content metadata included in the received search response message is not owned, the content metadata included in the received search response message is stored in the search result list 124. Save (S313) and return to the idle state (S300).

  On the other hand, as a result of referring to the search result list 124 in step S312, if the content metadata included in the received search response message is owned, the received search response message is discarded (S314), and the state returns to the idle state ( S300).

  FIG. 8 is a flowchart showing an operation when the user device 100 receives a search message from another user device 100.

  When the user device 100 receives the search message during the idle state (S300) (S320), the user device 100 refers to the metadata database 122 and does the user device 100 have metadata that matches the keyword of the content included in the received search message? Whether or not is confirmed (S321).

  If the result of confirmation in step 321 is that it has not been owned, the process proceeds to step S325.

  On the other hand, as a result of confirmation in step 321, if it is owned, it is set so that the newly participating user device 100 is connected to the position where the distribution efficiency is optimal on the logical tree of the update information distribution system 1. Wait for the delay time (S323).

  The search response message including the metadata that matches the keyword of the content included in the received search message is transmitted to the user apparatus 100 that has transmitted the search message (S324).

  Further, the TTL of the received search message is confirmed (S325), and if it is 0, it returns to the idle state (S300). When TTL is larger than 0 in step S325, the user apparatus information database 123 is referred to obtain information on another user apparatus 100 to which the search message should be transferred (S326). The search message is transferred according to the user device information obtained in step S326 by subtracting TTL (S327), and the state returns to the idle state (S300).

  FIG. 9 is a flowchart illustrating the operation of the user device 100 disclosed in FIG. 2 when the delay time calculation timer notifies an alarm in the user device 100.

  When the user apparatus 100 is in an idle state (S300) and the delay time calculation timer notifies an alarm (S330), the user apparatus 100 newly participates in a position where the distribution efficiency is optimal on the logical tree of the update information distribution system 1. The delay time set to connect the user device 100 is calculated (S331). The delay time is updated (S332), and the idle state is returned (S300).

  FIG. 10 is a flowchart showing the operation of the user device 100 disclosed in FIG. 2 when the user operates to participate in the update information distribution system 1 for the desired content.

  When the user device 100 is operated from the idle state (S300) to participate in the update information distribution system 1 of the content desired by the user (S340), the user device 100 refers to the search result list 124 and stores the metadata of the desired content. The notified user apparatus information is obtained (S341). Using the user device information obtained in step S341, an update information distribution system participation request message including information on the user device 100 itself is transmitted to the corresponding user device 100 (S342). When the update information distribution system participation request response message is received within a predetermined time (S343), the user device information database 123 is updated using the connection information of the corresponding content included in the update information distribution system participation request response message (S344). ) And return to the idle state (S300).

  FIG. 11 is a flowchart illustrating an operation of the user device 100 disclosed in FIG. 2 when the user device 100 receives an update information distribution system participation request message from another user device 100.

  When the user apparatus 100 receives an update information distribution system participation request message from another user apparatus 100 from the idle state (S300) (S350), the update information distribution system participation request response message including connection information of the corresponding content. And an update information distribution system participation request response message is transmitted to the user apparatus 100 that has transmitted the update information distribution system participation request message (S351). Further, the user apparatus information database 123 is updated using the user apparatus information of the user apparatus 100 that has transmitted the update information distribution system participation request message included in the received update information distribution system participation request message (S352), and idle Return to the state (S300).

  FIG. 12 is a flowchart illustrating an operation of the user device 100 disclosed in FIG. 2 when the user device 100 receives an update information message from another user device 100.

  When the user device 100 receives an update information message from another user device 100 from the idle state (S300) (S360), the user device 100 updates the metadata database 122 of the corresponding content (S361). Further, the user device information database 123 is referred to (S362), and it is confirmed whether the user device 100 one generation below exists (S363). As a result of step S363, when the user device 100 that is one generation below does not exist, it returns to the idle state (S300). As a result of step S363, if there is a user device 100 that is one generation lower, an update information message is transferred to the corresponding user device 100 (S364), and the state returns to the idle state (S300).

  FIG. 13 is a flowchart showing the operation of the user device 100 disclosed in FIG. 2 when the user operates to request a desired content body.

  When the user device 100 is operated from the idle state (S300) to request the content body desired by the user (S370), the user device 100 that owns the corresponding content with reference to the metadata database 122 is used. The device information is obtained (S371). A content request message is transmitted using the user apparatus information obtained in step S371 (S372). When a content request response message including a desired content body is received within a certain time (S373), the process returns to the idle state (S300).

  FIG. 14 is a flowchart showing the operation of the update information distribution server 200 disclosed in FIG. 3 when the content database 225 is updated in the update information distribution server 200.

  When the content database 225 is updated in the update information distribution server 200 from the idle state (S300) (S380), the update information distribution server 200 generates metadata of the updated content (S381). Further, the metadata server database 222 is updated using the generated metadata (S382). Further, the user device information database 123 is referred to (S383), and it is confirmed whether the user device 100 one generation below exists (S384). As a result of step S384, if the user device 100 of one generation below does not exist, it returns to the idle state (S300). As a result of step S383, if the user device 100 one generation below exists, an update information message is transmitted to the corresponding user device 100 (S854), and the state returns to the idle state (S300).

  FIG. 15 is a flowchart showing the operation of the update information distribution server 200 disclosed in FIG. 3 when the update information distribution server 200 receives a content request message from the user device 100.

  When the update information distribution server 200 receives the content request message from the user device 100 from the idle state (S300) (S390), the update information distribution server 200 refers to the content database 225 to obtain the corresponding content body (S391). A content request response message including the corresponding content body is transmitted to the user apparatus 100 that has sent the content request message (S392), and the state returns to the idle state (S300).

  Further, the update information distribution server 200 performs the same operation as the operation of the user device 100 disclosed in FIGS. 6, 7, 8, 9, and 11.

  6 to 15 is configured to be executed as a program that operates on a computer (main control unit) provided in advance in the user device 100 and the update information distribution server 200. be able to.

  In the above description, the connection to the user apparatus 100 has been mainly described. However, the update information distribution server 200 may operate as a node similar to the user apparatus 100.

  As described above, when the user apparatus 100 newly participates in the update information distribution system 1, the user apparatus that newly participates at a position where the distribution efficiency is optimal on the logical tree of the update information distribution system 1. 100, the search response message is transmitted without delay as much as the user device 100 in the optimum position among the user devices 100 already participating in the update information distribution system 1 that have received the search message so that the search message is connected. The user apparatus 100 participating in the update information distribution system 1 uses the search response message received first for each content, and discards the search response message received second and later, thereby newly updating the update information. It is possible to reduce the processing amount required when the user device 100 participating in the distribution system 1 connects to the update information distribution system 1. That, it is possible to provide a user device connecting means.

  Although the present invention has been described with the specific embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and is known so far as long as the effects of the present invention are achieved. It goes without saying that any configuration can be adopted.

DESCRIPTION OF SYMBOLS 1 Update information delivery system 100 User apparatus 110 Main control part 111 Transmission / reception part 112 Search function part 113 Delay operation part 114 Delay buffer 115 Delay timer 116 Update information delivery system management part 117 Content client part 121 Network interface 122 Metadata database 123 Use User information database 124 search result list 200 update information distribution server 210 main control unit 211 transmission / reception unit 216 update information distribution system server management unit 217 content server unit 218 metadata generation unit 222 metadata server database 225 content database

Claims (28)

For each information, a communication system configured with a tree structure having a distribution server that distributes the information as a vertex,
A communication system, wherein a response message to a request message for searching for a node that transmits desired information is returned in a delayed manner according to the distribution efficiency of the information in the node.   The node that transmitted the response message received first by the node that transmitted the request message is configured to transmit the information to the node that transmitted the request message. Communication system.   The delay is calculated using at least one of the position on the network of the node that returns the response message, the remaining number that can transmit the information to other nodes, and the elapsed time since belonging to the network. The communication system according to claim 1 or 2, characterized in that.   The communication system according to claim 3, wherein the delay is set according to a position on the network ÷ (the remaining number × the elapsed time).   The communication system according to claim 1, wherein the delay is calculated using measured values of a CPU processing load and a communication line load of the own node.   3. The delay according to claim 1, wherein the delay is calculated by using a time required for processing from when the request message is received until the response message can be transmitted. Communications system.   The communication system according to claim 1, wherein the delay is calculated using a time taken for the information to reach the node from a node that is a source of the information.   2. The delay is calculated from a round trip time measured by using a response of a message that is transmitted to a node that is a source of the information after receiving the request message and that follows the logical tree. Or the communication system of Claim 2.   The communication system according to any one of claims 1 to 8, wherein when the update information of the information is received, the update information is transmitted to the set node. For each information, a node of a communication system configured with a tree structure with a distribution server that distributes the information as a vertex,
A node characterized in that a response message to a request message for searching for a node that transmits desired information is returned in a delayed manner in accordance with the distribution efficiency of the information in its own node.   The node that transmitted the response message received first by the node that transmitted the request message sets the information to be transmitted to the node that transmitted the request message. Nodes.   The delay is calculated using at least one of the position on the network of the node that returns the response message, the remaining number that can transmit the information to other nodes, and the elapsed time since belonging to the network. The node according to claim 10 or 11, characterized in that:   The node according to claim 12, wherein the delay is set according to a position on the network ÷ (the remaining number × the elapsed time).   The node according to claim 10 or 11, wherein the delay is calculated using measured values of a CPU processing load and a communication line load.   The node according to claim 10 or 11, wherein the delay is calculated by using a time required for processing from receiving a request message until a response message can be transmitted.   The node according to claim 10 or 11, wherein the delay is calculated using a time taken for the information to reach the node from a node that is a source of the information.   11. The delay is calculated from a round trip time measured using a response of a message that is transmitted to a node that is a source of the information after receiving the request message and traces on the logical tree. Or the node according to claim 11.   The node according to any one of claims 10 to 17, wherein when the update information of the information is received, the update information is transmitted to the set node. For each information, a communication method in a communication system configured with a tree structure having a distribution server that distributes the information as a vertex,
A communication method characterized in that a response message to a request message for searching for a node that transmits desired information is returned in a delayed manner in accordance with the distribution efficiency of the information in the node.   The node that transmitted the response message received first by the node that transmitted the request message is configured to transmit the information to the node that transmitted the request message. Communication method.   The delay is calculated using at least one of a position on the network of a node to which the response message is returned, a remaining number that can transmit the information to another node, and an elapsed time since belonging to the network. The communication method according to claim 19 or 20.   The communication method according to claim 21, wherein the delay is set according to the position on the network / (the remaining number x the elapsed time).   21. The communication method according to claim 19, wherein the delay is calculated using measured values of a CPU processing load and a communication line load.   21. The communication method according to claim 19, wherein the delay is calculated using a time required for processing from reception of a request message until a response message can be transmitted. .   21. The communication method according to claim 19 or 20, wherein the delay is calculated using a time taken for the information to reach the node from a node that is a source of the information.   20. The delay is calculated from a round trip time measured by using a response of a message that is transmitted to a node that is a source of the information after receiving the request message and traces on the logical tree. Or the communication method of Claim 20.   27. The communication method according to claim 19, wherein when the update information of the information is received, the update information is transmitted to the set node. For each information, in the information processing apparatus of the communication system configured with a tree structure with the distribution server that distributes the information as a vertex ,
A program for executing a process of returning a response message to a request message for searching for a node that transmits desired information with a delay in accordance with the distribution efficiency of the information in the node.

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