JP4232593B2 - Information terminal equipment - Google Patents

Description

  The present invention relates to an information terminal device that shares content in a network, an information sharing method, and a P2P system using the same.

  Conventionally, in order to “provide an automatic deletion device that can automatically delete a received content from a storage device and effectively use the storage device”, when the content is output, There is a content automatic deletion device that sets a storage period of content and deletes the content after the content reaches the storage period. (See Patent Document 1, Abstract)

JP 2001-43168 A

  However, the content automatic deletion device of Patent Document 1 relates to the lifetime of the received content, and does not take into consideration any points regarding the lifetime of the content at the transmission destination by transmitting the received content to another device. It has not been.

  Therefore, the subject of this invention is providing the information terminal device suitable for content sharing, the information sharing method, and the P2P system using the same in view of the point.

  In order to solve the above problems, the present invention provides the following information terminal device, information sharing method, and P2P system.

  The information terminal device, the information sharing method, and the P2P system of the present invention receive content that is given a lifetime, change the lifetime, and transmit the content that is given a lifetime to another information terminal device It is characterized by.

  Due to such characteristics, since the received content is given a lifetime, the lifetime can be set on the transmission side, and the content distribution can be controlled on the content distribution side. Further, since the survival time is changed, it is possible to set the survival time according to the information terminal device. In addition, since the content given the lifetime is transmitted to another information terminal device, the lifetime of the content at the transmission destination can be controlled. As a result, it is possible to control the lifetime in the entire P2P system, which is suitable for content sharing.

  According to the present invention, an information terminal device, an information sharing method, and a P2P system suitable for content sharing can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. Hereinafter, in this embodiment, an ad hoc network forming a P2P network will be described.

  Note that P2P is a mechanism for sharing information among a large number of nodes, and has a feature that other nodes search for information disclosed on the nodes as they are. In searching for information existing on another person's node, at least the CPU resource to be searched must be used. Also, since communication naturally occurs, the network resource on the searched side is also used. In addition, search efficiency is greatly deteriorated in a large-scale P2P network only by publishing on a node. Information cannot be acquired when the node is offline. For this reason, a method of improving the sharing efficiency by using the memory on the node as a cache memory can be considered. These are proposed from the mutual idea that each participating P2P node provides an easy-to-use information sharing environment instead of providing some resources in P2P. This is because the surplus resources of each node surpass the large-scale centralized server due to a dramatic increase in the amount of memory installed. For example, enormous investment was required to realize Napster with a centralized server, but the Napster system can be realized with only a few PCs by collecting some resources of tens of millions of PCs. It was. In other words, the essence of P2P is to create a comfortable environment by providing resources that do not bother you. Further, if the centralized server is eliminated and converted to P2P, various advantages that cannot be realized by the centralized server can be enjoyed.

  An ad hoc network is a network formed by nodes existing on the spot. With recent improvements in mobile related technology, a method of directly communicating at a relatively short distance of about several tens of meters has begun to attract attention as a high-speed, low-cost and highly flexible communication method.

  FIG. 1 is an explanatory diagram regarding a dynamic network in an ad hoc network, and this network forms a P2P network. The P2P network refers to a group of nodes that can share information by an information transmission function and an information search function. In the description, the direct communication area refers to an area that can be communicated in short-range wireless communication such as a wireless local area network (LAN) or infrared communication, and includes other nodes in the direct communication area. Information can be sent. In other words, bidirectional communication is possible when they are included in the direct communication area. Note that the direct communication area is a conceptual area, and it is not necessary to reflect the area where radio actually reaches.

  In FIG. 1, 101 to 123 belong to state 1, and 151 to 172 belong to state 2. State 1 indicates a certain time, and state 2 indicates a state in which time has elapsed from state 1. Reference numerals 101 to 105 and 151 to 155 denote nodes, respectively. Reference numerals 111 to 115 and 161 to 165 denote direct communication areas, respectively. In state 1, the directly communicable areas 111 and 112 of the nodes 101 and 102 include the nodes of each other and can communicate with each other. Similarly, the nodes 102 and 103 can communicate with each other. Therefore, the nodes 101, 102, and 103 form a P2P network. Since the nodes 104 and 105 do not include other nodes in the directly communicable area, they cannot communicate. Therefore, the nodes 104 and 105 independently form the P2P networks 104 and 105, respectively.

  Next, state 2 after a certain time has passed from state 1 will be described. In state 2, nodes 101 and 105 have moved to the locations of nodes 151 and 155, respectively. In state 2, since the node 101 forming the P2P network 121 is directly removed from the communication area, the P2P network 121 is newly reconfigured as the P2P network 171. Similarly, since the nodes 151, 154 and 155 are directly added to the communication area, the P2P network 172 is newly reconfigured by the respective nodes. In the reconfiguration of the P2P network, the withdrawal process / subscription process of the members configuring the P2P network is performed.

  FIG. 21 is an explanatory diagram of nodes. In FIG. 21, 2101 is a CPU, 2102 is a recording unit such as a memory or a hard disk, 2103 is an interface for connecting to a network or directly connected to another node, 2104 is an input unit such as a keyboard or touch panel, and 2105 is a screen. And an output unit such as a speaker. The input unit 2104 may be connected to a module that can acquire the traveling direction and latitude / longitude of the node.

  The node recording unit 2102 has a memory internal configuration as shown in FIG. FIG. 2 is an explanatory diagram of the memory configuration of the node.

  Reference numerals 210, 220, and 230 denote nodes. The node has a public memory area 211 and a cache memory area 212. The public memory area is an area where contents created by a node are registered and released. Other nodes can acquire the content registered in the public memory area unless there is a special setting. The cache memory area is an area for storing content created by other nodes. Other nodes can obtain the content stored in the cache memory area unless there is a special setting. In FIG. 2, the node 210 publishes contents 215 to 217. For example, when the node 230 acquires the content 217, the content is stored in the cache memory area 232. When the node 220 transmits content to the node 210, the content is stored in the cache memory area 212. That is, the public memory area is an area where original content is stored, and the cache memory area is an area where copied content is stored. In addition, a configuration in which the original content is not stored in the public memory area or a configuration in which there is no public memory area may be used. In this case, similar functions are implemented jointly with other nodes, but conceptually similar to FIG. Become.

  Here, the content can be referred to by the content holder and needs to be efficiently referenced from many nodes. The former is implemented as existence guarantee and the latter is implemented as sharing efficiency. The existence guarantee may be referred to by holding it in a node used by the content holder. As for the sharing efficiency, it is only necessary to make a wide copy other than the node used by the content holder and improve the sharing efficiency as a P2P network. When these are considered with one terminal, they are in a competitive relationship in the use of memory, and it becomes difficult to achieve both when there is a limit on the amount of memory used. Therefore, if the memory is divided into two for existence guarantee and sharing efficiency and the contents are clarified at the time of registering the contents in the memory, there is an effect that management in each memory becomes easy. In this embodiment, the existence guarantee memory is called public memory, and the shared efficiency memory is called cache memory.

  FIG. 3 is an explanatory diagram of contents. The content includes metadata 310 and content data 311. Reference numeral 310 denotes metadata that describes the content. The content ID 311 is an ID for uniquely identifying content in all P2P networks. The issuer ID 312 is an ID for determining the issuer of the content in the same manner as the content ID. The content type 313 indicates the type of content, such as news or sports. The content action 314 is one of characteristic data in the present embodiment, and indicates processing for the survival time. Details of the content action will be described later. The survival time 315 indicates a time during which the content is not deleted, and is indicated by a date / time such as year / month / day / hour / minute / second, or a remaining time of 5 minutes. Content whose lifetime has passed is erased from the memory by the node that holds the content. Note that erasing from the memory includes not only deleting the content but also making the content unreproducible. The survival upper limit time 316 is one of characteristic data in the present embodiment, and indicates the upper limit time for resetting the survival time. Details of the survival upper limit time will be described later. The free area 317 is an area not corresponding to the above 311 to 316.

  The survival time may be set at a time when the survival time is scheduled to disappear, or may be set as a time when the node can survive after receiving the content. When the survival time is set by time, when the content action 804 described below is performed and the content written in the cache 820 is transmitted to another node, it is not necessary to reflect the elapsed time after reception in the content, and the content can be transmitted as it is. effective. Setting the survival time in terms of time has the effect of operating correctly even if the node clock is inaccurate.

  320 is content data of the content. Content data refers to the substance of the content, for example, a news article refers to an article. Further, as a feature of the present embodiment, the content may have an access control attribute, and the metadata 311, 312, 313, 314, 316 other than the lifetime 315 and the free 317 may be write-protected. In this case, alteration of the content is prevented.

  FIG. 4 shows contents received and collected and selection of the contents. Reference numeral 410 denotes a request source node, and 420 and 430 denote request destination nodes. In FIG. 4, the node 410 requests content, searches for content that matches the request, and the nodes 420 and 430 transmit the content to the node 410. Search results including contents are transmitted from the open memory areas 421 and 431 and the cache memory areas 422 and 432. The received search result is stored in the cache memory area 421 of the node 410.

  When the content data capacity is larger than the cache memory area, it is necessary to discard unnecessary contents. Reference numeral 413 denotes an area for holding necessary contents, and reference numeral 414 denotes an area for holding unnecessary contents. If the type of content is average and the collection tendency of nodes is not significantly biased, most of the content is unnecessary content, and only a part of the content is necessary. That is, as time elapses, content according to the node setting is accumulated in 413. On the other hand, in 414, content replacement always occurs from the time when the cache overflows. That is, the content held by the node is occupied by content that strongly depends on the preference of the search source node and content that has not been deleted by accident.

  This is an essential problem, and it is impossible to predict and provide necessary content to an unknown node. Therefore, a restriction of minimizing the survival time is added to the content. If the lifetime of content is minimal, the cache is relatively unlikely to overflow. However, especially in an ad hoc environment, it is difficult to expect transportation from one node to another in a wide area because of its short survival time. The present invention for solving this problem will be described with reference to FIGS.

  The node content collection setting will be described with reference to FIG. The setting is divided into items of the policy 501, that is, active collection 511, negative collection 521, collection rejection 531, major classification 502, middle classification 503, and minor classification 504. The active collection is a setting in which the degree of preference is high and content is actively collected. The negative collection is a setting in which content is not actively collected, but is stored in the cache memory area for as long as possible when content targeted for negative collection is received. The collection refusal is a setting that significantly shortens the survival time when content that the user does not want to collect is collected. The user who collected the node wants to discard the node immediately after reception. However, in the ad hoc network, if the node is discarded immediately after reception, the content cannot be propagated to a wide area. Therefore, the survival time is greatly shortened so that the user's node that does not want to be collected does not survive for a long time, and another node is given an opportunity to propagate the content. The major classification, middle classification, and minor classification each represent a classification of the content type, and the classification of the content type becomes finer in the order of major classification, middle classification, and minor classification. In this example, content corresponding to active collection is stored in a non-discarded area of the cache memory area when received. Alternatively, a search request may be explicitly sent to another node. When the content corresponding to the negative collection is received, it is stored in an area of the cache memory area that is relatively difficult to discard. The content corresponding to the collection refusal is stored in a relatively easily discarded area of the cache memory area.

  Next, the content type 313 used in the content collection setting will be described with reference to FIG. Similar to the content collection setting, the content type includes a large classification 601, a medium classification 602, and a small classification 603 related to preference data. In this example, it can be seen that the major category is shopping, the middle category is discount, and the minor category is gasoline. In the search by the node, for example, only the large classification may be used, and in that case, the comparison is performed only by the large classification of the content type.

  Next, a cache garbage collector that automatically discards contents when the lifetime 315 has elapsed will be described with reference to FIG. The cache garbage collector is a management function associated with the cache memory area.

  In FIG. 7, reference numerals 701 to 716 denote the state 1, and reference numerals 751 to 766 denote the cache garbage collector and the cache memory area in the state 2. In this example, state 2 indicates a state after 20 minutes from state 1. In state 1, all the lifetimes of the contents 711 to 716 are after the current time of the cache garbage collector 701 and are not deleted. In state 2, the lifetime of the contents 761, 764, 765 is before the current time of the cache garbage collector 751, and the lifetime is past the current time, so that it becomes a target of disposal, and the cache garbage collector 751 has contents 761, 764 and 765 are deleted.

  The processing at the time of content reception and the regular processing of the node that implements the above processing will be described with reference to FIG. Reference numerals 801 to 806 denote a series of flow of content reception processing. Reference numerals 811 to 815 denote a series of flow of periodic processing by the cache garbage collector. When the node receives the content (801), it checks whether or not a callback is registered (802). Callback registration refers to registering in advance processing to be performed when a condition is satisfied. In this example, receiving the content may be a condition for establishing 802, or a specific content type or issuer ID may be the forming condition for 802. When the condition 802 is established, the corresponding callback process is performed (803), and the process is terminated (806). When the callback process is not performed, the node performs the content action process (804). Although the callback registration process is not essential, there is an effect that the process according to a specific content type or issuer ID can be individually set by performing this registration process. Details of the content action process will be described later. Next, the data is written in the cache memory area 820 (805), and the process is terminated (806). In addition, a timer that fires periodically in parallel is started (811). Since the process 811 is performed when the node is activated, the process 811 is normally performed before the process 801. The timer is started, and when the set time of the timer is exceeded, the timer is fired (812). Next, the lifetime 315 of all contents in the cache 820 is confirmed (813). If the lifetime has passed (814), the corresponding contents are deleted from the cache (815). Steps 813 to 815 are repeated by the number of contents.

  Note that the content written in the cache 820 is retransmitted to another node in response to a transmission request from another node or unilaterally. In addition, when the survival time is set by time, it is necessary to subtract the elapsed time from the survival time when content is transmitted to another node. However, if the survival time is set by time and the elapsed time is not reflected, it may be transmitted as it is to another node.

  The content action 804 will be described with reference to FIGS. The content action includes a type action 910 and a state action 920. When the content action is started (901), first, the type action 910 is started (911). In the type action, the survival time is calculated using the type action 1010 described in the content action 314 (912). The calculation is performed for each action target 1001. The determination method 1002 is a match between the classifications of the content type 500 and the node type 600. If they match, the process 1003 for the survival time is executed. For example, when the content type matches the node type positive collection classification, the major classification match is added for 2 minutes, the middle classification match is 4 minutes, and the minor classification match is added for 6 minutes. In the case of negative collection, 1 minute is added to the major classification, 2 minutes is matched to the middle classification, and 3 minutes is added to the survival time in the minor classification. In the case of refusal, the survival time is greatly shortened, for example, −5 minutes. Otherwise, the survival time is not changed. If the survival time is later than the survival time upper limit 316, the survival time is set as the survival time upper limit. Next, the obtained survival time is set as the content survival time 315 (913), and the processing of the type action is terminated (914).

  Next, a state action is started (921). In the state action, the survival time is calculated for each item of the action target 1101 in the node state 1100 (922). Since the received content is assigned a terminal state, which is the state of the terminal such as the moving direction and moving speed, the node state of the node is detected, and the lifetime is determined based on the detected terminal state and the detected node state. change. In this example, since the moving direction 1102 is 180 °, d = 1.0, and since the moving speed is 40 km / h, the additional time is 10 minutes. Thus, the survival time is added for 10 minutes. The calculated survival time is reset to the survival time 315 (923), and the state action processing ends (924). Thus, all the processes are completed (925).

  Here, the reason why the upper limit of the survival time is set is as follows. When the survival time is extended each time copying is performed between nodes, there is a problem that the content survives more than necessary. If content with a lifetime set to 10 minutes is added by receiving 1 minute, if it is propagated in 100 nodes in 10 minutes in order, the remaining lifetime will be 90 minutes. For example, in an advertisement such as a time service with an expiration date of 20 minutes There are cases where content creators do not meet the intentions. Therefore, if the upper limit of the survival time is set, the intention of the content creator can be appropriately reflected. The upper limit of the survival time may be a time.

  In addition, if the action target does not fall into any of the active collection, negative collection, or collection refusal, the processing for the survival time is not performed, but this is not restrictive. For example, -1 minute may be used. In this way, it is possible to erase the less important content at an early stage and use the memory capacity more effectively.

  In FIG. 9, both the type action and the state action are performed, but only one of the action processes may be performed. If only one action is set, a simpler system can be constructed.

  If a method using the content action as described above is used, the content has a characteristic that the lifetime is short and it is difficult to occupy the public cache memory, the content passes through a node that does not require the content, and the content is transferred to the node that requires the content. Easy to communicate.

  A first embodiment using this method will be described. The first embodiment is intended for an ad hoc network in which a distribution source provides an advertisement and conveys it to a highly interested node.

  FIG. 12 shows the configuration of an ad hoc network in which each node moves. Since each node periodically searches for information, the advertising content published by 1201 propagates to nodes 1211, 1212. However, information does not propagate to nodes 1221 to 1223 that are not connected by the network. In FIG. 12, the interest in the advertising content of this example decreases in the order of A type, B type, and C type.

  At this time, information propagation is considered using the content type and node type as shown in FIG. When the node receives the content, the content action process is started (1301). If the node that received the content is the A type, the content type 500 and the node type 600 match (1311). Therefore, the survival time is extended (1312), and the survival time 315 is reset (1314). In this example, only the type action 1310 is performed, and the state action 1320 is not executed because it is not described in the content action 314. Therefore, when the type action process ends, the action process ends (1302). If the node that received the content is a B / C type, the survival time is set short.

  With the above flow, information propagates as shown in FIG. Reference numerals 1402 and 1403 indicate how information propagates through an area with many A type nodes. In an area where there are many B / C type nodes, the survival time is short and information is difficult to propagate. Then, it becomes easy for advertisement content to gather in the area where A-type nodes like the area 1404 gather.

  As an example in which the first embodiment is applied more specifically, for example, 1401 is a car dealership, A is a person who is highly interested in cars, B is a normal person, and C is a person who is not interested in cars To do. When 1401 provides an advertisement for a new car test ride to nearby nodes, the advertisement propagates along routes 1402 and 1403 as each node moves. In the area 1404 where A gathers, information can be gathered naturally if the survival time is appropriately set. At this time, the information passes through not only A but also B and C.

  Next, a second embodiment using this method will be described. The second embodiment is intended to control an area in which an advertisement is provided by a distribution source and further the advertisement is transmitted in an ad hoc network.

  FIG. 15 shows a configuration of an ad hoc network in which each node moves along a route to some extent. Since each node periodically searches for information, the advertising content published by 1503 propagates from 1511 to 1515. However, information is not propagated to the nodes 1521 that are not connected by the network. In FIG. 12, the interest in the advertising content of this example decreases in the order of A type, B type, and C type.

  At this time, the propagation of information is considered using the content type, node type, state action, and node state as shown in FIG. When the node receives the content, the content action process is started (1601). First, the type action 1610 is executed. The content type 500 and the node type 600 are compared (1611), and if the types match, 1612 is executed, and if the types do not match, 1613 is executed. In this example, the A type node increases the survival time by one minute, and the B type and C type nodes decrease the survival time by one minute. Next, the obtained survival time is reset as the survival time 315 (1614).

  Next, the state action 1620 is executed. Using the processing method of the state action 1020, the survival time calculation processing 1630 is executed using each parameter of the node state 1100. In this example, first, the direction of the node is obtained (1631), and the value of t is obtained from 1632, 1633, and 1634, respectively. Next, in the case of 1632, the processing of 1637, 1638, and 1639 is executed using the value of the node state in 1635, respectively. When 1633 and 1634 are executed, the processing of 1637, 1638, and 1639 is executed in 1636 using the value of the node state. Next, the survival time is calculated from the values of t and v (1640) and reset to the survival time 315 (1621). Thus, the action process ends (1602).

  With the above flow, information propagates in a range close to the area 1701 shown in FIG. The distribution source 1702 can efficiently propagate the content to be erased in a short time via a node other than Type A.

  As an example in which the second embodiment is applied more specifically, for example, when 1702 is a gas station and the road facing the road cannot be crossed to the right, if the paper is north, the advertising effect on the car coming from the north is low . In this case, if the content received directly from the distribution source is recorded in the node state as having passed the distribution source, the vehicle that has gone north by the vehicle that has passed has greatly shortened its survival time by the state action, and the vehicle that has not passed A car that travels south can also prevent the information from spreading to the north if the state action is used to significantly reduce the survival time. In addition, if the car that has not passed through the car goes north, the survival time can be extended, and the car that passes the car southward can extend the survival time, so that the information can be promoted to the south. Furthermore, if the upper limit of the survival time is appropriately set according to the time, it is possible to prevent information from moving south more than necessary.

  Next, a third embodiment using this method will be described. The third embodiment is intended to share information within a certain area in an ad hoc network.

  FIG. 18 shows a configuration of an ad hoc network in which each node moves. Each node can detect its own position by communicating with GPS (Global Positioning System), short-range wireless communication, and a wireless base station. Since each node periodically retrieves information, the content published by the node is propagated to all connectable nodes. In FIG. 18, the interest in the content published by a certain node decreases in the order of A type, B type, and C type. Reference numeral 1810 denotes an area where information is desired. When 1811 publishes content, 1812 receives the content. 1813 may receive content when the ad hoc network is reconfigured.

  At this time, the propagation of information is considered using the content type, node type, state action, and node state as shown in FIG. When the node receives the content, the content action process is started (1901). First, the type action 1910 is executed. The content type 500 and the node type 600 are compared (1911). If the types match, 1912 is executed, and if the types do not match, 1913 is executed. In this example, the survival time is shortened by 1 minute for the A type node, and the survival time is shortened by 1 minute for the B type and C type nodes. Next, the obtained survival time is reset as the survival time 315 (1914). Next, the state action 1920 is executed. Using the processing method of the state action 1020, the survival time calculation processing 1930 is executed using each parameter of the node state 1100. In this example, first, the position of the node is determined (1931), 1932 is executed if it is outside the area, and 1933 is executed if it is inside the area, and the value of t is obtained. Next, the value of t is added to the survival time (1934), and the survival time 315 is reset using the obtained value (1921). Thus, the action process ends (1902).

  With the flow as described above, information propagates in a range close to the area 2010 shown in FIG. The distribution source 2011 can efficiently hold content that is deleted in a relatively short time via a node other than type A in the same area. Further, for example, when received within 2020, it is set within or near the area in 1931, and the time shorter than 1932 is added to the survival time, so that the possibility that content exists in the area 2010 can be improved.

  As an example in which the third embodiment is applied more specifically, for example, when 2010 is a complex facility composed of a theme park and a shopping mall, information for people in the facility is not required outside the complex facility. is there. At this time, if information is provided in the facility by short-range wireless, an area is set by latitude and longitude, etc., and if the survival time of the information is set to be long within the area and the survival time is set to be short outside the area, Has a high probability, and the region 2020 has a lower probability than 2010 but can propagate information with a certain probability.

  Regarding the above propagation method, when a plurality of the same nodes repeatedly receive content in order, there arises a problem that the same content action is repeatedly performed. Therefore, a unique ID is assigned to each content, and when content with a certain ID is received for the first time, the content ID is stored in the memory of the node, and when the next content is received, has the same content been received in the past? If the same content is received in the past, the content may be deleted immediately.

  The above is based on a P2P network composed of ad hoc networks formed by nodes existing on the spot due to spatial restrictions such as radio propagation range. For example, in an environment such as the Internet where all nodes can be connected A group that is dynamically formed from a group of nodes may be part of the ad hoc network. For example, when a group of nodes gathered on a bulletin board on a network is used as a group and a P2P network communicable only within the group is configured, the group is dissolved, a group member is changed, another group is formed, etc. Then, it becomes the same as the ad hoc network formed from spatial restrictions.

  In addition, when searching for information from other nodes, it is periodically performed to make simple settings. However, the present invention is not limited to this. For example, information may be set to be searched in a time zone where communication traffic is not congested such as at midnight. In this way, trouble due to congestion of communication traffic can be avoided.

  According to the above embodiment, since the content given the lifetime is received, the lifetime can be set on the transmission side, and the content distribution can be controlled on the content distribution side. In addition, since the survival time given to the received content can be changed, it is possible to set the survival time according to the received preference of the information terminal device. In addition, since the content given the lifetime is transmitted to the other information terminal device, it is possible to control the lifetime in the other information terminal device of the transmission destination.

  As a result, in the P2P system, the content given the lifetime is distributed, so that the memory of the information terminal device can be prevented from being punctured. In addition, since the survival time is changed according to the user's preference of each information terminal device, even if content that does not match the preference needs to be stored in the user's memory for content distribution, The time can be changed shortly, and contents unnecessary for the user can be deleted early.

  Also, when changing the lifetime of received content, even if it can be shortened, if it cannot be deleted immediately, it will be deleted immediately after reception by a person who does not meet the user's preference. The situation of not distributing can be prevented.

  According to the above embodiment, in the information terminal device, it is possible to effectively collect information without disclosing information such as user preferences to others. In addition, information sharing via a terminal that does not match preferences is possible.

It is a figure which shows the structure of an ad hoc network. It is the figure which showed the memory structure of a node, and transmission / reception of the information with another node. It is a figure which shows the structure of a content. It is the figure which showed the memory inside at the time of searching to all the nodes which can be connected. It is a figure which shows the structure of a node type. It is a figure which shows the structure of a content type. It is explanatory drawing of the cache garbage collector which erase | eliminates the content for which the lifetime was complete | finished. It is explanatory drawing of this Embodiment. It is a flowchart which performs a content action. It is a figure which shows the structure of a content action. It is a figure which shows the structure of a node state. It is a block diagram of the 1st Example in an ad hoc network. It is a flowchart of the content action of a 1st Example. It is the figure which showed the effect of the 1st Example. It is a block diagram of the 2nd Example in an ad hoc network. It is a flowchart of the content action of a 2nd Example. It is the figure which showed the effect of the 2nd Example. It is a block diagram of the 3rd Example in an ad hoc network. It is a flowchart of the content action of a 3rd Example. It is the figure which showed the effect of the 3rd Example. It is explanatory drawing of a node (information terminal device).

Explanation of symbols

801 ... Content reception step, 802 ... Callback registration determination step, 803 ... Callback processing step, 804 ... Content action processing step, 805 ... Cache write step, 806 ... Process end step, 811 ... Periodic firing timer start step, 812 ... Timer firing step, 813 ... Survival time confirmation step, 814 ... Survival time elapsed determination step, 815 ... Delete processing step, 820 ... Cache

Claims (8)

A receiving means for receiving the content given the survival time;
Survival time changing means for changing the survival time given to the content received by the receiving means;
Transmitting means for transmitting the content given the survival time to another information terminal device;
An erasing unit for erasing the content after the lapse of the lifetime changed by the lifetime changing unit;
An information terminal device having
The information terminal device comprises node type storage means for storing the node type that is the type of content,
The content received by the receiving means is given a content type that is the type of content,
The survival time changing means changes the survival time based on a content type assigned to the received content and a node type stored in the node type storage means. . The information terminal device according to claim 1 ,
The node type storage means stores a positive collection node type which is a node type to be actively collected,
The information terminal device characterized in that the survival time changing means extends the survival time for a first predetermined time when the content type matches the positive collection node type. The information terminal device according to claim 2 ,
The information terminal apparatus characterized in that the survival time changing means shortens the survival time to a second predetermined time when the content type does not match the active collection node type. The information terminal device according to claim 2 ,
The node type storage means stores a negative collection node type having a lower degree of collection than the positive collection node type,
The lifetime changing means extends the lifetime for a third predetermined time shorter than the first predetermined time when the content type matches the negative collection node type. . The information terminal device according to claim 3 ,
The node type storage means stores a collection rejection node type that is a node type for which collection is to be rejected,
The survival time changing means shortens the survival time to a fourth predetermined time longer than the second predetermined time when the content type matches the collection refusal node type. . The information terminal device according to claim 1 ,
Node state detection means for detecting the node state that is the state of the information terminal device,
The received content is given a terminal state that is the state of the information terminal device,
The survival time changing means changes the survival time based on the terminal state given to the received content and the node state detected by the node state detection means. . The information terminal device according to claim 6 ,
The node state includes the moving direction or moving speed of the information terminal device. Receiving means for receiving the content, storage means for storing the content, transmission means for transmitting the content, survival time changing means for changing the lifetime of the content, and erasing means for erasing the content,
The receiving means receives the content given the survival time,
The storage means includes received content storage means for storing content received by the receiving means, and non-public content storage means for storing content that is not desired to be disclosed to other information terminal devices,
The survival time changing means changes the survival time given to the content stored in the received content storage means,
The transmission means performs a search from another information terminal device, and when the content corresponding to the search is stored in the received content storage means, the content provided with a lifetime is sent to the other information terminal. If it is transmitted to the device and stored in the private content storage means, the content is not transmitted to the other information terminal device,
The erasure means erases the content stored in the received content storage means after the lapse of the survival time changed by the survival time change means;
An information terminal device.

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